I agree with your procedure, but would like to add a few things. Some
Hondas have a system where the ECU can change the set voltage for the
voltage regulator. Under certain circumstances (warm engine, low
electrical load etc.) the ECU will call for lower voltage at idle. This
can be defeated by stepping on the brake. So to avoid erroneous
readings, step on the brake while doing the voltage measurements. I
don't know when Honda started using this system, but I know my '94 has
it.

Also, I doubt 13.7 is the right value. The spec. for the '87 Civic and
also the '94 Civic is 14.5 V +/- 0.6 V measured at the battery with no
electrical accessories turned on (pr. Helms service manual).


Charlie S wrote:
>
> When your lights go bright and the fan speeds up etc. that means the
> voltage has gone up above normal.
> First thing I would do is check the voltage. Put a voltmeter on the
> battery terminals. A fully charged battery should show 12.7 volts. Now
> turn the engine on and read the voltage on the battery terminals. It
> should now read about 13.7 volts. Have someone change the speed on the
> engine and watch the voltmeter....if the alternator is good it should
> not change voltage.
> Alternators produce an alternating current(AC), have a rectifer
> circuit in them to produce a DC current and a built-in regulator to
> give a 13.7 volt DC output.
> I am going to guess you have a bad alternator.
>
> Find a mechanic that understands electrical, not all mechanics
> understand electrical problems.
>
> I looked a 1990 "Accord" wiring diagram and it shows two wires from
> the alternator to the "engine control module'. I have no idea what
> that is for.
>
> Cheers, Charlie
>
> On 26 Dec 2003 16:13:33 -0800, xbiggwbx@aol.com (Wayne) wrote:
>
> >Hello!
> >I own a 1990 Honda Civic, 4-door/4 cylinder car. When driving, I
> >noticed that my headlights and dash board lights get very bright, and
> >then dims back to normal. At the same time this happens, my defroster
> >fan motor, speeds up and then slows down to normal in conjuction with
> >the headlight and dashboard lights.
> >
> >I also notice that my battery light on my dash board flickers on and
> >off occasionally apart form the dash board lights.
> >
> >
> >Oh by the way,
> >
> >My alternator was replaced March of 2003. Prior to changing my
> >alternator, my battery light constantly stayed on.
> >
> >My mechanic recently checked my fan belt and told me that it was o.k.
> >
> >Does anyone have a solution to what this problem might be?
> >
> >
> >Please email me: xbiggwbx@aol.com

 

I agree with your procedure, but would like to add a few things. Some
Hondas have a system where the ECU can change the set voltage for the
voltage regulator. Under certain circumstances (warm engine, low
electrical load etc.) the ECU will call for lower voltage at idle. This
can be defeated by stepping on the brake. So to avoid erroneous
readings, step on the brake while doing the voltage measurements. I
don't know when Honda started using this system, but I know my '94 has
it.

Also, I doubt 13.7 is the right value. The spec. for the '87 Civic and
also the '94 Civic is 14.5 V +/- 0.6 V measured at the battery with no
electrical accessories turned on (pr. Helms service manual).


Charlie S wrote:
>
> When your lights go bright and the fan speeds up etc. that means the
> voltage has gone up above normal.
> First thing I would do is check the voltage. Put a voltmeter on the
> battery terminals. A fully charged battery should show 12.7 volts. Now
> turn the engine on and read the voltage on the battery terminals. It
> should now read about 13.7 volts. Have someone change the speed on the
> engine and watch the voltmeter....if the alternator is good it should
> not change voltage.
> Alternators produce an alternating current(AC), have a rectifer
> circuit in them to produce a DC current and a built-in regulator to
> give a 13.7 volt DC output.
> I am going to guess you have a bad alternator.
>
> Find a mechanic that understands electrical, not all mechanics
> understand electrical problems.
>
> I looked a 1990 "Accord" wiring diagram and it shows two wires from
> the alternator to the "engine control module'. I have no idea what
> that is for.
>
> Cheers, Charlie
>
> On 26 Dec 2003 16:13:33 -0800, xbiggwbx@aol.com (Wayne) wrote:
>
> >Hello!
> >I own a 1990 Honda Civic, 4-door/4 cylinder car. When driving, I
> >noticed that my headlights and dash board lights get very bright, and
> >then dims back to normal. At the same time this happens, my defroster
> >fan motor, speeds up and then slows down to normal in conjuction with
> >the headlight and dashboard lights.
> >
> >I also notice that my battery light on my dash board flickers on and
> >off occasionally apart form the dash board lights.
> >
> >
> >Oh by the way,
> >
> >My alternator was replaced March of 2003. Prior to changing my
> >alternator, my battery light constantly stayed on.
> >
> >My mechanic recently checked my fan belt and told me that it was o.k.
> >
> >Does anyone have a solution to what this problem might be?
> >
> >
> >Please email me: xbiggwbx@aol.com

 

Thank you Randolph, I was guessing the alternator output voltage.

If the ECU is buggered it sounds like money??

The only time I would think they may want to boost the voltage is to
compensate for the starter pulling the voltage down.

I wish you luck, Charlie

On Fri, 16 Jan 2004 06:24:48 GMT, Randolph <trash@junkmail.com> wrote:

>I agree with your procedure, but would like to add a few things. Some
>Hondas have a system where the ECU can change the set voltage for the
>voltage regulator. Under certain circumstances (warm engine, low
>electrical load etc.) the ECU will call for lower voltage at idle. This
>can be defeated by stepping on the brake. So to avoid erroneous
>readings, step on the brake while doing the voltage measurements. I
>don't know when Honda started using this system, but I know my '94 has
>it.
>
>Also, I doubt 13.7 is the right value. The spec. for the '87 Civic and
>also the '94 Civic is 14.5 V +/- 0.6 V measured at the battery with no
>electrical accessories turned on (pr. Helms service manual).
>
>
>Charlie S wrote:
>>
>> When your lights go bright and the fan speeds up etc. that means the
>> voltage has gone up above normal.
>> First thing I would do is check the voltage. Put a voltmeter on the
>> battery terminals. A fully charged battery should show 12.7 volts. Now
>> turn the engine on and read the voltage on the battery terminals. It
>> should now read about 13.7 volts. Have someone change the speed on the
>> engine and watch the voltmeter....if the alternator is good it should
>> not change voltage.
>> Alternators produce an alternating current(AC), have a rectifer
>> circuit in them to produce a DC current and a built-in regulator to
>> give a 13.7 volt DC output.
>> I am going to guess you have a bad alternator.
>>
>> Find a mechanic that understands electrical, not all mechanics
>> understand electrical problems.
>>
>> I looked a 1990 "Accord" wiring diagram and it shows two wires from
>> the alternator to the "engine control module'. I have no idea what
>> that is for.
>>
>> Cheers, Charlie
>>
>> On 26 Dec 2003 16:13:33 -0800, xbiggwbx@aol.com (Wayne) wrote:
>>
>> >Hello!
>> >I own a 1990 Honda Civic, 4-door/4 cylinder car. When driving, I
>> >noticed that my headlights and dash board lights get very bright, and
>> >then dims back to normal. At the same time this happens, my defroster
>> >fan motor, speeds up and then slows down to normal in conjuction with
>> >the headlight and dashboard lights.
>> >
>> >I also notice that my battery light on my dash board flickers on and
>> >off occasionally apart form the dash board lights.
>> >
>> >
>> >Oh by the way,
>> >
>> >My alternator was replaced March of 2003. Prior to changing my
>> >alternator, my battery light constantly stayed on.
>> >
>> >My mechanic recently checked my fan belt and told me that it was o.k.
>> >
>> >Does anyone have a solution to what this problem might be?
>> >
>> >
>> >Please email me: xbiggwbx@aol.com

 

Thank you Randolph, I was guessing the alternator output voltage.

If the ECU is buggered it sounds like money??

The only time I would think they may want to boost the voltage is to
compensate for the starter pulling the voltage down.

I wish you luck, Charlie

On Fri, 16 Jan 2004 06:24:48 GMT, Randolph <trash@junkmail.com> wrote:

>I agree with your procedure, but would like to add a few things. Some
>Hondas have a system where the ECU can change the set voltage for the
>voltage regulator. Under certain circumstances (warm engine, low
>electrical load etc.) the ECU will call for lower voltage at idle. This
>can be defeated by stepping on the brake. So to avoid erroneous
>readings, step on the brake while doing the voltage measurements. I
>don't know when Honda started using this system, but I know my '94 has
>it.
>
>Also, I doubt 13.7 is the right value. The spec. for the '87 Civic and
>also the '94 Civic is 14.5 V +/- 0.6 V measured at the battery with no
>electrical accessories turned on (pr. Helms service manual).
>
>
>Charlie S wrote:
>>
>> When your lights go bright and the fan speeds up etc. that means the
>> voltage has gone up above normal.
>> First thing I would do is check the voltage. Put a voltmeter on the
>> battery terminals. A fully charged battery should show 12.7 volts. Now
>> turn the engine on and read the voltage on the battery terminals. It
>> should now read about 13.7 volts. Have someone change the speed on the
>> engine and watch the voltmeter....if the alternator is good it should
>> not change voltage.
>> Alternators produce an alternating current(AC), have a rectifer
>> circuit in them to produce a DC current and a built-in regulator to
>> give a 13.7 volt DC output.
>> I am going to guess you have a bad alternator.
>>
>> Find a mechanic that understands electrical, not all mechanics
>> understand electrical problems.
>>
>> I looked a 1990 "Accord" wiring diagram and it shows two wires from
>> the alternator to the "engine control module'. I have no idea what
>> that is for.
>>
>> Cheers, Charlie
>>
>> On 26 Dec 2003 16:13:33 -0800, xbiggwbx@aol.com (Wayne) wrote:
>>
>> >Hello!
>> >I own a 1990 Honda Civic, 4-door/4 cylinder car. When driving, I
>> >noticed that my headlights and dash board lights get very bright, and
>> >then dims back to normal. At the same time this happens, my defroster
>> >fan motor, speeds up and then slows down to normal in conjuction with
>> >the headlight and dashboard lights.
>> >
>> >I also notice that my battery light on my dash board flickers on and
>> >off occasionally apart form the dash board lights.
>> >
>> >
>> >Oh by the way,
>> >
>> >My alternator was replaced March of 2003. Prior to changing my
>> >alternator, my battery light constantly stayed on.
>> >
>> >My mechanic recently checked my fan belt and told me that it was o.k.
>> >
>> >Does anyone have a solution to what this problem might be?
>> >
>> >
>> >Please email me: xbiggwbx@aol.com

 

Thank you Randolph, I was guessing the alternator output voltage.

If the ECU is buggered it sounds like money??

The only time I would think they may want to boost the voltage is to
compensate for the starter pulling the voltage down.

I wish you luck, Charlie

On Fri, 16 Jan 2004 06:24:48 GMT, Randolph <trash@junkmail.com> wrote:

>I agree with your procedure, but would like to add a few things. Some
>Hondas have a system where the ECU can change the set voltage for the
>voltage regulator. Under certain circumstances (warm engine, low
>electrical load etc.) the ECU will call for lower voltage at idle. This
>can be defeated by stepping on the brake. So to avoid erroneous
>readings, step on the brake while doing the voltage measurements. I
>don't know when Honda started using this system, but I know my '94 has
>it.
>
>Also, I doubt 13.7 is the right value. The spec. for the '87 Civic and
>also the '94 Civic is 14.5 V +/- 0.6 V measured at the battery with no
>electrical accessories turned on (pr. Helms service manual).
>
>
>Charlie S wrote:
>>
>> When your lights go bright and the fan speeds up etc. that means the
>> voltage has gone up above normal.
>> First thing I would do is check the voltage. Put a voltmeter on the
>> battery terminals. A fully charged battery should show 12.7 volts. Now
>> turn the engine on and read the voltage on the battery terminals. It
>> should now read about 13.7 volts. Have someone change the speed on the
>> engine and watch the voltmeter....if the alternator is good it should
>> not change voltage.
>> Alternators produce an alternating current(AC), have a rectifer
>> circuit in them to produce a DC current and a built-in regulator to
>> give a 13.7 volt DC output.
>> I am going to guess you have a bad alternator.
>>
>> Find a mechanic that understands electrical, not all mechanics
>> understand electrical problems.
>>
>> I looked a 1990 "Accord" wiring diagram and it shows two wires from
>> the alternator to the "engine control module'. I have no idea what
>> that is for.
>>
>> Cheers, Charlie
>>
>> On 26 Dec 2003 16:13:33 -0800, xbiggwbx@aol.com (Wayne) wrote:
>>
>> >Hello!
>> >I own a 1990 Honda Civic, 4-door/4 cylinder car. When driving, I
>> >noticed that my headlights and dash board lights get very bright, and
>> >then dims back to normal. At the same time this happens, my defroster
>> >fan motor, speeds up and then slows down to normal in conjuction with
>> >the headlight and dashboard lights.
>> >
>> >I also notice that my battery light on my dash board flickers on and
>> >off occasionally apart form the dash board lights.
>> >
>> >
>> >Oh by the way,
>> >
>> >My alternator was replaced March of 2003. Prior to changing my
>> >alternator, my battery light constantly stayed on.
>> >
>> >My mechanic recently checked my fan belt and told me that it was o.k.
>> >
>> >Does anyone have a solution to what this problem might be?
>> >
>> >
>> >Please email me: xbiggwbx@aol.com

 

Thank you Randolph, I was guessing the alternator output voltage.

If the ECU is buggered it sounds like money??

The only time I would think they may want to boost the voltage is to
compensate for the starter pulling the voltage down.

I wish you luck, Charlie

On Fri, 16 Jan 2004 06:24:48 GMT, Randolph <trash@junkmail.com> wrote:

>I agree with your procedure, but would like to add a few things. Some
>Hondas have a system where the ECU can change the set voltage for the
>voltage regulator. Under certain circumstances (warm engine, low
>electrical load etc.) the ECU will call for lower voltage at idle. This
>can be defeated by stepping on the brake. So to avoid erroneous
>readings, step on the brake while doing the voltage measurements. I
>don't know when Honda started using this system, but I know my '94 has
>it.
>
>Also, I doubt 13.7 is the right value. The spec. for the '87 Civic and
>also the '94 Civic is 14.5 V +/- 0.6 V measured at the battery with no
>electrical accessories turned on (pr. Helms service manual).
>
>
>Charlie S wrote:
>>
>> When your lights go bright and the fan speeds up etc. that means the
>> voltage has gone up above normal.
>> First thing I would do is check the voltage. Put a voltmeter on the
>> battery terminals. A fully charged battery should show 12.7 volts. Now
>> turn the engine on and read the voltage on the battery terminals. It
>> should now read about 13.7 volts. Have someone change the speed on the
>> engine and watch the voltmeter....if the alternator is good it should
>> not change voltage.
>> Alternators produce an alternating current(AC), have a rectifer
>> circuit in them to produce a DC current and a built-in regulator to
>> give a 13.7 volt DC output.
>> I am going to guess you have a bad alternator.
>>
>> Find a mechanic that understands electrical, not all mechanics
>> understand electrical problems.
>>
>> I looked a 1990 "Accord" wiring diagram and it shows two wires from
>> the alternator to the "engine control module'. I have no idea what
>> that is for.
>>
>> Cheers, Charlie
>>
>> On 26 Dec 2003 16:13:33 -0800, xbiggwbx@aol.com (Wayne) wrote:
>>
>> >Hello!
>> >I own a 1990 Honda Civic, 4-door/4 cylinder car. When driving, I
>> >noticed that my headlights and dash board lights get very bright, and
>> >then dims back to normal. At the same time this happens, my defroster
>> >fan motor, speeds up and then slows down to normal in conjuction with
>> >the headlight and dashboard lights.
>> >
>> >I also notice that my battery light on my dash board flickers on and
>> >off occasionally apart form the dash board lights.
>> >
>> >
>> >Oh by the way,
>> >
>> >My alternator was replaced March of 2003. Prior to changing my
>> >alternator, my battery light constantly stayed on.
>> >
>> >My mechanic recently checked my fan belt and told me that it was o.k.
>> >
>> >Does anyone have a solution to what this problem might be?
>> >
>> >
>> >Please email me: xbiggwbx@aol.com

 

The nominal voltage is 14.5 V +/- 0.6V. It is never "boosted" to a
higher voltage. Rather it is reduced under some circumstance in order to
increase fuel economy. On my '94 Civic there are two separate set of
conditions that will cause the alternator output voltage to be reduced:

1. While running the starter. Lowering the set point for the voltage
regulator makes the engine easier to crank (it does not decrease battery
voltage). Increasing it to provide more power to the starter would not
work unless you have perfected perpetual motion.

2. If all the following are met: Electrical load less than 10 A, vehicle
speed less than 40 mph, engine speed below 3600 RPM, engine coolant
temperature higher than 140 °F, A/C turned off, intake air temperature
above 65 °F, brakes not applied, fuel cut-off not in effect.

While it is possible that a fried ECU could either never call for
reduced voltage or worse, always call for reduced voltage, it is very
rare that the ECU is the cause of charging system problems.



Charlie S wrote:
>
> Thank you Randolph, I was guessing the alternator output voltage.
>
> If the ECU is buggered it sounds like money??
>
> The only time I would think they may want to boost the voltage is to
> compensate for the starter pulling the voltage down.
>
> I wish you luck, Charlie
>
> On Fri, 16 Jan 2004 06:24:48 GMT, Randolph <trash@junkmail.com> wrote:
>
> >I agree with your procedure, but would like to add a few things. Some
> >Hondas have a system where the ECU can change the set voltage for the
> >voltage regulator. Under certain circumstances (warm engine, low
> >electrical load etc.) the ECU will call for lower voltage at idle. This
> >can be defeated by stepping on the brake. So to avoid erroneous
> >readings, step on the brake while doing the voltage measurements. I
> >don't know when Honda started using this system, but I know my '94 has
> >it.
> >
> >Also, I doubt 13.7 is the right value. The spec. for the '87 Civic and
> >also the '94 Civic is 14.5 V +/- 0.6 V measured at the battery with no
> >electrical accessories turned on (pr. Helms service manual).
> >
> >
> >Charlie S wrote:
> >>
> >> When your lights go bright and the fan speeds up etc. that means the
> >> voltage has gone up above normal.
> >> First thing I would do is check the voltage. Put a voltmeter on the
> >> battery terminals. A fully charged battery should show 12.7 volts. Now
> >> turn the engine on and read the voltage on the battery terminals. It
> >> should now read about 13.7 volts. Have someone change the speed on the
> >> engine and watch the voltmeter....if the alternator is good it should
> >> not change voltage.
> >> Alternators produce an alternating current(AC), have a rectifer
> >> circuit in them to produce a DC current and a built-in regulator to
> >> give a 13.7 volt DC output.
> >> I am going to guess you have a bad alternator.
> >>
> >> Find a mechanic that understands electrical, not all mechanics
> >> understand electrical problems.
> >>
> >> I looked a 1990 "Accord" wiring diagram and it shows two wires from
> >> the alternator to the "engine control module'. I have no idea what
> >> that is for.
> >>
> >> Cheers, Charlie
> >>
> >> On 26 Dec 2003 16:13:33 -0800, xbiggwbx@aol.com (Wayne) wrote:
> >>
> >> >Hello!
> >> >I own a 1990 Honda Civic, 4-door/4 cylinder car. When driving, I
> >> >noticed that my headlights and dash board lights get very bright, and
> >> >then dims back to normal. At the same time this happens, my defroster
> >> >fan motor, speeds up and then slows down to normal in conjuction with
> >> >the headlight and dashboard lights.
> >> >
> >> >I also notice that my battery light on my dash board flickers on and
> >> >off occasionally apart form the dash board lights.
> >> >
> >> >
> >> >Oh by the way,
> >> >
> >> >My alternator was replaced March of 2003. Prior to changing my
> >> >alternator, my battery light constantly stayed on.
> >> >
> >> >My mechanic recently checked my fan belt and told me that it was o.k.
> >> >
> >> >Does anyone have a solution to what this problem might be?
> >> >
> >> >
> >> >Please email me: xbiggwbx@aol.com

 

The nominal voltage is 14.5 V +/- 0.6V. It is never "boosted" to a
higher voltage. Rather it is reduced under some circumstance in order to
increase fuel economy. On my '94 Civic there are two separate set of
conditions that will cause the alternator output voltage to be reduced:

1. While running the starter. Lowering the set point for the voltage
regulator makes the engine easier to crank (it does not decrease battery
voltage). Increasing it to provide more power to the starter would not
work unless you have perfected perpetual motion.

2. If all the following are met: Electrical load less than 10 A, vehicle
speed less than 40 mph, engine speed below 3600 RPM, engine coolant
temperature higher than 140 °F, A/C turned off, intake air temperature
above 65 °F, brakes not applied, fuel cut-off not in effect.

While it is possible that a fried ECU could either never call for
reduced voltage or worse, always call for reduced voltage, it is very
rare that the ECU is the cause of charging system problems.



Charlie S wrote:
>
> Thank you Randolph, I was guessing the alternator output voltage.
>
> If the ECU is buggered it sounds like money??
>
> The only time I would think they may want to boost the voltage is to
> compensate for the starter pulling the voltage down.
>
> I wish you luck, Charlie
>
> On Fri, 16 Jan 2004 06:24:48 GMT, Randolph <trash@junkmail.com> wrote:
>
> >I agree with your procedure, but would like to add a few things. Some
> >Hondas have a system where the ECU can change the set voltage for the
> >voltage regulator. Under certain circumstances (warm engine, low
> >electrical load etc.) the ECU will call for lower voltage at idle. This
> >can be defeated by stepping on the brake. So to avoid erroneous
> >readings, step on the brake while doing the voltage measurements. I
> >don't know when Honda started using this system, but I know my '94 has
> >it.
> >
> >Also, I doubt 13.7 is the right value. The spec. for the '87 Civic and
> >also the '94 Civic is 14.5 V +/- 0.6 V measured at the battery with no
> >electrical accessories turned on (pr. Helms service manual).
> >
> >
> >Charlie S wrote:
> >>
> >> When your lights go bright and the fan speeds up etc. that means the
> >> voltage has gone up above normal.
> >> First thing I would do is check the voltage. Put a voltmeter on the
> >> battery terminals. A fully charged battery should show 12.7 volts. Now
> >> turn the engine on and read the voltage on the battery terminals. It
> >> should now read about 13.7 volts. Have someone change the speed on the
> >> engine and watch the voltmeter....if the alternator is good it should
> >> not change voltage.
> >> Alternators produce an alternating current(AC), have a rectifer
> >> circuit in them to produce a DC current and a built-in regulator to
> >> give a 13.7 volt DC output.
> >> I am going to guess you have a bad alternator.
> >>
> >> Find a mechanic that understands electrical, not all mechanics
> >> understand electrical problems.
> >>
> >> I looked a 1990 "Accord" wiring diagram and it shows two wires from
> >> the alternator to the "engine control module'. I have no idea what
> >> that is for.
> >>
> >> Cheers, Charlie
> >>
> >> On 26 Dec 2003 16:13:33 -0800, xbiggwbx@aol.com (Wayne) wrote:
> >>
> >> >Hello!
> >> >I own a 1990 Honda Civic, 4-door/4 cylinder car. When driving, I
> >> >noticed that my headlights and dash board lights get very bright, and
> >> >then dims back to normal. At the same time this happens, my defroster
> >> >fan motor, speeds up and then slows down to normal in conjuction with
> >> >the headlight and dashboard lights.
> >> >
> >> >I also notice that my battery light on my dash board flickers on and
> >> >off occasionally apart form the dash board lights.
> >> >
> >> >
> >> >Oh by the way,
> >> >
> >> >My alternator was replaced March of 2003. Prior to changing my
> >> >alternator, my battery light constantly stayed on.
> >> >
> >> >My mechanic recently checked my fan belt and told me that it was o.k.
> >> >
> >> >Does anyone have a solution to what this problem might be?
> >> >
> >> >
> >> >Please email me: xbiggwbx@aol.com

 

The nominal voltage is 14.5 V +/- 0.6V. It is never "boosted" to a
higher voltage. Rather it is reduced under some circumstance in order to
increase fuel economy. On my '94 Civic there are two separate set of
conditions that will cause the alternator output voltage to be reduced:

1. While running the starter. Lowering the set point for the voltage
regulator makes the engine easier to crank (it does not decrease battery
voltage). Increasing it to provide more power to the starter would not
work unless you have perfected perpetual motion.

2. If all the following are met: Electrical load less than 10 A, vehicle
speed less than 40 mph, engine speed below 3600 RPM, engine coolant
temperature higher than 140 °F, A/C turned off, intake air temperature
above 65 °F, brakes not applied, fuel cut-off not in effect.

While it is possible that a fried ECU could either never call for
reduced voltage or worse, always call for reduced voltage, it is very
rare that the ECU is the cause of charging system problems.



Charlie S wrote:
>
> Thank you Randolph, I was guessing the alternator output voltage.
>
> If the ECU is buggered it sounds like money??
>
> The only time I would think they may want to boost the voltage is to
> compensate for the starter pulling the voltage down.
>
> I wish you luck, Charlie
>
> On Fri, 16 Jan 2004 06:24:48 GMT, Randolph <trash@junkmail.com> wrote:
>
> >I agree with your procedure, but would like to add a few things. Some
> >Hondas have a system where the ECU can change the set voltage for the
> >voltage regulator. Under certain circumstances (warm engine, low
> >electrical load etc.) the ECU will call for lower voltage at idle. This
> >can be defeated by stepping on the brake. So to avoid erroneous
> >readings, step on the brake while doing the voltage measurements. I
> >don't know when Honda started using this system, but I know my '94 has
> >it.
> >
> >Also, I doubt 13.7 is the right value. The spec. for the '87 Civic and
> >also the '94 Civic is 14.5 V +/- 0.6 V measured at the battery with no
> >electrical accessories turned on (pr. Helms service manual).
> >
> >
> >Charlie S wrote:
> >>
> >> When your lights go bright and the fan speeds up etc. that means the
> >> voltage has gone up above normal.
> >> First thing I would do is check the voltage. Put a voltmeter on the
> >> battery terminals. A fully charged battery should show 12.7 volts. Now
> >> turn the engine on and read the voltage on the battery terminals. It
> >> should now read about 13.7 volts. Have someone change the speed on the
> >> engine and watch the voltmeter....if the alternator is good it should
> >> not change voltage.
> >> Alternators produce an alternating current(AC), have a rectifer
> >> circuit in them to produce a DC current and a built-in regulator to
> >> give a 13.7 volt DC output.
> >> I am going to guess you have a bad alternator.
> >>
> >> Find a mechanic that understands electrical, not all mechanics
> >> understand electrical problems.
> >>
> >> I looked a 1990 "Accord" wiring diagram and it shows two wires from
> >> the alternator to the "engine control module'. I have no idea what
> >> that is for.
> >>
> >> Cheers, Charlie
> >>
> >> On 26 Dec 2003 16:13:33 -0800, xbiggwbx@aol.com (Wayne) wrote:
> >>
> >> >Hello!
> >> >I own a 1990 Honda Civic, 4-door/4 cylinder car. When driving, I
> >> >noticed that my headlights and dash board lights get very bright, and
> >> >then dims back to normal. At the same time this happens, my defroster
> >> >fan motor, speeds up and then slows down to normal in conjuction with
> >> >the headlight and dashboard lights.
> >> >
> >> >I also notice that my battery light on my dash board flickers on and
> >> >off occasionally apart form the dash board lights.
> >> >
> >> >
> >> >Oh by the way,
> >> >
> >> >My alternator was replaced March of 2003. Prior to changing my
> >> >alternator, my battery light constantly stayed on.
> >> >
> >> >My mechanic recently checked my fan belt and told me that it was o.k.
> >> >
> >> >Does anyone have a solution to what this problem might be?
> >> >
> >> >
> >> >Please email me: xbiggwbx@aol.com

 

The nominal voltage is 14.5 V +/- 0.6V. It is never "boosted" to a
higher voltage. Rather it is reduced under some circumstance in order to
increase fuel economy. On my '94 Civic there are two separate set of
conditions that will cause the alternator output voltage to be reduced:

1. While running the starter. Lowering the set point for the voltage
regulator makes the engine easier to crank (it does not decrease battery
voltage). Increasing it to provide more power to the starter would not
work unless you have perfected perpetual motion.

2. If all the following are met: Electrical load less than 10 A, vehicle
speed less than 40 mph, engine speed below 3600 RPM, engine coolant
temperature higher than 140 °F, A/C turned off, intake air temperature
above 65 °F, brakes not applied, fuel cut-off not in effect.

While it is possible that a fried ECU could either never call for
reduced voltage or worse, always call for reduced voltage, it is very
rare that the ECU is the cause of charging system problems.



Charlie S wrote:
>
> Thank you Randolph, I was guessing the alternator output voltage.
>
> If the ECU is buggered it sounds like money??
>
> The only time I would think they may want to boost the voltage is to
> compensate for the starter pulling the voltage down.
>
> I wish you luck, Charlie
>
> On Fri, 16 Jan 2004 06:24:48 GMT, Randolph <trash@junkmail.com> wrote:
>
> >I agree with your procedure, but would like to add a few things. Some
> >Hondas have a system where the ECU can change the set voltage for the
> >voltage regulator. Under certain circumstances (warm engine, low
> >electrical load etc.) the ECU will call for lower voltage at idle. This
> >can be defeated by stepping on the brake. So to avoid erroneous
> >readings, step on the brake while doing the voltage measurements. I
> >don't know when Honda started using this system, but I know my '94 has
> >it.
> >
> >Also, I doubt 13.7 is the right value. The spec. for the '87 Civic and
> >also the '94 Civic is 14.5 V +/- 0.6 V measured at the battery with no
> >electrical accessories turned on (pr. Helms service manual).
> >
> >
> >Charlie S wrote:
> >>
> >> When your lights go bright and the fan speeds up etc. that means the
> >> voltage has gone up above normal.
> >> First thing I would do is check the voltage. Put a voltmeter on the
> >> battery terminals. A fully charged battery should show 12.7 volts. Now
> >> turn the engine on and read the voltage on the battery terminals. It
> >> should now read about 13.7 volts. Have someone change the speed on the
> >> engine and watch the voltmeter....if the alternator is good it should
> >> not change voltage.
> >> Alternators produce an alternating current(AC), have a rectifer
> >> circuit in them to produce a DC current and a built-in regulator to
> >> give a 13.7 volt DC output.
> >> I am going to guess you have a bad alternator.
> >>
> >> Find a mechanic that understands electrical, not all mechanics
> >> understand electrical problems.
> >>
> >> I looked a 1990 "Accord" wiring diagram and it shows two wires from
> >> the alternator to the "engine control module'. I have no idea what
> >> that is for.
> >>
> >> Cheers, Charlie
> >>
> >> On 26 Dec 2003 16:13:33 -0800, xbiggwbx@aol.com (Wayne) wrote:
> >>
> >> >Hello!
> >> >I own a 1990 Honda Civic, 4-door/4 cylinder car. When driving, I
> >> >noticed that my headlights and dash board lights get very bright, and
> >> >then dims back to normal. At the same time this happens, my defroster
> >> >fan motor, speeds up and then slows down to normal in conjuction with
> >> >the headlight and dashboard lights.
> >> >
> >> >I also notice that my battery light on my dash board flickers on and
> >> >off occasionally apart form the dash board lights.
> >> >
> >> >
> >> >Oh by the way,
> >> >
> >> >My alternator was replaced March of 2003. Prior to changing my
> >> >alternator, my battery light constantly stayed on.
> >> >
> >> >My mechanic recently checked my fan belt and told me that it was o.k.
> >> >
> >> >Does anyone have a solution to what this problem might be?
> >> >
> >> >
> >> >Please email me: xbiggwbx@aol.com