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