Can anyone answer a question I have about the ABS system....

[97moneypit]

I have a '97 with 52k miles I picked up about a month ago. It's still a moneypit but I love it.

Anyway, there is a little electrical abnormality that I would like to figure out. I was hoping that another CAC member might be able to give me some insight into this glitch.

I am not absolutely positive about the time factor, but I think this quirk occurs about 20 to 30 minutes or so after starting the car.

There is a substantial dimming of the lights, I'd say about a 20% decrease in the intensity, when I have my foot on the brake pedal. The dimming comes in very regular intervals as if some electrical device such as a motor or a switch of some kind is drawing power from the battery by switching on for 1 sec then off for about 5 secs. It's a very regular impulse.

I was looking through the service manuals trying to get some idea of the ABS/TCS components. But of course this will take a long time to decipher.

I was just wondering if the electrical load dimming all the lights might be the result of a misbehaving component of the ABS/TCS system.

If not from that, what other devices are activated when the brakes are applied?

Thanks for any input at all.......

 

[COEX-PILOT]

I noticed that on my 2001 the light dim when I hit the window switch to up position when the windows are already up.

I have seen this before on other cars and it usually means that the batter is not fully charged. My battery volts show 14 and drop to 13.7 after driving so I would think the battery is OK.

c4c5, can you shead some 'light' on this??

 

[97moneypit]

Maybe a new batttery would be the least expensive place to start?

 

[Karl Snedeger]

My 98 Coupe did it and my 2000 FRC does it. I don't thin k about it. We drive cars that use power for just about everything and there is going to fluctuations evry now and then. When my car won't start or when error codes start showing up then I will worry about it.

 

[97moneypit]

I am not too worried about the dimming problem. I just have this sometimes irrational curiosity to know why and how things work. There is some component pulling a large load on the electrical system and I just gotta know what it is.


:bang

 

[jorge33265]

Doest sound like an issue with the battery. Check the volts on the battery using a guage. I had some issues with my 97 also.. Yes they are money pits.. Your best bet is to get an extended warranty. Yup they do write for older cars. I just got one for mine and its a 97 with 68000 miles. I was able to find one that covers 3 year 36,000 miles even covers electrical stuff like radio and AC stuff like that. It was about 1700- 1800 dollars. I still think its worth it though a good tranny repair will cost close that. If your interested I'll send you the web link..

 

[Oldvetter]

Most C5's do this, my 98 does it mainly while idling. I think C5's have poor voltage regulators, they may even use the computer as a voltage regulator.

A friend of mine "blinks" so bad while he is driving it that people pull over to the side of the road ahead of him !

By the way I have a new, good battery.

 

[97moneypit]

jorge33265

Please send me the link. I will check into the extended warranty. Thanks

Oldvetter,

Based on your NFO, a new battery would do no good. I'll just call it a GM "feature" and leave it at that.

Kirk

 

[c4c5specialist]

HI there,
A few facts concerning the c5 electrical system are in order here.
First, the Valeo A14V is a 110 amp alternator, which is digitally processed. The actual turn on signal for the digital voltage regulator is supplied by the PCM.
In another post, I have stated that the PCM actually controls the PCM, and it is by this signal, that is supplied at Terminal L.
However, being a digital voltage regulator is substantially different from the older normal analog regulators of the past. IT will take 1 sec, for the digital process to upgrade the alternator output, so that the voltage is correct at around 14 volts.
Now, also, there is a calibration that is needed from time to time, on the IPC, so that is also a consideration, in the actual voltage readout that is show to the driver.
A quick dimming, is classified normal, based on operation of the electrical system, that I have shown above.
The up side, is that the digital voltage regulators are 100 times more reliable than the older analog.
This is why sometimes, if the vehicle sits for a week or 2, you may see a 'charging system fault' for a second on first start up. This is because Terminal F sees a low voltage condition, and the PCM notes this as a charging system issue, and sends the message.
Allthebest, c4c5

 

[97moneypit]

Thanks for the NFO. After the first of the year I will take it in for some diagnostic tests.

Kirk