93 couple. My dash lights will randomly dim when I step on the brake. Also, when the lights dim the high beam indicator and service ABS lights come on. When I turn the car off they go away, and no trouble codes? :confused:

 

in my 90 the dash lights dim when i hit the brakes too. do you have a poopiety battery and an old alternator? granted, no warning lights come on for mine.


[Modified by psuvette, 10:20 PM 3/8/2004]

 

Sounds like you could have some faulty grounding and also check for belt slippage, voltage drop from alternator to battery, etc.

 

You have a poor connection to ground. Your 93 may have the same ground as my 87 for the high beam lamp which is by the steering column left side. Also in the wiring harness the ground for the high beam lamp first goes to a splice then to the ground by the steering column (87). The ground for the hi beam lamp is D1 on the connector to the cluster and is black (87).

 

So which grounds am I looking for?

 

I deffinately sounds like a bad ground, or a faulty charging system. Maybe your volts are too low, and when the brake lights come on, it is too much of a drain. Just a thought.

 

Well I know its not a faulty charging system. What ground shoudl i check

 

Good answers, all above......also check out the recent post by Agent 86.

 

Maybe you have a bad brake booster, and it's leaking the engine's vacuum away, which causes it to stumble, and the alternator puts out less volts because of it?

Is your brake pedal stiff?

 

well i'm sure thats not the case with my car...honestly my only thoughts are

1. bad battery
2. bad alt voltage regulator
3. bad ground

i'll get around to checking to checking the ground when time allows it. i had my battery and alt checked not too long ago, and supposedly they were fine.

 

i know its a ground. The alt is new, the brake booster is good,

 

The brake booster and alternator don't have a thing to do with your dash lights dimming when you brake. You have an intermittent poor quality ground from your instrument cluster to the chassis. You need to locate the ground wire from the cluster and follow it to any harness splices and then to the bolt that connects to the chassis. On my 87 the ground wire comes from pin D1 on the cluster socket and goes to a splice (where several ground wires connect together) in the wiring harness and from there a single wire that terminates in a lug under a bolt and nut on the left side of the steering column and against the firewall. Your vette probably has the same or similar wiring and you need to get under the dash and check it visually.


[Modified by jfb, 12:18 AM 3/14/2004]

 

well, that is certainly a possibility. but i tried something that leads me to believe that it is otherwise. i hooked up my multimeter to the batter terminals, and i placed it on my windshield. i started the car and it read about 14+ volts, however, as i hit the brake randomly, the voltage would drop down at the battery to 12 or so, i think.

why would a bad ground at the dash cause a systemwide drop in voltage?
:chevy

 

If your battery terminal volts drop to 12 v from 14 v with the engine running and then brake depressed, then you have trouble in your alternator circuit. With the engine off, measure the ohms between the battery positive terminal and the alternator output. It should be the same as touching the ohmeter probes together. If not, I would suspect that the fusible link in the alternator output wire is blown. With the engine running, measure the volts on the alternator output terminal and depress the brake, it should stay at about 14 volts. Also, you may have a poor cable connection to your battery. Remove the battery cables (neg first), clean the cable lugs and the battery posts and replace (neg last). Your dash lights will dim if the voltage supplied to them drops from 14 to 12 volts.
I would expect to see the battery symbol light come on too if your battery volts drop when you push on the brake with the engine running. This indicates that the alternator is not charging the battery which can happen if the fusible link is blown. The link has heat shrink on it and when blown there is carbon deposited on the inside of the heat shrink which can conduct enough current to show 14 volts on the dash voltmeter but cannot supply much current such as when you press on the brake.


[Modified by jfb, 5:38 PM 3/20/2004]

 

Hello Friends!!
I have the same problem with my 87, and I also have a funny fault, when I put on the ignition, without starting the engine, the fuelmeter seems to operate well, but when I start the engine, the meter shows a lot more in the tank, is this also a ground problem ??
Sorry that I stolen the thread,,, :seeya Regards Magnus


[Modified by Swede, 7:35 PM 3/22/2004]