QuestionQUESTION: My 1996 Grand Voyager has a problem with the dash lights and tail light working intermittently. I have tried to trace the wiring without success, and frankly wouldn't be to anxious to tear into a factory harness anyway. Generally, when the headlights are turned on, the dash lights and tail lights both go out. Occasionally, after a period of time, there will be an audible "click" (like some kind of relay somewhere), and the lights come back on. Likewise, occasionally they WILL work when the headlights are turned on, then after a little while, you hear a click and both dash and tail lights go off. Any thought where I could start looking for this? I can't tell from my owners manual that they share a common fuse, and even if they did, how could it only make the circuit part-time? Frustrated.
ANSWER: Hi Craig,
You may well be hearing the park lamp relay clicking which would indeed control the tail lights. It is located in the power distribution box under hood. It is the rear-most of large relays on the driver side of the box. You could try switching that one out with another one that is not crucial to see if that might be the culprit. However the fact that the dash lights go out in synchrony with the tail lights makes me think that the problem is in the main headlamp switch. That switch's position is "sensed" by the body control module which is located under the dash on the back side of the fuse box, and it activates the various circuits as required. It could be clicking too, due to a intermittent connection in the headlamp switch which sends a false signal to that module. You could try removing the headlamp switch and spraying some electrical contact cleaner inside of the body through any crack or opening in it. I agree that it is not a fuse in all likelihood because the rear and dash lights are on separate fuses.
Roland
PS Sorry for the delay, your question just appeared in the 'pool'.
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QUESTION: Well, the fix just became un-fixed again. I swapped out the relay and found no difference, I replaced the master headlamp switch and it worked for a couple of weeks (it was intermittent to begin with), but now we're right back where we started. Do you have any other suggestions?
ANSWER: Hi Craig,
In your initial question you spoke about something clicking. I wonder if you would be able to identify the source of the click: is it in the headlamp switch, the body computer/junction block under the dash at the left end, or from the engine compartment?
You say you loose the tail lights, but I would be curious to make sure that you also loose the front parking lights (if those are on when you have the headlamps on, which I think they are)?
I would also like to know if you loose the dash/tail lights when you have the headlamp switch in the park lamp position, or does this only happen when you have selected the head lamp position? So please experiment with that.
When you loose the dash lamps do you just loose the lamps which are on the cluster that are dimmable, or all dimmables such as that to heater/ac controls, radio, headlamp switch, etc.?
There are two common components in the dash/tail lamp circuitry: the head lamp switch and the body control module. Thus, either one could be the problem, as well as any common wires. There is a possibility of a loose ground wire but that wire also is needed by the head lamp switch to tell the body module to turn on the headlamps. I presume that you have not seen any loose of head lamp function, correct?
Have you noticed any relationship between the problem and rain or car washing? Or have you had any water intrusion around the corner of the windshield on the driver side?
Those are the questions which if answered might tell us what is wrong.
Roland
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QUESTION: Roland, Sorry I didn't provide complete answers the first time. There is no moisture issue, the problem pretty much occurs randomly, and there has been no past water problem on the driver side. As far as the other dimmables, when the dash lights go, ALL of the dimmables go. Only the odometer, gear indicator, and clock on the radio remain lit and bright. All others including headlamp switch, A/C controls, etc. go dark. Hope that helps!
AnswerHi Craig,
It helps to know about All the dimmables. Now how about driving around with just the park/tail lamps on and see whether you still loose anything when you just have the park/tail lamp selected on the lamp switch. It could either be the lamp switch, the body control module, or possibly a short in the head/tail circuit that is causing both them and the dimmables to go out. But first we need to try the headlamp switch in the park/tail only position to eliminate the switch and its wires as the cause. If it still fails, then I would suspect that the bcm is dropping both those signals on its own accord, if it doesn't then I suspect there is an issue with the full 'on' headlamp switch position. And how about listening carefully so you can locate what makes the clicking sound when they go off or come back on? It is a non-obvious situation as the dimmables and the tail/park lights are not connected except through both being 'driven' by the bcm.
Roland
PS:I need to ask one more question. When you reported that you switched out the parking lamp relay to no effect, can you tell me where you found that relay was located? I am working with both a '95 and a '98 manual (assuming that the '98 is virtually identical to your '96, but I just want to verify that fact).
I understand how the park lamps could go out and simultaneously the dash lamps, because the body controller depends upon the park lamp relay being activated which sends a signal for the dash lamps to be turned on by it. So it has to be either the headlamp switch, the 2 wires (park or 'on') from the head lamp switch to the relay (which may or may not go thruough the bcm, depending upon the specifics of the year model wiring diagram which I am try to infer from the location of the relay), or the relay itself is flaky (though you replaced that). So do try to see if the lamps go out by themselves when you are using the park position of your switch, and also tell me about where the relay is located. It is either in the box under the hood or in a relay 'block' in the cabin (which is why you might have heard it click).
Roland
