98 Voyager wierd electical problem

[dahirolla]

How many threads are titled like that...lol.

98 voyager, 220,000 miles. Last leg of trip back to Tulsa from St. Louis, and my headlights stop working. This was a few hundred miles after I replaced the blower motor relay.

Turns out that the aftermarket relay had a weak spade contact that pushed up into the windings and compromised it.

Now here's the strange part: No dash lights except for the gear indicator and the odometer. Interior lights can be activated individually, but not via the dash intensity roller switch on the left of the steering wheel. No parking lights. No headlights, except when holding the hi-beam toggle back. Let go of the hi-beam lever, and the lights go back off. Usually. But sometimes they'll stay on in the hi-beam position.

I can't think of any other weirdness, except that the first time the headlamps started acting screwy the dome lights would come on when I pulled back on the hi-beam toggle.

All fuses are good, although I had to replace the parking lights fuse (40 amp), and all relays are good.

I pulled the IOD fuse for about 30 min, and no change.

Any ideas?

[Alphabravo]

Sounds to me like all your problems are tied to the light switch. Either no power getting to it or the switch itself is bad. The headlights coming on when you pull the high-beam lever and then going off when you let go is a normal function when your headlights are off. This is so you can flash you lights to signal other drivers during the day. The high beams are only meant to stay on when your headlights are already on. I would get a schematic to see which wire is supposed to have power at the switch. How are the radio lights? Are they bright? That is another indication that your lights are just "off" leading back to a problem with the light switch.
Good luck.

[RIP]

If it's not the switch assembly the major players are the PDC and BCM. The PDC supplies the power to all the lighting and the BCM controls the grounds to the relays that control the lighting and panel lamp drivers are in the BCM. The combination flasher module and BCM have a hand in control parking and headlights.
Sometimes it takes more than pulling the IOD fuse to reset the BCM. That only removes one power source and there are several. Try disconnecting the negative battery lead for a good 20 minutes. Try tapping on the BCM and shaking wire harnesses at the BCM and PDC. The PDC is known to have corrosion problems. Check the PDC connections.

[dahirolla]

Thanks to both of you. I left the battery unplugged for a few hours tonight, reconnected, and same thing.

Funny thing is that all the light related warning chimes work. If I have the ignition switch in the off position, leaving either the interior lights switch, or the headlamps switch in the on position results in the warning chimes.

Seems like the switch working at least somewhat if it's setting off the warnings.

Any ideas? I'll yank on wires tomorrow. Going to sleep now...

[dahirolla]

So I yanked on the wires, reseated the plugs on the BCM, but haven't yanked on the PCM yet. I'll do that next. From what I can tell everything operates (interior reading lights, glove compartment light, flashers, and high-beams) when activated by pulling back on the high/low toggle, etc. but not when activated via the headlamp switch assymbly, which, as RIP mentioned, is grounded via the BCM.

How do I test the BCM ground? Is there only one wire that grounds the BCM? If I ground the lead exiting the BCM to the low or high beam relay, it'll tell me which side of the BCM the problem is on, but will I fry a relay?

And, having just personally inspected the wire harness above the BCM, I don't see how I could actually get in there to ground or test anything.

While I'm pretty sure everything is pointing to the BCM, this is my first crack at this, and I'd like to make sure I've covered everything before I go buy a BCM as a next step.

If I've proven I'm getting power to all these interior lights and the headlamps by activating them manually, it seems I'm ruling out the PDC as the problem. Would you agree?

[jpb53]

I did some searching and you have something available to you from your state's public library.
http://catalog.odl.state.ok.us/resources.html#car
This is for alldata pro. Another is the EBSCO database which has some info also. You might want to contact your local library. Libraries in our county offer alldata at all locations on their computers.

[dahirolla]

Thanks JBP. Looks like I'll have to hit the local library to have a look.

[dahirolla]

Something I neglected to mention: our stock radio has been losing power every so often. Some times it won't have power, and even the clock is off. Then after a while we'll notice the clock is back on and the radio will work. Does the radio share a ground with the headlamp and interior light switch panel?

In addition, my Haynes manual has resistance and continuity values to test both the interior lights and headlamps switches, which all check out, so I'm fairly confident I have a good switch.