Dimmer fix when replacement doesn't fix?
 

Ok, so I had some dimmer issues on my '89, and replaced my dimmer module and switch...but it has the exact same symptoms. When I turn on my headlights, the dash bulbs illuminate everything properly for a few seconds, and then go out....it doesn't matter if it's in the variable position or in the locked 'brightest' position, it just flickers and goes out for good. Sometimes I'm lucky and it'll stay on a little while, but sooner or later on the drive, it will go out and never come back. If I turn the lights off and back on, it may go through the same cycle again and stay on for a few more seconds, but will go right back out.


Is there anything else I should take a look at? A particular ground, or is there some sort of logic to this dimmer module that I'm not aware of (is it checking some other part of the system that would cause it to go out?


Any help is appreciated...thanks!


Pete

Pete,

I'm assuming you have the digital gauge display?

Yes, it has the digital gauge display

Pete,

I venture to guess you have solder points that have corroded/cracked on the backside of the cluster. Search the archived, there should be plenty of how-to's to guide you. I had to repair (re-solder) mine a few years back and it has not occurred since. Most of the poor solder joints will be obvious.

Thanks - I'll check it out... right now everything else seems fine on my cluster, that's why I didn't want to go too crazy resoldering things on that cluster unless I needed to..:)


Pete

Just a quick follow-up... I *believe* I have the issue solved now. Again, I was having an issue with the interior dash lights coming on when I turned on my headlights (like normal), but a few seconds after turning them on, they would flicker quickly 3-4 times and just go out)


I pulled the cluster and removed the left and right rear pcbs, and reflowed all the solder joints on those two boards. I didn't see any cold joints or anything that jumped out at me, but the solder around the transformer (power board) looked a little strange...like it had some white residue on all the solder joints. Anyhow, after it all went back together, things looked pretty good...but I noticed my digital gauges were still bright and not dimming with the rest of the dash lights when I used the dimmer switch. This was actually my fault...I didn't fully seat the green connector going to the instrument cluster.. and once that was seated, everything worked as intended.


So, next time around, if someone runs across the same issue...you might take a look at the green harness connector to make sure the pins are in good shape and everything's clean...whatever is tied into the dimmer switch has some wiring that goes through there. Not exactly scientific, and not something you probably couldn't pick up in the wiring diagram, but at least it's a quick place to look...


Pete

A couple weeks later, it's been a lot better, but I've noticed two occasions where that flicker came back for 2 seconds, and the dash/console instruments lights did go drak on the instrument panel, while the left side gauges all became full brightness...






Is this tied into any sort of solar/light sensor, where the console/dash illumination will exhibit this behavior if the sensor detects a certain amount of ambient light? Just wondering..because there's nothing left to reflow solder to, etc... :)


Pete

Pete,

I re-read your post from the 16th, and I would suspect there may be some residue under a solder point or two. I had to re-flow my entire board(s) and have had no problem for about six years now.

I did notice the leads from the connector terminating on the board(s) were really contaminated/corroded/residue encrusted on mine. I suspect the high humidity I live in, plus no garage to contribute greatly to needing to continuously clean connectors and grounds.

I have never seen any reference to any solar sensor the the lighting system on our MY vehicles. Only reference I've seen is affiliated to the Climate Control Unit.

With the info in this thread, I just managed to fix the dimmer lights by opening and spraying that green connector under the dashboard... Many thanks to all... :-)

Hey everyone - sorry to ressurect this old thread, but I finally fixed my original issue with the dimmer/dash lights coming on and flickering until they stayed off completely.

This would affect all the dash lights, AC lights, center console, cigarette lighter lighting, radio, everything...

What it ended up being, after testing wiring around that dimmer module, was that the dimmer switch wasn't getting the ground signal from the headlight module switch consistantly...it would have a slight voltage to it, not ground...and thus triggered the circuit to turn off the dimming module and interior lighting. On the 1989 at least, the headlight switch is this white plastic housing which actually contains two small black switches inside of it. Everything pops apart fairly easily (though be careful when opening those switches as they seem very sensitive and things WILL pop out if you're not careful). Wiggling the wires going to those two switches within the headlight switch triggered the interior lighting to flicker on and off, so I knew I finally hit the right spot.

The switches are sort of cheaply put together - they seem fairly easy to flex the metal tabs around and cause the switch to not work at all. I couldn't necessarily tell if the switches were the issue, or the wiring had flaked out - reflowing the solder didn't seem to help. Thus, I decided to replace the wiring, new solder, and verify everything was aligned properly in the two switches.

So far, so good... we'll get some more night-time miles on the car and see if it stays working or drops me into the dark abyss.

Pete