Melted dimmer switch??

[cfassett]

Need some more help. Wondering if anyone has seen this issue before.

I've had the car about 18 months, and my '86 951 has been a bit of a project as far as getting the dash lights to work as they should. I thought I finally had this issue sorted, but then a couple weeks ago started smelling smoke about 1 mile down the road. it was coming from the dimmer switch for the dash lights. This was at around dusk, and I was able to turn off the headlights and the smoke went away almost immediately. Some quick trouble shooting told me it was the dimmer witch, on which the rear heat cover had melted and was starting to burn. I trimmed off the melted plastic and soaked the switch in vinegar, thinking there was a corrosion issue causing excessive resistance and therefore heat, but went ahead and ordered a "new to me" switch off of ebay. When this arrived, I plugged in each of the switches in turn, and turned on the lights. This was with the headlights on, but the car wasn't running. No smoke or excessive heat seen, so I plugged in the "new to me" switch and let it sit.

Well, today, I drove it for the first time with the new switch and started smelling plastic heat. Pulled the switch and it is really hot. Has anyone seen this before and has an idea what would cause this?? I sure would like dash lights, but not at the risk of a car fire.

A little background on the prior issues... The dash lights weren't working previously, until I found an issue with an incorrect ground. That was a few months ago, and seemed to sort it out until now. I had driven it with working dash lights on before this month, but not a lot. Headlight wiring has also been upgraded with the Hella kit.

Please let me know if you've seen this before and know what might cause it.

[Jfrahm]

People often put side marker W5W bulbs into the dash light sockets rather than the 3w stockers.
Gets melty! The stock bulbs work well if you re-silver the "light tunnels".

You can also switch to LED but that can make the dimming function not work well, and dimming the panel is a great way to maintain good night vision.

[cfassett]

Originally Posted by Jfrahm

People often put side marker W5W bulbs into the dash light sockets rather than the 3w stockers.
Gets melty! The stock bulbs work well if you re-silver the "light tunnels".

You can also switch to LED but that can make the dimming function not work well, and dimming the panel is a great way to maintain good night vision.

So are you saying the cause is too much power draw from the instrument bulbs? I did replace them during my previous trouble shooting process. Don’t know what wattage I used.

[cfassett]

Looks like these were the bulbs I used:

Porsche 944 Instrument Dash Bulb 12V/1.2W (Black Base) - Set of 4 NEW

[9FF]

Originally Posted by cfassett

Looks like these were the bulbs I used:

Porsche 944 Instrument Dash Bulb 12V/1.2W (Black Base) - Set of 4 NEW

Those bulbs are fine. If you’ve already checked your grounds start checking the interior lights, door and glovebox switches. Those are the likely culprits for an intermittent short which it seems is what you have.

[cfassett]

I kept messing with it this afternoon, and the issue got worse as I went. Ended up clipping the wires to the female plug so I could get it out and get a better look.

I disassembled the plug, and this is what I see:




The actual female tips are still in the housing, while the wire head came out as you see here. Are these supposed to be like this? I thought the wire connection would be all o e piece, female tip and all.

[cfassett]

Female ends out of the housing with the rest of the wires...

[Jfrahm]

I'm talking about the wedge base bulbs for the "light tunnels" not the idiot light bulbs.

Originally Posted by cfassett

Looks like these were the bulbs I used:

Porsche 944 Instrument Dash Bulb 12V/1.2W (Black Base) - Set of 4 NEW