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99 Diesel Ram headlight problems

Posted By: RestoRick

99 Diesel Ram headlight problems - 06/13/16 02:37 AM

Trying to get to the bottom of a recurring headlight issue.

I have a component from the engine bay lighting harness I need to replace, but I'm not sure what it is. Relay? After replacing a shorted overheated bulb this component smoked. There's one on each side of the engine bay.
I can't find it in the parts book or anywhere online.
Has a logo and the letters COMM INSTR on the case.


Posted By: SALEM1912

Re: 99 Diesel Ram headlight problems - 06/13/16 03:59 AM

Does the truck have snowplow?
Posted By: RestoRick

Re: 99 Diesel Ram headlight problems - 06/13/16 04:13 PM

No snowplow...

It has one of the suvlights.com 2 headlamp to 4 headlamp conversion harnesses on it, but these little mystery boxes are part of the factory harness as near as I can tell.

The issue with the conversion is that it turns on all the filaments on high beam and generates too much heat... hence the shorted bulb and blown fuse on the aftermarket harness. At least that's what it looks like at this point. With new bulbs and fuse, the box I'm trying to identify started to smoke and the lights still wouldn't come on.
The dead lamps are only on the right side.

Left side was stuck on high beams and dash indicator stayed on, even with ignition off.
Disconnecting the Multi-function switch & headlight switch didn't change that.. after I found the shorted bulb I was able to get the high beams on the left side working normal.

Kind of a mess.. lol

I also tried subbing the good "mystery box" from the left to the right and still can't get any lights on the right.
I have a new OEM headlight switch on the way to try.
Posted By: RestoRick

Re: 99 Diesel Ram headlight problems - 06/15/16 12:45 PM

Update... dug a little deeper... this box is part of the suvlights.com harness, it's a switching module I believe.
I'm going to rewire them to eliminate the boxes and do away with the all filaments on feature.
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