Dash light fuse keeps blowing!

[Tismael711]

Recently picked up a 318is...i discovered the dash lights were not working so i checked the fuse and sure enough, it was blown. I replaced the fuse and the dash lights worked, with the headlight switch in the parking light position. However, when i turned on the actual headlights.....the dash light blows its fuse again. I'm sure there is a short somewhere...and i pulled the fuse box to look underneath to see if any wires were damaged. Nothing obvious, everything looked good. Next i plan to take a look at the actual headlight switch. Any advice? Anyone have this problem before and figure out the fix?

[JGE30]

what fuse?

[Gregs///M]

Yeah pull the headlight switch and inspect for shorted wires or pinched wires. Also check in the engine bay from where the wires lead to the headlights. The short can just as easily be in the engine bay.

[dogsbark26]

The headlamps are not shorting. The dash lighting circuit is shorting. That means the problem is not in the headlight circuit. The problem is in the dash lighting circuit. And, because it happens when you switch from parking lights to headlamps, my guess would be right there at the switch. AFAIK the switch is the only place the two circuits are nearby one another. Your description leads me to think there is a momentary short on the rheostat controlling the dash lights, that occurs when switching between parking and headlamps.

Replace switch.

[Tismael711]

Thanks Dogsbark...i figured i would replace the headlight switch. Now the task of finding a used one.

[Tismael711]

Apparently its not a fuse...maybe a relay. I discovered that not only was the dash lights out....but the rear passenger tail light and rear backup light is out. What size fuse is supposed to go into fuse # 25 and 26? Bentley for E30 doesn't cover 318is or M42. I need some help. Any advice?

[Gregs///M]

I've seen damaged insulation on the wires leading into the trunk lid and near the rear taillights. Might be worth it to pull off the rubber boot leading into trunk lid and areas near taillights and inspect for wire damage.

[Tismael711]

Found a used switch...swapped it out with the help of my buddy Pierre and presto...everything works again.

[dogsbark26]

Woo hoo! Glad you got it fixed and are happy. Thanks for reporting back.

Really? The headlight switch was causing one side tail lights and reverse light to malfunction? I can't think of any way the reverse light is connected to the light switch.