Fuse 23 Blows Shortly (pun intended) After Running Lights Are Turned On

[BMWtyro]

There is an apparent short in Circuit 23 because when I switch the running light on the 7.5 amp fuse blows within a minute (up until recently it was blowing more slowly --- probably meaningless). I have checked the right-hand front and rear lamp sockets for sources of resistance (dirt, corrosion, damage) and found none.

Does this symptom sound familiar to anyone so that I might not have to tear the entire car apart hunting for a short in Circuit 23? And yes, I have the ETM handy.

Jeff

[DesktopDave]

Did you ever get this fixed? I was hoping it was something simple like a flooded rear marker light. I've seen a few times where the front wires were chafed at the left headlight cover or on the core support. Dropping the battery into that space is the likely culprit IMHO. Did you check how much current is running through the circuit?

Did you try a continuity test or test light? Remove the #23 fuse, replace it with a wired test light. I was thinking about using a spare marker light. The bulb acts like a fuse, can't flow enough current to cause harness damage. Pull all the marker bulbs (or whatever loads are on the circuit), wire up the test light in fuse socket 23, power up the circuit, then plug the markers back in one at a time and check to see which one turns the test light on. You can narrow it down to a specific harness or socket that way on many simple circuits.

I just looked at the ETM, looks like the rear markers, license and dash lights are unique to that circuit. I'd also check the Check Control circuit . It's never happened to me, but I'd think the CCC or the sensor module in the trunk could have a hard short internally.

[BMWtyro]

Thanks, Dave; I'll give it a try.

Jeff

[BMWtyro]

I finally got to revisit this problem; it turned out to be the aftermarket radio! I pulled the radio out and the fuse stopped blowing, so either its circuitry was the problem or it was chafing some wires inside the dash.

Jeff