[mrerikson]

Hey all,

Sorry for starting a new thread here. I found an old one from 2008 I was going to resurrect, but can't find it now. Maybe a new forum somehow?

Anyway, my problem is that my new to me 240 is blowing the #16 fuse.

It started after I took the instrument cluster out to fix the odometer. While I was there, I figured I'd try to replace some bulbs to see what's going on at night. Replaced blinker (turn indicator) bulb and some idiot lights. Also took the center console out and replaced some with LEDs I found to fit. Can't find anything that looks like it's sqeezed or shorting.

I unhooked the bulb failure warning light Relay, unhooked the instrument cluster, and unhooked both rear tail/brake lights...fuse still blowing.

I'm not a wizzard with a multimeter, but I'm trying to learn.

Any advice?

Thanks.

 

[scaramoucheii]

Are you working with a wiring diagram, or blazing a fresh trail?

Here is a link that may be useful if you do not. There may be others out there on the web, so happy hunting.

http://www.carknowledge.info/wp-con...ram-instrument-cluster-heater-fan-sw-1993.jpg

Also you mention that you are "trying to learn" the correct interpretation of multimeter readings, one key point here may be the false positive, in that if there is an "Open" somewhere in the Circuit, you will read the supply voltage (in this case battery voltage) before the open and 0V after the open, this sometimes throws people when looking for a circuit that uses an open/closed ground as the switching mechanism.

But certainly sounds like you have a short to ground, does this happen when you turn the ignition on, or turn the lights on, etc. You state "...fuse still blowing. " but when does this occur?

 

[mrerikson]

Thanks for the reply, I've found the culprit!

I was working off of the wiring diagram in my newly acquired Bentley Service Manual, but your diagram is much easier to trace compared to what I've found so far.

To explain a little better, the fuse was blowing as soon as I turned the parking lights on with the key off. I imagine it would have blown with the key on as well, but I never got that far.

The problem was the "ashtray light" coming from the Rheostat in the diagram you provided on the red/white wire's circuit. On another forum, I found a thread pointing to LED's not playing well with the ashtray light power supply, and I figure that would be easier than pretending I know what I'm looking at on the multimeter. The LED's contacts wrap around both sides allowing contact with both terminals and the short to ground. Apologies for improper terminology. I'll just keep an old bulb in there for now.

As for me "trying to learn" the multimeter, I get to leave that frustration to another day! I'm sure there's another thread about that somewhere.