I took my 300SD into my electrical class today (getting a flat on my way to class) with the hopes of tracking down the short that is causing my warning buzzer to sound when I turn the blinkers on.
Here’s the problem: the #15 fuse is blown. When driving at night with the headlights on, and sometimes (more often then not) with the break lights on, the buzzer goes on and off with the blinker lights.
I started by looking over the wiring diagram. I then locate all the devices powered by the number 13 fuse. I then got my hands on a tool that surges power through the shorted circuit and causes a magnetic field to pulse thought the wire. With a small round gauge you can trace the wires thought the car and locate the short. This sensor thing was working great. I traced the short all the way from the fuse box under the hood to the trunk. Once in the trunk I found that my antenna had had some work done on it and I was excited because I thought I had found the problem... but NO. I then used the sensor again. It I was able to pull the nest of wires apart and isolate each cluster of wires. The wires with the surge in them were the 6 brown ground wires terminated on the trunk hinge support. So class was over at that point and I still don't know where the actual short is... I’m thinking its in one of the devices that is grounded thought one of those brown wires.

Here are the puzzling things. The #15 fuse is supposed to power the seats... but there is not #15 fuse and the seats work fine.

also the "warning system" is powered via the #15 fuse... assuming they mean the warning buzzer... well its working so that is also suspicious.

The only thing good about taking my car into class today is I met another MB Diesel lover. There is this quiet old guy in my class who is from the Ukraine. He doesn’t speak the best English, but he was telling me stories about driving his 240D from Germany to the Ukraine and about how he kept it running for over 500,000 miles.

does anyone have any ideas about what could be causing the short?

Check the ground points and straps for corrosion and tight/loose fitting.

http://mb.braingears.com/126_DISC1/program/ETM_300SD.htm

__________________
Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.