My brake lights, turn signals, fuel and temp gauges have all stopped working plus some of the idiot lights in the dash are acting strange. Any ideas where to look at 1st. I,m guessing a short or ground is the problem.

Thanks,
Mark

Identifying what kind of car would be helpful.

Check your fuses. Probably fuse 12.

Sorry, it's a 1982 240D.

First thing I checked were the fuses. All looked good.

Make sure you pull each fuse out, and look at it. The clips tend to cut the ends off, so the fuse part looks good but the contact is bad. Also check the cluster of ground wires behind the instrument cluster.

__________________

I will check, thanks. Could my instrument dimmer switch have anything to do with it. I ask because the problem showed up the next day after I tried adjusting the dash lights with no response.

Those are all fuse 12. Pull it, clean it, replace it.

The dimmer (aka rheostat) is off fuse 1. A busted rheostat is a common problem. Search and you'll find how to jumper it, or how to clean it.

Some other possibilities might be a sticking or dirty hazard flasher. Cycle that a few times and see what happens.

Or - a botched aftermarket radio install. The 240's didn't have a hot wire, so they get hacked into to install one; but the radio did have a connection to the headlight dimmer, but people work during the day so that wire looks dead, or maybe as ground, so it gets misconnected with the new radio. Then someone messes with the dimmer - or the shifter lights - and kaboom - hard-to-diagnose electrical weirdness ensues.

Also - check your taillight sockets. Using the wrong bulbs in the car (eg double filament HD bulbs) can get those hot and melt. This is usually more a problem for taillights than brake lights though, since they're on for longer periods of time.

I just went through a similar situation with my 78 300SD. Fuse #4 had blown a few time but then all of a sudden would blow as soon as the key was turned on. There are 8 -10 items that ran off that circuit. I would disconnect 1 item at a time and then check, fuse would blow. I finally check the light for the glove box. I removed the assembly and inspected the wiring and found it chaffed in a few spots where it was grounding itself out. Start by disconnect each item and see if the fuse blows. Took me a few days but I found the problem. It was simple really, just took some time. There is a good chance you have a part that has failed and that is what is blowing the fuse.

Out of town today but tomorrow I'll look at everyones suggestions. I,ll keep you posted.

Thanks,
Mark

P.S. New to forum and new to MB (sort of had a 65 220SB 15 years ago). When I've got more time will post pictures if interested.

Loose Screws, Bolts and Fuses Faking Contact
Loose Screws, Bolts and Fuses Faking Contact - PeachParts Mercedes ShopForum

Instrument cluster, Odometer, Speedometer, Tachometer links
Instrument cluster, Odometer, Speedometer, Tachometer links

Hazard light switch cleaning
Hazard light switch cleaning - PeachParts Mercedes ShopForum

Electrical problems or gremlins
Electrical problems or gremlins - PeachParts Mercedes ShopForum

.

__________________
ASE Master Mechanic
https://whunter.carrd.co/

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
2003 Volvo V70

https://www.boldegoist.com/

If my Hazzard lights are working could the switch still be the problem?

I think that reinforces a problem with the fuse 12 electrical path. If the hazards work through the switch, that draws power from the "always on" fuse 2.

It's also possible that your ignition switch could be going bad. The switch routes the power to fuse 12. Do other things like a sunroof (if relevant) or the horn also work, or are they dead?

I'd still recommend the voltmeter. That way you can see if there's +12 on the supply side of fuse 12, or if you need to trace it back further to the ignition.

Yak, it was fuse #12. When I checked the fuses the 1st time I did't remove them just looked at them while still installed. Guess I'll know better next time.

Thanks,
Mark