94 S350d Won't crank - Page 2 - PeachParts Mercedes-Benz Forum

wrench56 · #16 04-27-2011, 11:18 PM

So I had a chance tt do some more troubleshooting after work tonight. It wasn't as easy as a fuse. I wnet back through everything I've already done. Unplugged some connectors, reconnected them, cleaned the battery terminals, generally shook anbd wiggled everything I could. And it cranked!! Tried it a second time it cranked, but took a long time to fire and run, but it ran. I shut it down, put everything back together and it does the same thing it was doing when I started the thread. So I think it's a wiring probel. I found the glow plug relay, I think, it's solid state and don"t see any type of fuse. Any ideas??

Wayne

compress ignite · #17 04-27-2011, 11:50 PM

It's Electronically Protected.
(It disconnects itself in case of Dangerous Shorts until They're fixed)

Yeah,you've self diagnosed your problem...Wiring Connection(S)!

Time to drag out the old DMM.

CSchmidt · #18 04-28-2011, 08:46 AM

Folks,

My 93 300 SD would occassionally do the same thing. Turn the key and I think only the airbag light would come on. I never solved it but found a work around. I connected a remote starter - like you use during a gas tune up to bump the starter. I turned the key to the on position, hit the remote starter from under the hood, and the car would crank, start, then the lights on the dashboard would flash in random orders, something would reset, and all was fine again. This typically happened to me in very hot weather ( 95*) or after long drives. I suspect it was part the wiring harness degrading issue that hits these years, but I never found a definitive answer. I left the remote starter in place all the time and the 3 or 4 additional times this happened it always started the car and cleared out the issue. Hope you find the root cause.

Chuck

vstech · #19 04-28-2011, 09:36 AM

careful, as this bypasses the neutral safety switch. be SURE you are in park, and the parking brake is set before you hit the switch!!!

don't ask me how I know this...

300D85 · #20 04-28-2011, 03:57 PM

Quote:

Originally Posted by CSchmidt

Folks,

My 93 300 SD would occassionally do the same thing. Turn the key and I think only the airbag light would come on. I never solved it but found a work around. I connected a remote starter - like you use during a gas tune up to bump the starter. I turned the key to the on position, hit the remote starter from under the hood, and the car would crank, start,

and if the starter acts up or doesn't crank that way, you know you have a starter motor prob

Quote:

then the lights on the dashboard would flash in random orders, something would reset, and all was fine again. This typically happened to me in very hot weather ( 95*) or after long drives. I suspect it was part the wiring harness degrading issue that hits these years, but I never found a definitive answer. I left the remote starter in place all the time and the 3 or 4 additional times this happened it always started the car and cleared out the issue. Hope you find the root cause.

Chuck

definitely there is a know degrading wiring issue with these models/year cars (~91-95 w140) where the solution is replacing wiring harnesses $$$

you could also set up the remote starter switch inside the car

w140 Wiring Harness Replacement -- Easy? 1994 S420

w140 Wiring Harness Replacement -- Easy? 1994 S420

Quote:

What I heard is that Mercedes experimented with a different type of wire insulation (plastic) back then that was more environmentally friendly...would decompose easily when the car was eventually scrapped. There was a problem with the plastic getting brittle and breaking up much sooner than they anticipated. Larger Mercedes engines put out quite a bit of heat.

I would assume that 9 model years later (in the case of my car), they would be making more durable harnesses, but don't know for sure.

Bosch North America said that the bad wire harness and a known software error in the LS-SFI unit are known problems at Bosch for many '94/'95 models. Would probably have been recall issues on American cars.

wrench56 · #21 04-28-2011, 10:17 PM

Definetely not a bad stater. I got it to turn over this morning, but didn't have time to dick with it very much. Went over to the hangar at lunch this evening and got the car started, put in gear(reverse and drive) drove it accross the hangar and back. Didn't shut down until I shut it down. Pretty much discounts a bad neutral switch I think. The wiring harnesses look to be in good shape, the insulation isn't cracked or mising so I think it's has been replaced along the line. Still do not get any caution lights on the instrument panel and it takes a long time to start when it will crank. may have more than one problem. Anyway as soon as I can get it back together and started, it's gong to the local mechanic that at least knows what a mess European electrical systems are. I have too much else going to fool with it right now

Wayne

vstech · #22 04-28-2011, 11:15 PM

Quote:

Originally Posted by wrench56

Definetely not a bad stater. I got it to turn over this morning, but didn't have time to dick with it very much. Went over to the hangar at lunch this evening and got the car started, put in gear(reverse and drive) drove it accross the hangar and back. Didn't shut down until I shut it down. Pretty much discounts a bad neutral switch I think. The wiring harnesses look to be in good shape, the insulation isn't cracked or mising so I think it's has been replaced along the line. Still do not get any caution lights on the instrument panel and it takes a long time to start when it will crank. may have more than one problem. Anyway as soon as I can get it back together and started, it's gong to the local mechanic that at least knows what a mess European electrical systems are. I have too much else going to fool with it right now

Wayne

once the engine is started, the neutral safety switch does nothing.
this test proves nothing about the switch.

wrench56 · #23 04-29-2011, 11:03 PM

Good point! Unless the switch is as we say in aviation, AFU (all f@#%*d up) and doesn't know what position its in. Anyway the point was I wasn't able to duplicate the shutdown I originally had. THe more I ponder on it, the more I think it's the igniton switch. Just wish MB had their schematics drawn better.
Wayne

wrench56 · #24 05-06-2011, 02:15 AM

So Murphy's 5th Law of Automotive Repair, is "When demonstrated for the repairman, the appliance will work everytime." And it did. 8 bucks for a can of Graphite lube, shot into the key tumbler, and everything works as advertized! Lots of expletive deletives to follow
Wayne