1995 E300 Diesel LOWER Wiring Harness - PeachParts Mercedes-Benz Forum

thatguy · #1 10-28-2015, 10:42 AM

Hello,

I was having a hard time locating the part number for the lower harness on my E300. It has a weird no-start issue with a new neutral safety switch and what seem to be perfectly intact and aligned shifter bushings (the gear selector is very precise and has no slop). The upper main harness is new MBZ and is good-to-go, but I was wondering if anyone knows the number for the lower harness? I found info pertaining to the lower harness for the gas engines, but not diesel.

Any help would be great.

Thank you!

Jeremy5848 · #2 10-28-2015, 11:42 AM

EPC shows only one engine cable harness for the '95 E300D (124-440-40-32). A cable associated with the transmission is (124-540-63-10) called "Cable harness, starter non-repeat and back-up light switch." Since you have a no-start problem, that one would be worth looking at.

I had to rebuild that harness in my '96 E300D as it had seriously deteriorated and the resulting bare wires were shorting to each other and to the transmission body (ground). No fire but a lot of strange activity.

Jeremy

thatguy · #3 10-28-2015, 02:07 PM

Thanks for the reply, that very well may do it.

The problem is a bit puzzling, it hasn't happened when the car goes on short hops around town, but I drove 50 miles yesterday and it popped up again, I had to move the gear selector around a few times before it fired up as normal. It only seems to happen after it's been hot and running a while, do you suspect this harness could be the root cause?

Thanks again

Jeremy5848 · #4 10-28-2015, 06:50 PM

It could be just about anything in the chain from the ignition switch to the starter itself. Since you replaced the neutral safety switch, that would seem to be eliminated. I have had problems with 'burned' contacts in the starter section of the ignition switch; cleaning those contacts is not difficult although the switch is a little bit of a hassle to R&R and you have to be careful to accomplish the task without locking up the cylinder lock.

The problem I had with the wires in the '96 E300 affected just the back-up lights; it was actually found (read: made worse) by the shop rebuilding the transmission of that car. They did a crude but workable repair and I followed up with a time-consuming more careful repair and there have been no repeats of the problem in seven years.

Anything that gets hot can definitely cause a problem that is not seen in short drives where the engine barely warms up. That could include the solenoid in the starter itself, the NSS (neutral safety switch, already replaced), the wiring harness, the battery connections, the ground strap from engine to chassis, or even the ignition switch (less likely unless the problem is worse if the car sits outside on a hot day.

Your problem is one of the hardest to pinpoint since it works OK much of the time and since many of the potential causes are time-consuming to access and/or expensive to replace. In my two cars, AFAIK, both NSS are original, both had wiring harness problems, and the linkage in the starter solenoid failed on the '96 at ~270,000 miles. The '96 had a failure of the ignition switch starter contacts—I replaced the switch but was able to save the old one, now put away as an emergency spare.

You probably know that there's a connection to the starter under the hood, on the first firewall. Connecting one of those wires directly to the positive battery cable will engage the starter. That allows you to test the starter including solenoid with everything else out of the equation.

Jeremy

thatguy · #5 10-29-2015, 11:21 AM

Wow thanks a ton for taking the time to write all that out, it is extremely helpful and insightful, I really appreciate it.

I think I'm going to get the car on a lift this weekend with a MBZ mechanic buddy of mine and really dive into anything and everything that could be causing it, including a potentially shoddy install of the safety switch I did myself the other night.