Mystery Wires... - PeachParts Mercedes-Benz Forum

dieseldaddy · #1 06-15-2002, 09:31 AM

My 1981 300TDT has a problem that has me baffled!
Every once in a while the car just won't start. Just a single click when the key is turned over all the way. The glow plug light comes on, and all buzzers and lights work fine.
Originally, thought it was the battery. Then bought new battery with same results. (Optima red top)
Checked the voltage when off: 12.6
Checked the voltage when idling: 13.8
Alternator and Voltage Regulator seem to be working.
So this happens intermittantly, sometimes twice a week, sometimes (like this last time) goes a month without doing it.

There was an aftermarket alarm system installed and removed, but most of the woring remain. There was a loose connection that I fixed, the only WHITE wire under the dash. I assume that this is the ignition wire, or the wire to the starter. (?)

Whenever the problem occurred I could jiggle the wire and it would start right up.

Well, This last time I know the wires are connected well, but I juggled them anyway and still could not get the car to start. The only way was to turn the key all the way over, then quickly do it again...sometimes two or three times.

QUESTION: What the heck is this connector?(below) It is located right in front of the battery tray, and I have seen it on other 300 series...
Below is a picture of the connector that *was* disconnected completely, but the second to last time I reconnected it but it did not seem to be the source of my problem. What is this connector? And could the fact that it is loose and broken be the problem?

One last picture: The wires appear to be going to this thing. What is this thing? It is to the left of the alternator. Is it really connected to the mystery connector?

Thanks in advance for any suggestions!
-Brian

Palangi · #2 06-15-2002, 10:00 AM

It sounds like the ignition switch is failing.

The mystery device is the auxilary coolant pump.

peterhardie · #3 06-15-2002, 11:58 AM

my guess is that the jiggling of the wire had nothing to do with the starting. I'd bet on your starter (unless you have replaced it recently), that it is in the early phases of failure. Clean all the connections, including the fuses (turn them a couple times even if they look intact, they get corroded at the ends sometimes) and see if you still have problems. If you do, replace or rebuild the starter.

Peter
1985 300TD

dieseldaddy · #4 06-16-2002, 09:38 PM

Thank you guys!
Just an update:
The WHITE wires were to an aftermarket alarm system. I noticed that the actual MB wires that were spliced were purple and white. Anyone know what these purple ones are powering?

I spliced them back together, removing the white ones. Charged up the battery and VROOM! started right up.

I have a rebuild Bosch starter in my garage that I will take to a shop and have them test both.

Here is an interesting twist...
The symptoms have been that the clock will all of a sudden loose time. Just about 15 minutes overnite. Also the turn signals will blink *faster* when idling and slow down to normal with acceleration or steady speeds. Kinda wierd as I thought it would be the other way around.

Thanks again for your help.