1994 C280 -- New Wire Harness -- STILL won't start - PeachParts Mercedes-Benz Forum

brookspw · #1 08-13-2006, 04:03 PM

This all started several months ago. Occasionally, the car wouldn't start. It only has 60k miles and runs great. It cranks just fine, just doesn't "hit". This might happen once or twice a week. Generally, when this happens, if you try it a few times (sometimes 5, sometimes 30) -- it will finally "hit" and start up immediately.

It has NEVER stalled and run quality is superb. It is almost like you have all of the spark plugs unplugged -- then plug them in and crank it.

So, I took it to the dealer. After much diagnosis, they got a code for the crank position sensor and replaced it. All was fine for 3-4 days, then, same old thing.
Took it back. After 3-4 days, they said 2 things:
1 -- They were getting a code for the rear oxygen sensor.
2 -- The wire harness needed to be replaced at a parts and labor total of $2,200.

It is my opinion that the sensor would give your run quality issues but not the intermittent starting problem. The harness, though, could do just that.

This weekend, I replaced the entire engine harness. Part from Phil at Fastlane for $640 and 3 hours of my labor. Later in the day, after about the 10th start -- it did the exact same thing again!

Guys -- what can this be? I did read somewhere that it could be the OVP and that you might try tapping it when this happened. It happened again today and I tried it 10 times or so to no avail. Went and tapped the OVP and it fired right up!?

Could it legitimately be the OVP or was that coincidence?

Any productive thoughts or suggestions are appreciated.

suginami · #2 08-13-2006, 04:28 PM

I'd replace the OVP if it is the original part #.

It is a known bad part.

Arthur Dalton · #3 08-13-2006, 04:34 PM

http://www.peachparts.com/shopforum/showthread.php?p=732944&highlight=blues#post732944

If your relay is "Siemens" , change it.....

brookspw · #4 08-14-2006, 04:46 PM

Quote:

Originally Posted by Arthur Dalton

http://www.peachparts.com/shopforum/showthread.php?p=732944&highlight=blues#post732944

If your relay is "Siemens" , change it.....

It is a Siemens, so I will.

Now, how about my O2 sensor question? Could that possibly give a symptom like I have? I can't imagine it would.

ILUVMILS · #5 08-14-2006, 10:20 PM

I'd replace the OVP whether it's a Siemens or not, old OR new part number. The "new" OVP can still fail, causing intermittent crank/no-start problems. I've seen this happen many times. Just because it's the lateat, greatest OVP doesn't mean it can't go bad.

msethk · #6 08-14-2006, 10:46 PM

how did the old harness look???

Nate · #7 08-15-2006, 01:08 AM

still got it?

brookspw · #8 08-16-2006, 10:49 AM

Quote:

Originally Posted by Nate

still got it?

It looked pretty bad. Very "crispy" and brittle. A couple of the connections cracked upon removal. Saw many exposed wires. This car has only 60k miles.

Only took me about 3 hours to replace. 1 hour of that was figuring out the big hookup just behind the left headlight. It fed 4 different wire pin connectors to the new harness. 1 of those 4 wasn't in the new harness and getting that one was a pain.

Yes, I still have it.

Can anyone comment on my question regarding the O2 sensor?

Arthur Dalton · #9 08-16-2006, 10:56 AM

The rear 02 code should clear after you solve the problem and the cat heats up and burns off the mix. ..
Again, I would Change the OVP.,

brookspw · #10 08-16-2006, 11:07 AM

Quote:

Originally Posted by Arthur Dalton

The rear 02 code should clear after you solve the problem and the cat heats up and burns off the mix. ..
Again, I would Change the OVP.,

Phil has the OVP on the way. New part #, Siebel brand.

Explain your...explanation, above, please. Are you saying the rear O2 is not now working due to the OVP?