Wiring Harness Swap
 

I have a 1994 E320 and I need a new wiring harness. There is a short affecting the number 6 cylinder and causing an intermittant miss. The part number that I need is 124 440 5632. The cost is about $900.

The dealer tells me the the part of the harness that usually goes is the fuel rail and coils, mostly the coils. I figure that the wire that is most likely shorting out is either the one to the number 6 fuel injector or the one to the coil that serves cylinders 1 and 6. Is there a definitive way to find out besides replacing the whole harness. I would like to try to fix the harness for now, until perhaps I can find one on Ebay or from a wreck. I just don't want to start opening it up willy nilly. I would rather like to find a way to pinpoint the break. Is there a tool that I could use to run over the outside of the wire that would find the break?

Thanks,

Charles Schwartz
1994 E320 Wagon, 118k, new headgasket and timing chain

if it's really shorting out, the ecu may follow. been known to happen. only way to find the problem is to open the whole thing up. the damage may be buried at a bend someplace. better off getting the new harness now. good luck, chuck.

I've followed the threads concerning the wiring harness issue. I've never heard of the wiring harness being sold on eBay, or anybody using one from a wreck (you'd be replacing junk with junk).

I see you have a new headgsket. Your story is typical. This job requires lots of manhandling of the wiring harness. This manhandling probably spalled lots of insulation off the wiring. Open up part of the wiring harness and take a look -- you'll be appalled! Personally, I don't think it's worth looking for the individual fault. Even if you find it, you have a wiring harness with brittle insulation throughout. More problems are sure to follow.

What Chuck wrote should weigh in heavily. A bad wiring harness with future shorts can take out some expensive equipment.

The 124 Bible refers to Fixing
 

I agree that the headgasket job caused the wire insulation to fall off in various places. I don't agree that any haness from a wreck will be bad. What if the owner replaced the harness before the crash? Are you saying that the only cars that get totalled are cars with the original harness?

There was a harness for sale on Ebay a couple of weeks ago. It was sold for $150. I contacted the buyer and he said it worked fine. There is a brand new one, in a sealed bag, on Ebay right now, for the E300D and they are asking $300.

According to the 124 Owner's Bible, it is possible to repair the harness. If more economical solutions are not found to deal with known problems, then the cost of repairs can quickly meet or exceed the value of the vehicle. If you add up the cost to repair the evaporator, head gasket, throttle acuator, and wiring harness you could be looking at $10,000 from the dealer. That exceeds the value of many 94-95 E320s. The end result will be a loss in value to the owners of these cars because of the high cost to repair known problems.

To me the bottom line is, if I have a wiring harness related problem and I repair that problem and the problem goes away, I am satisfied. That doesn't mean that the harness has to be perfect. Even if the insulation is cracked or rotten, if it hasn't fallen off and it is still insulating, that is OK. The perfect is the enemy of the good.

Good point! But it would seem like a daunting task to find what you're looking for. You'd need to locate cars with the exact wiring harness such as yours, then find one of those that has the replacement unit. Plus, there were two different engine wiring harnesses used for the 94-95 E320s. There was a change made during the 95 production.

Also, I wouldn't trust a salvage yard to determine if the wiring harness is a replacement unit or an original harness. You'd have to inspect it yourself.


True.... for some people. If this were true for everybody, we wouldn't be seeing cars on the road over 8 years old and with over 80,000 miles. This is a personal decision, not always an economic decision. Unfortunately, the trend with repair costs for modern automobiles is making this a reality where virtually nobody will be able to afford to keep a car beyond warranty.

I too had a 94 124 with a bad wiring harness, and put several weeks, just tinkering, into repairing it. It was great fun and I got it to start again, and it ran fine for about a month, then it failed again at an inopportune time. I came to the conclusion that repair was not viable. Once it is bad enough to short out in one place there are many places that are marginal. And just moving it around to repair is likely to cause more failures. I don't know where you're getting the $900 number but I paid $430 for mine a year ago. MB prices are in the opposite of freefall, but I would think you could find a new one for around $500. Have you tried Caliber? It is unfortunately a MB sourced part.

Mercedes Came Through on Harness
 

My Service Advisor just told me that the Mercedes Regional Rep has agreed to go 50-50 on the cost of the harness. I think this is fair because the car is ten years old and has 118K. The advisor is also looking into giving me a break on the installation cost since the damage occurred as a result of the head gasket job. Good Job Mercedes! I thought this was a nice gesture.

So now the issue of tracking down the broken wires is moot.

Damn - 118k and ten years - you're good. Either that or you've paid them an awful lot of money in the past.

To Quote Goethe
 

Treat people as if they were what they ought to be, and you help them to become what they are capable of being.
--Johann Wolfgang von Goethe

Actually, I just bought the car. My first Mercedes.