What is the general rule of thumb when this needs replaced/updated? I was told at 50k+ miles. Is that accurate?

 

When it needs it, the replacement harness is better and lasts longer. Just check it, when the insulation gets brittle its time.

 

Thanks

 

And where exactly is this harness so I can check it out? The previous owner replaced it already, but I'd like to check it out.

 

if it was recently replaced, I wouldn't worry about it.. It was an issue with the cars made before the mid 90's when the updated the harness was introduced. Easiest way to check if your car needs a new harness is to look at some of the sensors around the engine and inspect the wiring around the connectors. If the wiring insulation appears brittle or is cracking and coming apart or falling off, I would definitely look to replace the harness. However, it your harness is still nice and flexible and doesnt appear to be cracking or falling apart, I wouldn't waste your money on it..

 

Thanks

 

Good to know. I'd have to look @ the records but it was replaced sometime in the last 8 years, lol. I hope it was the better, updated one.

 

The brittle insulation problem has a hard time hiding. It should readily present itself during inspection.

Otherwise, I believe the general rule of thumb is that the engine wiring harness should be replaced once the problem is uncovered, then it should be good for the life of the vehicle, unless you're one of the few unlucky ones where the wiring was replaced very early with stock made from the same bad insulation.

 

rol607,

My 93 500E is still on the original harness which is now 15 years old and has 113,000 miles on it.

If you are not having problems don't mess with it. You will spend around $500 to $700 just for the harness parts unless you get real lucky and find a bargin somewhere but it is not likely.

I'm not having any problems to this point although I do have a new harness in the garage that I bought 2 years ago.

What can cause problems if you have to move the wiring to repair something else underneath. Moving the wires will break the brittle insulation and then the wires start shorting out.

 

?

 

Remove the air filter. Then you will see it.

It is wiring harness that connects to the 8 fuel injector nozzels. A single connector wire at each injector going back into a single wrapped harness.

If your car is running OK don't move the wiring just take a good look at it.
Check the connections. If it is bad you should be able to see some cracked insulation. The wires are most likely brittle and moving them around can cause damage.

 

A cracked wiring harness can short out the on board computer.

 

Thanks!

 

If I recall didn't Merc make the change to the environmentally friendly harness with the face lift in 1994 ?

 

This answer may be a little late on this thread but I know of no new environmently friendly harness.

Everybody I know with a E500E whether 92 or up to 94 is dealing with the same problem which is the insulation becoming brittle and eventually breaking off of the wiring and shorting out.

If you want a barrage of answers on this subject go to www.500ecstasy.com