M104 E320 Engine Harness Help
 

Hello,

It seems failure of the Engine Harness on the M104, E320 DOHC 6 cyl engine is rather common. The car, a '95 wagon, has the more expensive one -- about $800 at the dealer -- don’t know if that adds complexity or not. My question is how hard is this to do, and what pitfalls or 'out of spec' procedures might I be getting into? I understand it's about 3.4 hours labor fromt the MB shop manuals, so I need to figure a day (including lunch, a trip to the swimming hole and the parts shop).

Thanks!

Help!

The wiring harness is the same on all M104 W124's, irregardless if it's a coupe, sedan, or wagon.

If you purchase it here on PartsShop, I believe it's about $550.

Give Phil a call on the 800 number tomorrow morning.

David, you may have already checked this, but there was a break point in 1995 where MB improved the wiring harnesses and some 1995s don't need it. Have a MB dealer do a careful check using your VIN number and you may just get lucky . . .

Richard Easley
Waco, Texa

Richard, thanks. Is it later or earlier M104 that don't need the replacement?. The dealer said the need the last of the VIN for the same reason you descirbe, the change in Mid '95.

Forgive me for being such an amateur, but can someone briefly tell me what the wiring harness and what are some telltale signs that it is going to fail? Also is there a rough mileage which it happens to be at? I just bought an 94' E280 so im curious.

Cheers

Christian

1989 300TE
1994 E280

Christian --

I only know what I have been told on this issue but it is my understanding that MB wiring harnesses were changed sometime in the early 90s because of concerns for the environment. Unfortunately the new insulation on the harnesses decomposes before the car is no longer needed. There was an improved harness installed sometime in 95 (I think late) but I'm not sure exactly when, so the best way to know definitively is through a dealer who has your VIN number. I don't know if these harnesses are used outside of USA vehicles, but I would think that they were used on all of them. If that is the case, then I believe that your 94 would certainly fall underneath the old (problematic) harness. Another issue is that the failure might be accelerated by living in a hot climate, though I'm not sure. I can tell you, that from the reports that I'm getting, it is not a matter of *if*, but *when* on the need for replacement.

Richard Easley
Waco, Texas

MB's position is that they never had a wiring harness problem. can you expect a dealer to help with this?

Exactly. MB has never admitted there was a problem with these wiring harnesses.

There was no recall or TSB on this issue.

I don't believe there was a cut-off, either, in mid-1995. If there is, then I've never read mention of it.

All wiring harnesses are bad on all M104 engines for '93-95. This would mean 93-95 300E's / E320's, C280's, and S320's.

I did a search on engine wiring harness on this site, and you'll get hundreds and hundres of threads that deal with this issue.

Here is an example:

http://www.peachparts.com/shopforum/search.php?action=showresults&searchid=220360&sortby=lastpost&sortorder=descending&pagenumber=2

the V8's during that time period were not immune from this either...

Also the M111 equipped C-Class (C220) cars.