94 sl500 codes and the dreaded harness rot

[edsl94]

hi fellow sl owners. i have a 94 sl w/56k on the odometer, and a 119.972 motor. upon a recent restart the car ran very poorly. got it home, read some threads, made the blink reader( it works perfectly) and pulled some codes from the 38 pin connector. they are as follows:
p4=0
p6=0
p7=6
p8=0
p13=constant l.e.d.
p14=constant l.e.d.
p17=12
p19=6
p21=17
p22=constant l.e.d.
p23=15
p31=0
pins 11,30 issued no response
upon a clearing attempt p6 cleared, p17 cleared to a constant l.e.d.,
p19changed to 7, p21 changes to a 7. also the cel cleared on the dash.

as long as i had the engine exposed i did a closer inspection of the wiring harnes and anyhting not "on" the engine looked fine. but there on top of every injector, the dreaded harness rot. exposed wires just aching to short. do i blow it up now or is there hope?

[fcicco]

I had the same problem with my 95' Sl500 w/119.972 engine. Many trouble codes - they would come and go - cel. A new wiring harness did the trick. Very simple job - about one hour. I got the harness for $550 complete. Car runs strong with no problems 140K+. Many posts on this subject. Good Luck!

[edsl94]

thanks for the reply, i know i'm not the only one with this problem.was the harness a dealer item or did you go through phil? i am going to email him and see what he can do. also, are the harnesses the same as the bad ones just new, or are they better than the original. did you disconnect the battery? i'm also thinking of reringing the injectors while i'm in there. couldn't hurt.

[fcicco]

The harness is a dealer item that does not suffer from "heat rot" or so they say. MB claims that there was no problem with the original. Funny, the dealer I used always stocks two harnesses because they fail early - fail often.
Always try Phil first - probably can get it for you. Email me for pics and more info.

[Terry McNeilly]

Yep, check with Phil . It’s not difficult at all to do the swap. Just lay the new on top of the existing and work carefully. By the way, I replaced the Electronic Throttle harness as well due to its insulation looking just as bad as the engine harness. It was more difficult to install than the engine harness because you have to remove the throttle body. Be very careful of the hot wire sensor element in the throttle body if you do that one also. It's an expensive mistake if you somehow manage to damage it.......like I did.

[edsl94]

on mine, it looks like the wiring going to the throttle body is in the same harness as the injectors and the sensors on the front of the motor. i read on one of these threads where you have to "hand wire" into something on the throttle or linkage, but i don't see anything else in that area that has a wire going to it. how about the battery? does that have to be disconnected when doing the swap? can you change the harness while the car is still "hot"? i'm in no rush to do it, i have other priorities at this time. just building up my knowledge base before i do it. thanks for the replies.