Here's a basic tech question:

Got a 1995 C36 with a few issues and need some guidance from you learned techies.

- CEL on (haven't pulled codes yet but think it might not be useful)
- engine goes into limp mode when asked to perform
- Air conditioning out (A/C shop thinks it's an electrical problem) - all freon was released at some point by the pressure release valve
- Radiator fans flip on immediately upon starting cold engine (huh?)

I recently changed the plugs (Denso Iridiums - inspected plug wires, coil packs and ends - they all looked fine) right before all of this happened and while doing so noticed that the wire leading to the MAF was deteriorating but no other wire in the engine bay appeared to have any similar signs.

Could all of these problems be linked to the notorious bad wiring harness?

Murphy's Law??
Here's a basic tech question:

Got a 1995 C36 with a few issues and need some guidance from you learned techies.

- CEL on (haven't pulled codes yet but think it might not be useful)
>>

Techies Law :
When CEL is on, Retrieve CODES

Techies' Law understood!

The car was dropped off at the dealer minutes ago for a diagnosis.

If the wiring harness is bad, will the codes matter? I've been told by other M104 owners that when their harness went, they got a bunch of whacky codes that could not be trusted. In fact, I've also been told that some Indy shops won't even work on the M104 if the wiring harness hasn't been replaced since the codes thrown may or may not reflect the true problem.

Please shine some much needed light on this issue.

Thanks so much for your help guys!!!

Don't try to solve all the problems at once. Start by figuring out what is tripping the CEL. That might give hints as to what is going on in all the various areas.

Let us know what the dealer finds, and hopefully we can help from there...

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John Shellenberg
1998 C230 "Black Betty" 240K

http://img31.exs.cx/img31/4050/tophat6.gif

Will do. Should know something by the end of the day or tomorrow morning.

Thanks a ton, John. I really appreciate the reply!

Just as I had feared!! Dealer said that there were so many whacky codes thrown that the problem HAS to be the wiring harness. They noted degradation of the wiring harness at the MAF and other locations throughout the engine bay.

The "shop foreman" reported that the engine harness is connected to the A/C so that may be the source of my A/C problems (is this true?). He said the same thing for may radiator fans.

1995 C36 AMG Wiring Harness Part # - WA 202 540 03 32

Part lists for $1,360.

Dealer wants $1600 parts and labor. No thanks!

Phil wants less than list. Can you believe I can get a regular C280 harness for only about $600? Gotta love AMG parts...everything is double...consistent with the sticker price of the car, I guess!!

BuyMBParts (Rusty Cullens) wants slightly more less than list.

Do you guys have any suggestions on trying to reduce my expenses? Other parts sources?

Thanks so much for your input!

-drags

I read one post where somebody said he fixed his crumbling wiring assembly by replacing each wire, one at a time. I think through friends he had access to proper wiring and anything else he needed to repair the assembly. $1089 is plenty of incentive to attempt this repair! It also depends on how much your time is worth.

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95 E320 Cabriolet, 159K

That sounds like an extremely daunting task. Not to mention the technical skill one must have to ensure proper soldering, etc.

Thanks for mentioning that method but I don't think I'd be up for that.

Just wondering if there is a cheaper parts source for purchase of the wiring harness.

Input much appreciated!

I certainly meant absolutely NO disrespect. It's just that I see post after post on numerous forums asking "how much?" and no one ever seems to answer that question. Saying "it's an expensive repair" doesn't help people out much. Just trying to help my fellow MB enthusiasts from getting hosed.

My apologies if I have offended mercedesshop! My previous post has been edited to exclude exact prices.

I'm always looking for the cheap way out, so first thing I thought of was DIY. I've redone several harnesses and created one from scatch. None nearly as complex as my current W208, but it's doable and rewarding in an odd therapeutic kinda way.
If it’s just insulation breaking down then I would think insulating the existing wiring would work fine. Maybe it’s just a few tight spots that could be loosened and/or protected by some elect tape, heat shrink, zip ties, silicone, etc.

Btw, dragracer. Ever take that beast to the strip? I’m curious how it does.

Chevota, what's involved with rewiring a harness? I would imagine you'd lose the color coding of each wire.

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95 E320 Cabriolet, 159K

What’s involved can vary drastically from car ro car. Most factory wires are color coded, and if you can get a schematic you’re way ahead of the game. Remove all or most of the wrapping so you can see what’s going where, and spend some time looking at it to get a feel. You may want to give up right about them. They are only wires, concentrate Trinity…..

I use both solid color and striped wire for replacement, and create a new schematic for myself if it gets real complicated.
Now, keep in mind I've never done one as complicated as my '99 benz. I would certainly try to repair only the problem wires. Here is how my past projects usually start out: I'm trying to fix something like A/C or instrument cluster etc. After creating a birds nest of wires I start hacking wires that are not important. (You'd be surprised how many wires I've traced to nowhere.) Those get hacked out and before you know it ½ the mess or more is gone. While rooting around I find bad insulation, bad connectors, bad switches etc, that I repair or replace. Also things that I consider un important get cut as well, not important is a matter of opinion. The end result isn’t as pretty because I don’t wrap it like a mummy in 30lbs of tape, but it’s now easier to work on and trace.
Only once have I completely stripped a vehicle and replaced every wire. It was a big job, but mostly because I’m anal and soldered and heat shrinked every connector vs crimping.

Wow! I wish I thought of this before shelling out $725 for my wiring harness. I had all winter to do it. It sounds like you've restored a few MBs, or at least dug in to repair some tough problems.

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95 E320 Cabriolet, 159K

Very impressive, indeed, Chevota!

I'm definitley not skilled enough, nor have enough patience to rewire the entire engine bay but may consider freshening up the insulation at the troubles spots. Only thing is, the trouble spots, except for the location of the MAS, may present some physically challenging locations to work in. One area that is consistently malfunctioning is the radiator fans (kicking on as soon as I start the (cold) car up) and the other is the A/C system - God only knows where the bad wires are there.

Re: trips to the strip. You bet! She's seen the track quite a few times (bracket racing, mostly).

Best run (all stock) slurping sunoco 103 = 14.04 ET at 101mph

People, especially in the South, just laugh at the prospect of an MB drag racing, until they see those numbers

Then again, benzmac has shut them up real good with his own earth shattering (definitely not stock) W202.

Impressive is a big word, I just did what needed to be done. I can see you’re looking at a headache either way Dragracer. I'd still give repair a shot. Maybe you can find a schematic that will show the fan and AC stuff you need to focus on? Another option is to isolate the fan with your own fan relay and temp sensor. Maybe wire it so it comes on when the brake is on as well. As for the AC, I’ve had plenty of trouble with those. If you can’t find the problem then you can make an isolated setup as well. But I can’t say if the computer will generate a code or not with the original wires disconnected. Maybe it’s just the pressure release valve is bad? I’m not sure if I ever seen one of those, or maybe I wasn’t paying attention. Maybe a new one and a fresh freon fill will do the trick? Good work @ the strip. It gives me an et to shoot for.


Kestas: No restoration here, just fixin what needs fixin, except on the chevota. These pix explain why it needed to be completely wired it from scratch: