W124 Engine bay wiring looms

[grober]

Not sure it's all heat related - I had a Daimler Double Six for a while and that ran so hot under the bonnet in the summer, there was a heat-haze coming off it in traffic!
That had no problems with wiring, even after 15 years and as far as I know, it's still going strong back in England. Though possibly not as reliably as a Merc....

Most of the electrical side of those was by "Lucas, Prince of Darkness" which doesn't have the best reputation for quality.
I'm sure the product used for the insulation on our mid-90's Mercs was to blame as there's such a spread of problems round the world, even in cold places, it's not just a few bad looms. Certainly, heat wouldn't help but if it's the wrong stuff, it's the wrong stuff!

Paul

Sorry wasn't clear about this - the problem lay with the insulation which was designed to biodegrade quicker in landfill sites for environmental reasons . Unfortunately due mainly to heat stress it began to degrade quicker than designed while still in the car!!! The wiring from which the looms were built, was I believe, made by the same Joe Lucas but used different polymeric material than the older stuff.

 

[coupe deville]

Just ordered one from MB Eastbourne [ re first post ]. No choice really, the more I peeled back the tape to inspect, the worse it got . £737 inc vat OUCH but the head gasket has been done and 2 new front wings so its a no brainer. I'm not starting the engine until I've replaced it as a precaution as to what I have disturbed. Looking at the how to at Peachparts PeachPartsWiki: W124 Engine Wiring Harness Replacement It looks like the throttle body wiring wont be part of the new harness as it looks hard wired in the pic, can anybody confirm that.

 

[mejermy]

Beforer lashing out schekels on a new throttle actuator you might wish to look at searching on Google for 'M104 Electronic Throttle Actuator Removal, Insulation Inspection and Rewiring Guide by G. Culler'. This should lead you to a link, which, on opening, will allow you to download a great DIY PDF on rewiring the TA. Much simpler than a full harness rewire, and a massive saving. I'd attach the PDF myself, but haven't a clue how to.

 

[coupe deville]

Good find, my engine harness needs replacing, not sure about the throttle body wiring, I might just pull it for a looksee, if it's not part of the main engine harness then it might need replacing but it is on the intake side of the engine which is a cooler area

 

[pupsi]

I'm having to rebuild the top harness (injector loom) on my 124 E500 119 engine. Opened up one of the sealed round plugs, all the wire insulation has turned to dust. The throttle actuator wiring on my engine is seperate from the top harness, if thats any help to anyone.

 

[d w124]

Pupsi:The m119 ones are much cheaper to buy than the ones for m104,just so you know

 

[coupe addict]

more loom woes

I'm trying to replace the loom on my (adored) e320 coupe, 1994, but without getting a mortgage. I bought a loom for a U.S. model 94 coupe which seems to be identical in all respects except that it has no wiring for the throttle actuator.
I anticipate that this could cause some problems driving the car so I'm thinking of grafting the 8 pin ETA wiring from my old loom onto the new one, which seems to have 8 less pins utilised on the ECU multiway connector which might (in a simpler world) correspond.
For this I would need to know the pinout for the connector, and also how to enter the sealed connector without destroying it.
Any information would be gratefully received.

 

[grober]

http://www.autolib.diakom.ru/CAR/Mercedes-Benz/1995/E320/SYSTEM WIRING DIAGRAMS/

 

[kth286]

I'm surprised the loom is similar, because the battery and ECU is different side of engine compartment to our UK models, but the engine is same layout.

I guess you will just have lots of slack in the cables near the bulkhead.

I find your post confusing, as I cannot imagine a missing set of wires to the plug which attaches to the throttle under the inlet manifold. Are you suggesting the US models have a seperate set of wires (a mini loom) for the throttle ?

 

[coupe addict]

wiring loom pinouts

Many thanks - I'll try to relate the diagrams to the physical items I have and then may need more hand holding - this is particularly scary for me because the loom+ECU problem seems to be the most common cause of premature write-offs, so my attitude is not as positive as it should ideally be.
Has anyone taken one of these massive multi-way connectors apart successfully?

 

[coupe deville]

When I stripped out the old harness from my coupe the throttle body connector didn't come out with it , it is on a separate loom that runs around the nearside wing, near the abs pump and turns up to the throttle body, passing under the inlet manifold. It doesn't go near the hot side of the engine, I inspected it and its fine. I queried this when I ordered a new loom from the dealer and was told there are many different looms, depending on options like cruise, asr, aircon etc. Also some peeps ordered their new car and didn't spec a certain option and then changed their minds and that can that can throw a spanner in the works. MB have standardised the replacement looms to 3 or 4 and if you order one you will get what will work for your particular car, mine is running better than its ever done while I've had it
All I need now is everything to do with the aircon replacing and a new rear screen, SORTED

 

[coupe addict]

loom variations

On my old, fried, loom, the throttle actuation seems to take the longest possible route from ECU to ETA, via the injectors - perhaps to maximise the its bio-degrade potential? Its encouraging to think that one day I might actually get this to work and see some benefit - unforced jobs where you have to start by tearing your perfectly good car to pieces aren't great.

 

[Marcus Smit]

hi Coupe do u have a wiring diagram for the throttle body for the W124 111 engine 220E pls

 

[coupe addict]

almost a loom

The link posted by Grober in this thread about five posts back should also get you to the other e series models of the same period.

I now have a car which starts and drives without apparent difficulties, but which will not idle ( I can't keep it running below 1000 rpm ). Given the mess I made of the job that's better than I deserve, but I could do with some ideas on how to move on from here.

I seemed to have a spare two-pin connector at the very front of the engine which is one of the set behind a plastic shield immediately aft of the fan. Any idea what I might have missed?

The throttle wiring confused me considerably, not least because two of the eight wires were brown: I'm hoping this means both were earth lines, because I managed to confuse the two. One of the two led to the 44pin ECU connector block, but one was looped back to a two pin connector within the battery compartment. Could these be related to the idle problem?

The eight wires in the ETA sub-loom were all single colour and faded so as to be hard to distinguish: this smacks of a hasty design modification on my 94 model year 320 (with the older pattern AC), possibly related to the cruise control - one might have expected this sub-loom to lead to the cruise control control module rather than the ECU. Any ideas?

I'm grateful for the help members have given me so far - but still in need.

 

[Marcus Smit]

Hi all... i need help with my merc 1993/94 220e 124 111 engine multy valve. problem wont idele and cuts of at times, was towing my caravan & engine just stopped ideling was able to get home this was about 2 months ago. i tried replacing the throttle body no joy. over the 2 months the engine will idele at times but most not, some times when driving at 2000rpm the engine will just shut off, if i press the throttle harder the engine will accelerate but while driving the car on the highway she runs very well no misfire but when i come to stop will not wants to stall. when stopped will not idele i`m now looking to replace the MOL unit. on cold start she will idele at 1000rpm for a few seconds then dies, start again and it does same. P.S the origanal throttle body wiring has been redone/replaced not sure when as i`ve only had car for just over year now...please if someone can help...thanks

 

[charlettephylli]

[/IMG]


This question has probably been asked before, but here goes. I have just purchased an August 1993 E280. I have read that W124's of a certain age had problems with the engine wiring harness.

Question: Does my car potentially have one of these dodgy harnesses or can anybody tell me the Chassis No's of the cars it effects?

Question: I have also read somewhere, that if your car is effected, its worth having a chat with MB as they may contribute towards a new harness as long as the car has always been serviced by them.....in my case, I'm lucky as I have full MB service history......can anyone comment on these rumours?

 

[grober]

Yes its possible your car may be affected.
No --can't tell you the exact chassis nos--- nobody can.
MB will not contribute to the cost the of replacement of a wiring harness on a car that's almost 20 years old. The bonus is that you still purchase one from them.
Sorry to be the bearer of bad tidings but its possible if the car has a solid service history its already been replaced?

 

[BoyracerAU]

I am not familiar with E280s, but I can tell you that the wiring loom in my E220 bore the date of manufacture and part number on it.

This white sticker type tag was located in the battery well.

Cross your fingers and go and stick your head under the bonnet.

 

[neilrr]

Question: Does my car potentially have one of these dodgy harnesses or can anybody tell me the Chassis No's of the cars it effects?

All of them.

Question: I have also read somewhere, that if your car is effected, its worth having a chat with MB as they may contribute towards a new harness as long as the car has always been serviced by them.....in my case, I'm lucky as I have full MB service history......can anyone comment on these rumours?

Mehehehehe. Good one!

 

[spanner]

Quote:
Originally Posted by charlettephylli

Question: Does my car potentially have one of these dodgy harnesses or can anybody tell me the Chassis No's of the cars it effects?

All of them.

For clarity:
All of them with the multi-coil set up on later M104 engines (which a 1993 280 will be).
Earlier cars with M102, M103 and early M104 didn't have this problem.