W124 M104 Engine Harness LHD/RHD

[S80]

I recently tracked a rough idling problem down to a faulty purge valve (sticking open), but also noticed that the insulation at the camshaft position sensor connector had disintegrated - leaving exposed copper conductors

I now assume that the rest of this infamous harness is bio-degrading, though no ill effects occurred when changing the spark plugs. No fault codes have been registered, either.

There's always the risk that further checking of the harness will actually bring about its demise, so I'll probably play a 'wait and see' game - though obviously sooner or later the inevitable will happen :evil:

My question then is: is the M104 engine harness different between LHD and RHD models? The relative strength of the pound over the dollar makes sourcing from abroad more attractive, as I'm pretty confident about fitting it myself. Is the LHD engine management ECU on the other side of the bulkhead, or can the same harness accommodate either position?

Sadly, the car (a '93 280E) is worth less than a dealer-fitted harness, so I need alternatives!!

Cheers,
David

 

[Myros]

I can only speak for the W202 ( lhd)

and they are definitely handed. My ECU is on the offside, and the brake servo is on the nearside, in front of the driving position. This must make some difference to the amount of cabling used.

 

[S80]

Thanks for the quick reply, Myros - but it's not what I wanted to hear

Might have to knit one myself!

 

[Juddian]

Be careful playing a wait and see game S80, with no proir warning our very low mileage coupe's loom dismantled itself and took the ecu with it so it wouldn't be lonely....i'd like five quiet minutes with the brain donor who designed that piece of engineering madness. Brian

 

[Bolide]

Sadly, the car (a '93 280E) is worth less than a dealer-fitted harness, so I need alternatives!!

That's an interesting - and rather sobering - perspective

The looms are suitable for DIY repair in my opinion. It's only the connectors that will be a struggle. I'd make a start asap

Heatshrink with adhesive inside and a heat gun are your friends here - get tooled up for the job and do it properly

Nick Froome
www.w124.co.uk

 

[kth286]

S80

You are confused regarding left hand etc.

It really does not matter one jot.

You can buy any part, left or right hand, from any Mercedes dealer in the world for your car.

If you feel that you can get a better price for your engine loom at a dealer in France or the States of USA, so be it, just contact the relevant dealer in that country, and if they do shipping to UK, place an order.

You need to give them your VIN and they will procure the correct loom for your model of car from Germany in the usual way.

 

[MotardMan]

I'm sure you can order via the German, or USA dealer. In the UK, dealer spares are extortionate, partyl due to the fact the dealer buys the parts and gives you a 1 to 1 exchange rate for the Euro.

I'd be VERY interested in hearing how much a loom can be sourced for from an EU source outside of the UK. I am going to have to face the job myself at some stage....

 

[MotardMan]

Parts info

This page is quite useful if you want to get quotes for part numbers and cross reference them. I will not have the time to do it today, but may have time over the weekend.

http://tinyurl.com/383w2m

 

[S80]

Thanks for the advice, guys

As an electronics design Engineer I don't have a problem with modifying or adapting bits of wire and connectors, but as Nick mentioned the connectors can be tricky to deal with (getting the correct contact inserts etc). Maybe it's going to be a case of 'physician, heal thyself!'

Thankfully, the car is not a daily driver so in principle I could as a last resort re-build my current loom.

It would be interesting to speculate the cost of assembling a car with components sourced entirely from the dealers spares department at 'retail' prices !!

 

[Cosworth]

I mate, I have another harness if you want, email virdi@excite.com

 

[kth286]

S80

Someone did that excercise with a Morris minor once.

It was a car costing something like £900 when in production.

The parts costs came to something extortinate - like multi multi £1,000's.

I belive it was around 10x purchase price.

A loom is something of the order of £550 depending on spec of your car (important) plus Vat.

Ask for discount. or get quote from Bologne and go over on a cheap day return ferry.

A member of one of the forums thought exactly like yourself and tried his own fabrication but gave up and bought a loom.

The main problem is in the area you cannot see, ie the feeds to the coils under the top engine cover.

You need to cut away the outer insulation fabric type cover and view the hard cracked insulation underneath.

When your car runs on 4 cylinders and a coil has blown that is the time to worry, as that coil feed will have shorted on start up.

This only has to happen a couple of times and you are at risk of blowing the output drivers inside the main engine ECU (about £1,000). Do not ask me how I know.

I tried to patch my loom. Also electrical background. Learnt my lesson.

I would not buy a secondhand loom.

 

[MotardMan]

I tried to patch my loom. Also electrical background. Learnt my lesson.
I would not buy a secondhand loom.

I'm convinced. I'm off to Belgium in October, I'll source one over there if I can.