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Old 01-27-2003, 04:14 PM
Randall Grubbs
Posts: n/a
Wiring Harness & Related Install (Longgggg)


I finished the wiring harness install this weekend and thought I’d do a recap. If anybody remembers, my car wouldn’t idle after I got it back from my tech and he suggested replacing the wiring harness. He had spliced the DS cam sensor connector back on the harness after he replaced my power steering pump plus the harness was original and at 111K miles it was time.

Harness (PN 124-440-20-06) - Replacing the harness is very straightforward, you just need to take your time and be methodical. I started at the big plug end and as I removed the old one I put in the new one so everything was routed the same. The hardest part is replacing the plastic plate in the firewall that the harness passes through. It has to be clamped back around the new harness, which is difficult. There is one screw to remove from the plate, and then looking from the engine side you can see how to pop the plate out. Basically, push on the top of the plate to pop back a prong at the top and then the plate slides up and then you can push it out away from the engine.

Breather Hoses - While doing the harness, I also replaced one breather hose. I only did this b/c it was kinda grimy but otherwise OK. These hoses are pretty stout and I don’t think they would normally need attention although they do start to get hard after a while.
-- Large breather hose (actually 3 hoses held together by 2 barbed connectors) (PNs 119-094-44-82 (hose), 119-094-71-82 (hose), 119-094-55-82 (hose), 102-094-02-12 (connector – 2 needed)) that connects the rear of the PS cam cover to the throttle actuator (TA) – to R&R this you will need to remove the mass air sensor (MAS) and the TA. To get the MAS off the TA you will more than likely destroy the rubber collar that connects them as it will be brittle and they are a tight fit. You could cut the collar with a sharp knife and rip them apart or loosen the big hose clamps and then pull out the MAS but I’m 99% sure you will destroy the collar anyway. To get the TA out of the manifold I removed the metal vacuum line that goes to the brake booster to make wiggle room. When reassembling you will need a new gasket at the manifold/TA connection (PN 119-141-12-80) as well as a new collar between the TA and the MAS (PN 119-141-01-67).
-- Smaller “Y” breather hose that connect the front DS valve cover to the middle of both heads right by the injectors. Mine was OK so I didn’t replace but it looks easy to replace without any major work. Again this hose it made up of many smaller hoses held together with connectors. Connected to this hose right by the “Y” is a line “plastic tube” (PNs 000-987-27-27 (tube), 140-476-15-26 (rubber end), 119-078-00-81 (other rubber end)) that runs under the manifold and out the front, under the DS rotor and over to the Purge Control Valve on the DS fender well. This hose draws vapors out of the charcoal canister when the valve opens. Mine was brittle so I replaced although this would not normally be necessary. If this hose broke there would be a large air leak into the engine and you might smell gas fumes from the canister.

Vacuum Lines (small white/opaque) (PNs 000-158-14-35 (line), 117-078-05-81 (rubber “elbows” 2 needed on ends) - I only replaced 1 vacuum line, all the others looked good. The one I replaced runs from the lower intake behind the TA in the middle back, out the front and down under the DS rotor and over to the ignition module on the DS fender well. Mine was toast and it was the reason my car wouldn’t idle. You could replace this easily by only removing just the MAS or maybe by reaching in the back of the engine under the upper intake (I didn’t try it but it looks possible). All the other lines on my car look OK and are as follows:
- 2 vacuum lines coming off the top intake in the back. One goes down to the pressure modulator on the tranny and the other runs up to the DS by the fuse box to the up-shift delay valve for when the engine is cold. This one also connects to the reservoir. There is also another line from the up-shift delay valve to the tranny.
- Vacuum line coming off PS front that goes down to EGR and Air pump valves (located on PS fender well by window washer solvent) and then a return line to the EGR valve (PS right front of engine under front engine cover). There is another vacuum line in there that goes to the air shut-off valve for the air pump.

In addition, there are 2 plastic wire bundle holders and a large 18mm rubber coated metal wire bundle holder (screws into rear PS valve cover) that will break. I just ordered them today at the dealer and I don’t know the PNs. Each breather hose also had a plastic holder (total of 2) that will break. I also replaced that stuff that wraps the hoses and wires over by the DS fenderwell so it all looks new.

I got nervous moving the TA around b/c it has a big cable running to it and maybe it would fail if it were moved too much. Cable looked to be in good shape and was very pliable but I would still move it around as little as possible.

Can’t think of anything else. To sum it up all I really needed was a new vacuum line and the harness was OK as long as it wasn’t moved around but it was time anyway. The outside cover of the harness was still like new but the individual wires were starting to lose their insulation. At least I got the chance to clean the top of the engine and make everything look new.

Last thing, does anybody know if the EGR valve is a maintenance item on our cars? Maybe just inspect or clean (carb cleaner maybe)??

’94 E500

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Old 01-30-2003, 12:35 PM
Registered User
Join Date: Oct 1999
Posts: 1,562
Randy- thanks for posting! I'm sure many will use it as a guide!

How's your E500 running now?

best regards
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Old 01-30-2003, 12:39 PM
Randall Grubbs
Posts: n/a
Runs great just like before and now I have no PS fluid leak and don't have to worry about the harness shorting out.

Its always great when you do that first start-up and it fires right up after a major project!!

'94 E500
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Old 01-30-2003, 03:28 PM
Registered User
Join Date: Oct 1999
Posts: 1,562
True!, true!

...and especially satisfying when you did the repair yourself!

best regards
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Old 02-01-2003, 01:59 PM
Jim's500E's Avatar
Large Member
Join Date: Mar 2001
Location: Manchester, Connecticut
Posts: 1,325
Great job...Mr. G....I think you could have the 'shop' here post it in the DIY. You'll save all of us big dealer dollars now.

I will certainly try this now myself with your instructions and comments...thanx much !!!


1992 500E
2007 CLK63
2003 Audi RS6
2001 Audi allroad
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