W124 M104 High Idle No CC
 

Hi All,

Been struggling lately to fix the idle on my E320 wagon (Idles 500rpm too high, cruise control won't work). The existing throttle had a broken position sensor so I replaced it with a good one. It did not fix the problems, so I am wondering if I didn't do the adaptation properly or if it could be something else.

Having said this, I have 2 questions:

1. Anyone have tips for the throttle adaptation? I followed the DTC manual but I don't know if it worked.

2. Anyone have a procedure to test the EGAS module? It was working fine before the old throttle went, but I guess it could've been ruined by driving on the broken throttle for ~8 months. I am going to try and pick up a good one, but a test would be good.

Have the upper/lower harnesses and ETA been replaced by non-stop Eco junk items. High idle and a dead CC are sure signs of a bad ETA.

Good luck

Jayare

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Upper harness and ETA have both been replaced. Have not done the lower harness but it looks ok.

The lower harness wouldn't impact high idle, dead CC etc. It runs to the alternator, oil pressure and level sensors and starter.

Is the ETA a post 1998 date code or reman?

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Might be cruise control not canceling out and stuck in mode

The ETA is a 2001 mfg date, I just picked it up a few weeks back.

Gonna try swapping the stop lamp switch later today see if that works.

Have you checked the fuses in the base module?

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If by base module you mean the fuse box, then yes all fuses are good. They're all the copper ones as well.

The base module is in the coffin box (where the battery would be on 6 cyl cars). It is the only module with fuses - 4 blade fuses.Jayare

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I will have to look in that part of the engine compartment to find something with 4 pronged fuse and check.

Don't bother. I just realized your motor isn't a V8.Sent from my XT1710-02 using Tapatalk

Good to know, saves me some digging.

Ok, thanks to many here I have figured out many things that are not causing the problem. Thinking it could be a computer or relay but not sure which... Maybe the ECU?

Details are below if anyone has suggestions.

-Cold idle ~1000 P/N warmed up ~1500 P/N; no cruise control
-Codes: DM:5,6 Pin 8:8 Pin 14:2
-Upper harness is newer Delphi model, throttle swapped w/ 2001 non ecojunk
-Fuel pressure regulator, purge valve are good
-OVP is 2yr old, fuse is good
-DIY smoke test showed slight vac leak @ EGR...tested w/ mighty vac lost 3mm HG/15 min
-EGAS swapped w/ known good, no difference
-Stop lamp switch new

I recently had the same fast idle on startup issue on my 1995 E320. The cruise control also did not work. It turned out to be the T/LLR module, which is the electronic control module on the inside of the car under the passenger side front footwell. My unit was also clicking rapidly, which helped me to locate this part as the cause. Good used ones are available on eBay (the part number for mine was 1245455532). I bought one there and replaced it and everything runs fine now, including cruise control.

I tried swapping with a known good module and it did not change the situation. Figuring I will swap all the vac fittings incase it is a lot of little leaks and maybe try swapping the main computer.