Right, control of the actuator is from the EA control module aka "E-GAS" (what it says on the module). BUT the engine control module send the command to the EA for throttle position, EA then processes it and controls the throttle. This is real early engine CAN bus stuff between the ECM and EA, real groundbreaking stuff. I love the way MB is always at the leading edge of stuff but no one knows it!
Gilly

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Update:

Installed rebuilt actuator from Beckman Technologies. Cleared all codes. Car starts and runs fine but idle speed in drive is about 1500 RPM. Cruise control worked two or three times but now inop again. CEL came on again--built in test led shows code 6. Pin 8 shows code 8, pin 14 shows code 2. Swapped control module in passenger foot well with known good unit--no change. Considering giving up and taking it to the dealer......any other ideas?

Thanks,

J. M. van Swaay

Eureka! I was laying on the couch pondering why throttle would not "close" to reduce RPM..........Just remembered I forgot to hook up the throttle arm return spring. (30 minute phone interuption during installation....) Car idles at about 750 RPM.....Will clear codes again and try cruise tomorrow.

Good deal!! Hope it's fixed.

I guess you read my comments on the #%^*@ spring! Took a 1/2 hr to find the 'hole' and get it operational again.

Just saw this post and I would have recommended Beckmann from the start. I had my old ETA rebuilt by them just so I could see what was NEEDED to repair it.

I have it back and am going to post (in MENU#25) pics of the failed parts that Beckmann found. In addition to the Ref Pot (which was NOT bad in my unit) is a high current coil which was the main problem in addition to the decayed wiring.

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

Good testiment for the OBD system.. the codes you mentioned from the 3 different modules can all be attributed to a possible disconnected/broken return spring.

Cruise works. I agree about the OBD. The fault codes were what prompted the "pondering" which ultimately lead to the solution. By the way, Ray at Beckman Technologies was very helpful with this project. I strongly recommend them.

J. M. van Swaay

Finally figured out how to post pictures.........

Attached Thumbnails

     

Problem is back. Built in test led shows code 6. Pin 8 shows code 8, pin 14 shows code 2. Cruise Control inop, Idle speed 1500 in park, 1100 in gear.

Verified operation of closed throttle position switch via ohmeter across pins 6 and 10 of throttle actuator connector. Also verified wiring from connector at actuator to connector at control module via pins 37 and 20. Switch "makes and breaks" with slight movement of accelerator pedal. Verified throttle linkage and return spring--ops good. Swapped control module with known good unit--no fix.

Any ideas?

Have you verified that the engine wiring harness is good??? I re-read the thread but didn't see that question asked.

Remove the connector to the MAF; using a razor, carefully cut the outside cover to expose the outside sheath of the main wire. Carefully cut it and inspect the wiring. Since it's one of the hottest places on the car, if the wires are ok, then odds are the rest of the harness is fine.

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

Thanks for your reply.

The wiring harness was replaced by the dealer several years ago. I checked several places where failures are most often found. Wiring harness looks OK.

Update:

Everything mysteriously started working correctly again--perfect idle, and cruise control works. Spent lots of time clearing codes, resetting, etc. Also replaced some faulty wiring that is not part of the engine wiring harness. I think the wiring I replaced is referred to as the battery cable harness. It is visible just behind and above the oil filter cap. It has three wires in addition to the battery cable. (by the way, all the connectors associated with this bit of wiring are easily disassembled. I soldered together a new harness in about a half an hour) The only part of this harness that could be remotely associated with the throttle actuator is the purple/white wire that carries the "starter lock out signal" (one of the possible problems denoted by pin 14 code 2) I really don't think this was the problem, but with shorting wires, you really never know....

I'll bet you're glad!!

The only note I can add is this; all MBs seem will act strange if the battery voltage is low. One thing to observe is duing 'starting', do the IC lamps dim alot??? If so, then most MBs will set phantom DTCs, ICs lamps will illuminate, etc.

Maybe this battery wiring was 'ohmic' causing a lower voltage into the F23 module box???

A few years ago, when my battery was on it's way out, many strange IC lamps would light, my coupe's windows would lose their memory, and many other strange things.

When I started the car, the IC lamps would dim badly; I tested the battery and it was just under 12.1 volts after a 700 amp load test. After replacing it, all was fine.

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

I agree .. I have seen Low Bat V. cause all kinds of wierd havoc .
Many times it is as simple as bad ground [ W] connections.............

J. M. van Swaay

Is this the connector for the three wires? It connects to Oil sensor & Solenoid.

Bob

If the problem reoccurs, I'll monitor voltage.....

Incidently, while researching this problem, I came across some information on fault codes. LH faults (pin 8) that occur while the engine is running are stored after 4 starts. DM faults are stored after 2 trips. Faults cannot be erased by disconnecting the battery. Also, in the diagnostic information (alldata) one of the possible faults for pin 14 code 3 is "reset not accomplished actuator adaptation" The remedy is to erase the code, then reset by ign off then on for 90 seconds prior to start. I did have a code 3 once or twice during this whole process. Car started running correctly shortly after completing this reset procedure. I originally thought this reset procedure was only applicable to ASR equipped vehicles.......There are still so many things I don't know. One last thing, I found out that swapping control modules with other vehicles may not be such a good idea. Running conditions are stored in memory and ECUs are coded to a specific vehicle. Coding can only be changed with HHT. (I'll leave that to those with more knowledge than me...)

Thanks to all who posted.

J. M. van Swaay