1995 E320 fault codes - throttle actuator? - PeachParts Mercedes-Benz Forum

J. M. van Swaay · #1 09-09-2006, 04:24 PM

1995 E320, 90,000 miles, engine wiring harness replaced.

Cruise control completely inop. idle to low--about 500 rpm--occasionally dies when power steering loaded or ac cycled on.

CEL on, code 6 (Idle speed control faulty) Can clear but will come back within a day or so.
PIN 8 code 8 (Idle speed control at upper or lower control stop--limp mode does not appear to be active)
PIN 14 code 2 (2 EA/CC/ISC control module (N4/1) or Safety contact switch (M16/1s1) or Stop lamp switch or Cruise control switch or Actual value potentiometer or Starter lock-out/back-up lamp switch or engine speed signal or vehicle speed signal or closed throttle position switch or safety relay in EA/CC/ISC control module)

PIN 6 code 3, 4, 8 (don't have look up table for these)

checked stop lamp switch above brake pedal--appears OK

Dealer says: HFM SFI diagnosis: possible cause intake air leak or throttle valve binding

Is this the dreaded throttle actuator problem?

J. M. van Swaay · #2 09-10-2006, 10:21 PM

Just another related question: If a CEL fault is present but cleared without fixing the problem, how many times must the same problem be sensed prior to the CEL coming on again? It seems like the CEL comes back on after about 5 start/shutdown cycles. Anybody know the answer?

deanyel · #3 09-10-2006, 10:45 PM

Miscellaneous comments - PIN 6 is SRS so it's a safe bet those are unrelated - I would just clear them and forget about them for now. The PIN 14, #2 code you've picked up is for a car with ASR. Do you in fact have ASR? The brake lamp switch is only about $15 - if it's original it may not be a bad idea to replace it anyway. It does sound engine/throttle actuator related but it's too soon to panic.

J. M. van Swaay · #4 09-11-2006, 09:15 AM

What exactly is ASR (is it automatic slip reduction?) and how would I know if I have it?

Thanks

Gilly · #5 09-11-2006, 10:21 AM

Retards (backs off) the throttle if the wheels spin out (slip). You would have an orange/yellow triangle that comes on with the bulb test or if the wheels start to spin, and also with the bulb test you's see a warning light, I believe red square, with ASR on it.
Gilly

BadBenz94 · #6 09-11-2006, 11:06 AM

Yes you have a dead thottle accuator. If your wiring was bad on the harness it will be bad on this as well. I had the exact same problems, low idle, AC wouldn't work due to low idle and of course no cruise control. I purchased mine (noted in other posts) from www.4mercedes.com for $400.00 with a 1 year warranty. Best of luck and let us know how it turns out.

Chris

J. M. van Swaay · #7 09-11-2006, 07:39 PM

The actuator is now sitting on my work bench undergoing a rebuild. The wiring harness was pure dust. If the motor and potentiometer are still good, I should be able to make a new wire harness. Splitting the connector proved to be troublesome. Now that I know how it is molded together, I'm sure if I had another one, I could make a much cleaner job.....Does anyone have an old connector they would be willing to send me. In exchange, I'll put together a HOW TO on this project for everyones benefit. If anyone else has done this job, I'd like to hear from you. I need some help determing which motor lead is positive and which is negative.....

Thanks,

J. M. van Swaay

I'd post pictures but I'm not sure how.....

J. M. van Swaay · #8 09-11-2006, 07:40 PM

Better yet, does anyone have a source for just the connector and wire lead?

Bob Weir · #9 09-11-2006, 09:03 PM

"ASR" It's an electronically controlled limited slip differential for controlling it when one wheel loses traction. There's an idiot light labeled "ASR" in the instrument cluster on the right side.

I just went down the "throttle actuator" road on my 94 e320 and had 4Mercedes rebuild mine. I hate to be the bearer of bad news, but in addition to the bad insulation, there's also a potentiometer inside that goes bad and usually has to be replaced. That's why rebuilds have to be done by someone like 4Mercedes or Bechmann Technologies. Maybe you'll be lucky and not need the pot.

These articles regard a V-12, but they apply to yours as well

http://v12uberalles.com/throttle_actuator_rewire.htm

and

http://pages.prodigy.net/jforgione/MB_asr.html

Good luck
Bob

Arthur Dalton · #10 09-11-2006, 09:19 PM

<>>

ASR is Accelleration Slip Regulation.
It is the direct opposite of ABS. On ASR, wheel speed sensors monitor drive wheel revs and pulse lock the brake of the spinning wheel so the drive shifts to the opposite wheel. ASR systems will have individual rear wheel sensors.
It is not a limited slip differential type system,where drive power is controlled with clutches in the differential itself.
ABS uses the same sensors , except the controls are reversed where the locked wheel is released to prevent wheel skid when braking.
These both work off the brake system only. The throttle is also regulated when the slip is detected by the ASR module to restrict drive wheel power.

You can tell a chassis w/asr b/c it will have a Yellow ASR triangle indicator lamp on the dash [ center of speedo]. This will light w/key ON position.

J. M. van Swaay · #11 09-11-2006, 09:50 PM

Thanks for the help. My vehicle does not have ASR. (yellow triangle in instrument cluster is not present) I understand that throttle actuators go bad for 3 reasons: decayed wire insulation, defective potentiometer, or faulty motor. Based on what I found when I cut into the wire, I can definitely say the wiring is bad. The black sleeve around the wires leading from the actuator to the plug contains only dust and copper strands--no evidence of there ever having been any insulation. I'm going to rewire this thing and give it a try. I'll let you know how it turns out.

I'm still looking for a plug/wire lead supplier. If I can't find an MB match, I could cut off the other end and splice in a whole new connector. Only problem with this is if I do end up needing a rebuilt unit because of a bad pot or motor, I will have a connector mismatch. (Guess I'll have to keep the old connector end just in case)

Any other thoughts?

Bob Weir · #12 09-11-2006, 10:36 PM

Junk yard for the plug. There's has to be a lot on ng actuators out there. Try Potomac MD & FL locations.

http://www.mbpartsonline.com/

FYI If you go shopping for a used one, I understand when getting another throttle body (actuator) the serial number of your car is relevant.

Bob
PS I now list members would be very interested in pik of your accuator's innards. If you have digital camera, but not capabilities to post here, email me the pik, I'll format it for posting by you or me.

kidMoBile · #13 09-12-2006, 07:42 AM

Perhaps the wiring degredation leads to premature failure of the potentiometer? If so, then it may not be a bad idea to preemptively swap out the wires on an actuator that still has not acted up yet and possibly save the rest of the unit. I'm thinking about doing this on mine.
Brian

J. M. van Swaay · #14 09-14-2006, 11:28 AM

Update:

Succesfully rewired unit. Still getting the same fault codes, cruise control still inop. Suspect bad potentiometer or motor. Ordered rebuilt unit from Beckman Technologies.

J. M. van Swaay

david s poole · #15 09-14-2006, 04:50 PM

went throgh this about 4 mths ago with exact same car.customer had already had bad throttle actuator diagnosed,bought one off the web and had the man who diagnosed it fit the rebuilt one.he came to me with a worse set of symptoms than he started with. i put back his original unit and car ran better but not right.tried to access ea/cc/isc and got no communication. i guessed that the bad actuator was cause but to make long story shorter i found that ea/cc/isc has own computer in pass side floor and another one from local junkyard[$50] did the trick and all was well.i had thought all along that idle came from section in main computer but this is not the case.