1995 E320 fault codes - throttle actuator?
 

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?

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?

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.

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

Thanks

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

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

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.....

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

"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

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


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.

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?

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.

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

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

95e320
 

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.

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

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.

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.........

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.

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??? :confused:

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.

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

Bob:

Yes, those are the wires I replaced. Three pin connector just above the brake booster. One lead goes to oil level sender in oil pan, one lead goes to starter, and last lead goes on back of engine top left side of transmission. I'm not sure what the last lead is for, color on wire is brown/green. I know there is a crankshaft position sensor down there somewhere....could this be it? (I looked at schematics for a while trying to find brown/green wire. I was hoping it would be something related to idle speed/cruise control.....)

J. M. van Swaay

<<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>>

The reset for adaptation mean is to erase codes until the module shows a code ! [ single flash], then hold the button for 6-8 secs, . then the key On sequence. This clears the memory back to mean after codes have been cleared.
If this is done, you do not have to wait for the ECU to relearn using drive cycles .. the poblem using drive cycles is if the adaptation was way out to begin with, then codes can still pop up during the drive cycle relearning process.
So, it is best to do manually, specially after the code fault remedy has beeen found

Pictures of the connector/replaced wires.....

JM van Swaay

Looks just like mine.

Bob

Update: the rest of the story.....

Problem is back, below is description of problem.

Installed rebuilt unit in a 1995 E320 Sedan.
Initially the unit operated correctly, 2 days later, operation became
intermittent. Symptoms are intermittent high idle speed (1400 RPM in park,
1000 RPM in gear) and inoperative cruise control. (either both symptoms are
present, or neither are present. never one without the other) Shutting off
the car and restarting will sometimes cure both problems, but they both
reoccur. Retrieval of stored fault codes (via impulse code reader, not HHT)
consistently yields the following:

Diagnostic module: code 6: Idle speed control inoperative

ECU module: code 8: Idle speed control (ISC) system at upper or lower
control stop

HFM SFI module: code 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

Out of desperation, I replaced the remanufactured unit with a known working
unit pulled from an identical fully functional vehicle. Idle speed/cruise
control now work properly. So far, there is no indication of intermittent
failure.

Returned unit to Beckmann for testing, they confirmed reman unit was defective. (the drive motor was bad)

Hope this story helps someone else........................

Before reading your 'conclusion', while reading the post, I came to the conclusion that the ETA was bad. So I guess it was.

That's a bit troubling since it's supposed to be good . . . hope Beckmann improves its final testing methods to ensure that doesn't happen again!

You have been busy! Tnx for posting your added steps.

My diagnosis was also a bad throttle actuator but I refused to believe it because it was supposed to be a fully tested reman unit. In all fairness to Beckmann, this unit probably did test OK prior to them sending it to me. Intermittent problems are always troublesome. By the way, the motor is the only part of the throttle actuator that can't be rebuilt. It is pressed in and replacement is not possible.

. . . don't forget the "Ref Pot"!

I'm not 100% sure but I think Beckmann can recondition the potentiometers. They have some kind of proprietary process were they reapply resistive material.

If you read Menu#24, specifically in the section entitled: "Update; July 14, 2005", it's fully explained.

Basically, it the Ref Pot is 'toast', then the unit is scrapped. If it's ok (or at least salvagable), it can be 'sputtered' (micro-electronic thick film term) and be re-used.