1994 E320 with ASR, a little over 100k. Three cold wet mornings in a row - same thing. ASR light comes on, car goes into the limp home mode (strange throttle behavior) and LED readout gives a fault code #6 (idle speed control inoperative). The strange thing is, I shut the car off, check and reset the code, start the car again, and it runs fine for the rest of the day. I tried a new brake light switch but it had no impact. It certainly appears to be temperature / humidity related.

I realize this may point to a bad engine actuator but I'm not quite ready to spend that kind of money - it's not that bad yet and I'm not yet so sure that's the problem. According to my parts supplier he sells a lot of new engine actuators and quite often gets a follow up phone call saying "well that didn't fix it". Any "better news" ideas about what it could be?

Did it again this morning. Two more clues - 1) the ASR light / limp home mode first kicks in when I hit the brake, and 2) if I don't reset the fault code it stays in the ASR light / limp home mode, but reset the code and it goes back to normal operation. Seems to me unlikely that it's the engine actuator - why would it happen when I hit the brake? I would not mind at all permanently disabling the ASR if it would get rid of the problem. It seems such a nuisance on an older car.

Check codes from pin 8 and 14.

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Zafar
94 E320 58000 Miles

a bad ETA. Very similiar to my problem described in MENU #24 on my MB page (click the 'www' icon below).

I disabled the ASR (it's described in Menu#24) and it worked ok for a while but that didn't fix the problem permanently. Had to replace the ETA.

It's not a bad job; I did myself in about 3-1/2 hrs. Got a break on the price from one of my tech's suppliers.

It appears that the main problem that causes this problem is centered in the "reference potentiometer" assy. The material literally wears out from the continual 'rubbing' of the contact arm, so that can't be repaired. Buying a used one is not that good either since it is already a bit worn. But if you can get one from a low milage 'wreck', for a good price, then that would probably be ok.

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

Visit my Mercedes Web Page

Interesting. This recently happened to me too, on cool, very wet mornings, especially if the car has not been driven for more than 24 hours. But it also happened on Hot, humid mornings, again, if the car had not been driven for more than 24 hours.

Driving a while, then restarting, resolves the problem and the car performs beautifully. I am guessing the fault is caused by some component, such as the brake switch, becoming sticky and needing to warm up/dry out before working properly.

I have not yet replaced the brake switch, but it is now on order. Tire pressure is OK, but I have not checked for dirty wheel speed sensors. The only other issue is a neutral safety switch that is misaligned.

Since you indicated you have replaced your brake switch and the problem persists, I will assume that for me, that will be just the start of tracking down the true problem. (I would think that a bad ETA would be consistently faulty, and not just once in a while.)

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2008 E350 4matic / Black/Anthracite

------------------------------------
Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black

Never resolved, returned to Phoenix and a warm dry garage and it never happened again. Certainly appeared to be temp/humidity related but remains an ASR mystery for the ages.

I agree, there is a definite connection to extremes in humidity, and extremes in temperature. I am just glad it happens only infrequently.

I plan to replace the brake switch; clean the wheel speed sensors; and while I have the car up on jack stands, try to correctly realign the neutral safety switch.

__________________
2008 E350 4matic / Black/Anthracite

------------------------------------
Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black

Can also be an over-charging OR under-voltage problem.

You might watch the system battery voltage as the problem happens.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Code 6 on DM is telling you to go to EA module at pin 14 for EA/ISC codes.

Do it as soon as the problem arises.

PIN 14 CC/EA/ISC :
1 No fault found
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
3 Right EA/CC/ISC actuator (left cylinder bank) (M16/1)
4 Cruise control switch (S40)
5 Stop lamp switch (S9/1)
6 Starter lock-out/backup lamp switch
7 CAN data bus signal from EA/CC/ISC, ABS/ASR, HFM-SFI or LH-SFI (right or left)
control module faulty.
8 Left front axle vehicle speed sensor from ABS/ASR control module
9 Left rear axle vehicle speed sensor from ABS/ASR control module or in 124 chassis
Hall-effect speed sensor.
10 Engine speed signal (TN) from base module (LH-SFI) or engine control module (HFMSFI)
11 Closed throttle recognition signal to engine control module (HFM-SFI or Left LH-SFI)
Fuel safety shut-off to engine control module (HFM-SFI or left or right LH-SFI)
12 EA/CC/ISC control module voltage supply
13 Left EA/CC/ISC actuator (right cylinder bank) or actual value potentiometer (M16/4r1 or
M16/4r2) or actuator motor (M16/4m1)or magnetic clutch (M16/4k1).
14 Closed throttle position contact switch
15 CAN data exchange with ABS/ASR control module illogical

__________________
A Dalton

Thanks, I will do that.

__________________
2008 E350 4matic / Black/Anthracite

------------------------------------
Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black

Actually, even when I replaced my NSS, I didn't really think it would solve the problem . . . but it did.

If you read other "ETA-problem" posts, the brake switch has solved their problems also. So don't assume that it won't.

In your case, as it presents itself, I would be surprised if it was the ETA; sounds like the B-S or NSS . . . b/c it doesn't get worse. A bad (going bad) always gets worse.

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

Visit my Mercedes Web Page

As for me, I replaced my NSS a few months ago, but did not align it properly, and need to do that. The brake switch is definitely suspect since the fault has always occured immediately, or shortly after, applying the brakes.

__________________
2008 E350 4matic / Black/Anthracite

------------------------------------
Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black

This Brake Switch, where is it located? (C124). If brake light behaves normal, could there still be a problem?

Looking for new clues..., my Limp Home Mode problems since 8 years now, only appears in hot weather. So the car is stored summer (and winter) and used spring and autumn...

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-94 E 36 AMG Coupé, Brilliant Silver
-98 G 500, Obsidian Black
-05 Mini Cooper, Solid Black
-97 993 Carrera S, Ocean Blue

Would a wet coolant level sensor plug cause a short/ground that would drain the battery enough to cause said low voltage condition?

Three weeks ago I replaced a failed coolant level sensor. In addition to the disappearance of one of the float magnets, I saw that the sensor o-ring had failed, and coolant seeped into the plug, making it visibly wet. Since replacing the sensor, I have not experienced an ASR/limp-home fault under the three conditions that typically cause(d) it:

1.) Car sitting more than 24 hours without being driven.

2.) Significant Variances is ambient temperature and humidity

3.) Sitting overnight after/during a heavy rain.

All of these have occurred since replacing the sensor. Last night, and today, we were/are being hit with hurricane/tropical storm Hanna. I just knew I would see the ASR light this morning when I drove the car. But I didn’t.

Adding further support to the low voltage theory is that whenever an ASR fault occurred, the same minimal time interval ( approx 8-10 minutes) needed to elapse before the car could be restarted without re-triggering the fault. I initially thought that some component needed to warm up or dry out, but because the time interval was the same whether it was 90 degrees or 20 degrees, wet or dry, the warm-up/dry out hypothesis did not fly. The time interval was also the same whether the car was moving or idling. The only thing that seems to fit those facts is the battery needing time to build charge to a level that would not trigger the ASR fault.

I am not yet convinced I am out of the woods. I will reserve judgment until tomorrow, when we dry out and have another big change in humidity; and until next week or the week after, when we have the first very big variation in overnight temperatures. But for right now, this is very encouraging.

__________________
2008 E350 4matic / Black/Anthracite

------------------------------------
Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black

< >>

Don't see how that could be at all possible.

ECL switch S41 grounds the neg side of the lamp from A1 cluster module and that would have to have Key ON to power the cluster and if it were grounded, the indicator lamp would light, same as low coolant condition.

So, no circuit when car is off.
Check the schematic under Cluster Section/124

__________________
A Dalton