ASR light / limp home / fault code 6
 

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.

It sure sounds like it's . . . .
 

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.

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.)

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.

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

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

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

Thanks, I will do that.

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.

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.

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...

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.

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

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

Could said wet connector have caused an undue battery drain before the car was shut down, with the load from the other always-on systems, i.e. alarm, clock, etc., accounting for further drain, which normally would have no impact?

I just find it odd, and no coincidence, that the ASR issue has not occurred since that sensor was replaced.

As an aside, two years ago, in one brief, freak incident, my ABS pump kept running after the car was shut down. I don’t see how it could have occurred with the car off/no circuit, but it did, which made me wonder whether to same thing could have occurred on the other side of the engine, with the coolant sensor plug.

There's a 'easy' test that anybody can do to 'check' your battery condition.

It's so simple esp if you have your car garaged. When you go to start it, hesitate a second before engaging the starter to observe the IC lamps. That's your reference level.

Now start the car . . don't take your eyes off the IC; if the lamps dim . . .you've got a battery problem . . . and that will cause phantom problems. You should see almost no decrease in lamp brightness if the battey is "ok".

As I wrote in MENU#33, I recently observed my IC lamps dim badly and sure enough, the battery was 'weak. Details in the article.

<< in one brief, freak incident, my ABS pump kept running after the car was shut down. I don’t see how it could have occurred with the car off/no circuit, but it did, which made me wonder whether to same thing could have occurred on the other side of the engine, with the coolant sensor plug.
>>

No Mystery on that one...the ABS relay contactor was stuck closed and the relay secondary side needs NO KEY b/c those contacts [ 30/87] are ALWAYS HOT, regardless of key position ..it is the relay circuits primary/coil side [85/86] that is KEY cycled....NOT the contactor side.

But on your CLS -S41 circuit, I don't care if you screw the sensor wire to the engine for a ground, it will not be energized until the power is switched/ powered on by KEY/POSITIVE side ...this is according to your schematic, of course......the S41 sensor is a SWITCHED GROUND, completeing the Cluster Indicator lamp...nothing else/more..

JimF:

The IC lights remain steady and bright. (That's a great test, by the way.)


Arthur:

So, is it somehow possible the battery drain was occurring before the car was shut off? (I know it sounds odd, after all, how much power could possibly be drained from a grounded coolant sensor plug?)

Or is there some other component or wiring near/beneath that plug which, if wet, could cause a drain or otherwise trigger an ASR fault? (I vaguely recall someone writing in another ASR thread about a coolant/water leak connection to his problem.)

Edit: If there is such a component, it appears hypersensitive to moisture, considering that humidity changes will impact it.

You may have an ASR circuit connection/component that is sensitive to humid/heat/or other conditions...that is quite common on automotive connections due to the enviorment. But the thought that the S41 sensor electrical circuit has anything to do with ASR circuitry is without any logic.
If the sensor for CL is grounding, the only thing that is in that circuit is the Indicator lamp. And a grounded S41 would result in the indicator being lit if that were the condition. And even then, the draw would certainly not be sufficient to result in a Low Voltage fault to trigger an ASR fault. I do not see a connection between the two independent circuits in any way.

Water leak from sensor getting to an ABS/ASR component ??? I doubt it, but look around that area if you feel that to be possible.
I side with Coincidence ...........

You may want to check all the Brown Ground wire connections under the hood...[ there are several and a simple tightening is all,that is required]...they are commonly sensitive to humid conditions, as are ignition components.

That much I know. I was speculating on the possible connection between the leak and a battery drain, and the low voltage leading to an ASR fault, as MB Doc described. (I realize the ASR circuitry is in no way connected to the coolant sensor.)

Maybe it is coincidence and can be chalked up to one of those enigmatic things about this car. But it is equally without logic for a fault that was 100%consistent and predictable for the last 7 to 8 moths to suddenly correct itself -- not that I am complaining. :)

I change my oil tomorrow and will take a look at any wiring in that immediate area, since it is so close to the battery.

Thanks for the good feedback.

< But it is equally without logic for a fault that was 100%consistent and predictable for the last 7 to 8 moths to suddenly correct itself -->

Not at all...Electrical connection do that all the time and is logical. Do not be surprized to see it return.
If I were to suspect a low voltage condition on an124.032 HFM car, my first suspects would be the OVP and/or Voltage regulator, followed up by fuse holder end connections and chassis ground connections............. in that order..........
If it were the V8 versions, I would skip the OVP b/c they do not use one.

I've been holding my breath for the past three weeks over that thought. Today, given the hurricane weather, it absolutely should have, but I'll just be happy that it didn't.

It's not a big deal , so don't worry about it til it does , if it does..
Intermittants and glitches are very difficult and you may never find the original cause.
If it were me, I would build that led tool and go into the HFM and EA modules every once in a while and see what pops up before any ASR or CE lamp notification..You may just catch it before it clears itself again.
Pending codes are accessible w/tool before they trigger a lamp and the diagnostic modules are fast enough to catch them...but you have to catch them before they clear themselves b/c they do not repeat...
Pin 8 and 14.

Funny; I have had the schematic for the "Dalton 1000" (my name for the tool after the incident some years back when someone here was selling it on Ebay) in my "My Documents" folder for years, and never built. Perhaps now I will.

Yeah..one of the Kids here took it a step further and sold the idea on ebay ...I made several and sent them out to members for free, but when they started marketing them for sale , I let it go ...you can build it pretty easy for a couple of bucks and it is a cool tool for the DIYer.
The tool advantage is you can get to the Main modules ..whereas the built-in one only gets you Emmissions related codes that activate the CE lamp. ...not much help on the intricate systems, such as ASR, etc....

Just thought of another thing:

I replaced the coolant sensor the day before my annual vehicle inspection, during which the passenger-side front and rear wheels were removed.

I have not removed the rear wheels since changing the tires more than a year ago. Perhaps a dirty wheel speed sensor was inadvertently cleaned when that happened(?)

(as an aside, ny rear pads are starting to wear (front pads are new), and the brake light had been constantly illuminating strongly. Post inspection, the brake light now only illuminates once in a while, and in brief flashes.)

Maybe the connection is with the wheel speed sensor...

Possible..

Another possible is you put air in the tires when you were doing this work...a common ASR code fault is triggered by unequal tire pressure. That shows up on the ECU as it compares all four wheel speed sensor inputs by tire DIAMETER...now , that is LOGICAL......:)

May even changed the front to rear when putting tires back on......

Didn;t add any air, and though I observed the inspector/tech remove the wheels, I never noted the replacement order, but will check that tomorrow -- which will be easy enough since I (should) have same-size ContiTourings in back, and ContiPros up front, however, the ContiPros are newer.

Some Techs claim that even a 1/4" D difference can cause ASR code problems... which is why equal AP is so important...it is the rolling circumference that is the factor to be concerned with for proper WSS inputs..and AP has a direct relation to R/Circ.....
Worth checking into........

I definitely will.

Also, I replaced the front brake pads myself about 4 days before the inspection, and did use brake parts cleaner. Although it's possible I inadvertently cleaned a speed sensor, I will focus more on tire diameter.

I misread your post. I just turned the key and looked at the lights without starting. :o When starting, my lights definitely dim.

For me, this is distilling down into a voltage issue. Whether it is an Over or Under voltage is unclear, but arrows point to the voltage regulator and/or battery.

My car was parked for 2.5 days this weekend; conditions were very humid with heavy rain on Sunday. Sunday night I correctly assumed the ASR issue would return, so I drove the car and made these observations:

ASR fault appears to be triggered by a change in voltage, whether from A.) An electrical load being applied, i.e. the brake lights; or B.) A diminution of voltage/current from the alternator, i.e. foot off the accelerator, and engine/alternator revs dropping below an approx 550rpm threshold, and concurrent drop in voltage/current.

ASR illumination is accompanied by the click/ping of a relay (OVP?), audible in the center dash blower area (but on one occasion it sounded like it was coming from behind me).

The fault took MUCH longer to clear this time and I initially thought, “It finally failed for good.” But then the Common Sense Fairy pointed out, “This is your first drive in over 2 days, it is the first time you are expereincing it at night so your head & tail lights are on, you have the blower motor running, and are drawing a large electrical load – not optimal conditions for trickle charging a battery -- assuming low battery voltage is the cause.”

When the condition finally cleared, after about 30 minutes of driving (compared to the typical 1-5 min), I felt the urge to hear some music and turned on the CD player. Approaching a red light, I applied the brakes, adding electric load, and click/ping went the relay and on came the ASR. Turned off radio, drove a bit further, restarted, and the fault cleared as usual.

Evidence suggests weak battery and/or worn voltage regulator. I don’t know how the stop light switch circuitry works, beyond illuminating the stoplights, so I won’t rule it out as a cause either.

If the battery appears 'weak' (which the IC light test seems to confirmed), test it using a load tester.

But it does sound like you have a going-bad ETA. If you read my scenario (Menu#24) when mine started to go, the same events happened.

If your car "sits" for a few days, that shouldn't cause the ETA to be 'marginal' but the battery is further stressed esp since it appears to be weak.

Jim, thanks.

I actually read and bookmarked your #24 as a "bible" when the problem first appeared last Fall. :)

The key variances with my car are that the ASR occurs only under (apparently) weak battery conditions, i.e., first start of the day if the car has been sitting for more than 24 hours -- or 15-18 hours if it is very humid, or very cold -- and goes away for good once the enginne has been running for a short while. Also, as you pointed out in post 11, the fault has not gotten worse over time.

In the IC test, I also notice the lights dim more in the mornings than they do in the afternoons, when leaving work. Also, and this may or may not be relevant to this issue, the SRS light remains illuminated a second or two after the other lights dim. Last night, it stayed lit for about 3 seconds and, if memory serves, this is also an indicator of voltage/battery issues.

I will have a load test done, and check the voltage regulator for excess wear. My current battery is at least 4+ years old, so I will plan on replacing it and/or the regulator.

Eric,

Wondering how you solved your ASR issue. I just rewired mine last weekend because the harness was a bunch of crud. I had similar symptoms to yours but my ASR/Limp home eventually became permanent. I removed the ETA and under the non-control side cover found a mess of degraded wiring.

So far, I have done nothing, since there have been no issues.

However, what I wrote previously about voltage issues is only circumstantial. I now am convinced that my problem is related to the stop light switch.

After my last post, I did some experimenting. The issue has nothing to do with low voltage because, upon starting the car after sitting over another weekend, I turned on all lights, radio, etc. Nothing happened. If it were a voltage issue, as I originally conjectured, then the ASR would have tripped.

As long as I did not touch the brake pedal, the ASR fault was not triggered. If I idled the car for 1 to 10 minutes after startup (depending on temperature and humidity) I could drive away with no ASR issues. If I tapped the brake at any point before then, the ASR fault would appear shortly or immediately thereafter.

Not sure how it works, but the Stop Light Switch is involved in several functions, i.e. cruise control, ABS, ASR, etc., in which the ETA is also involved. So the likelihood of miscommunication is great.

On two or three occasions, on the first drive of the day, I have also heard a short, low buzz when applying the brake, very similar, if not the same, as the buzz you hear when you leave the key in the ignition – or when you blow the fuse that controls the instrument cluster gauges. I have never read any documentation on this, but that buzz might be a faulty stop light switch warning.

We have cold weather returning tomorrow, and I will observe the behavior once more, before going ahead and ordering the replacement switch (as I should have done months ago).

Following up on my previous post, behavior after idle continues as described. I am now also suspecting the coolant temperature sensor has a role is this.

It is the one component whose behavior/ non-behavior would consistently correlate to the temperature/humidity issues I have described throughout this thread. And I have noticed previously, and again in our current cold weather, that the ASR fault does not self-correct until coolant temp reaches 81/82. I will go out on a limb and say there must be a connection.

Measure the resistance . . about 300 ohms @ 100C. The failure mode is "increasing" resistance. So if it's 800 ohms, replace it.

Brilliant, will do.

In late August/Early September I had to replace my expansion tank cap and coolant level sensor at the same time because of deteriorated o-rings. If the ECT(?) sensor also has a similar rubber seal, I am certain it too has failed, and is the source of the problem. Will know for sure when I am under the hood this weekend.

Revisiting this issue:

While under the hood today I noticed powdery-white corrosion on the bolt-down plate that secures the battery, and some additional corrosion on the positive terminal. I removed battery, cleaned/scoured away all visible corrosion, and replaced it.

Upon starting the car it fired up very strongly and the tach, instead of surging a bit as it typically has been doing, remained locked in the 1000 rpm range. Upon driving off, the anticipated "first start of the day" ASR fault did not occur.

It’s too premature to say for sure the ASR problem was a voltage issue all along, but I’ll chime in again after a week or so if it does not return. Nonetheless, it probably is/was electrical, with the NSS playing a role.

7/27 Update:
Still no ASR faults. :D

I'm curious, do you think it was a voltage issue that was causing the problem? Has it returned since?