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  #16  
Old 01-12-2012, 11:10 AM
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Quote:
Originally Posted by 1992_400e View Post
Well, I was the one giving the gift. I can't expect my 66 year old mother to fix it herself. Hence my quest for some good advice on diagnostics.

It would be easier if it was my daily driver but as I have to almost wrestle her for the keys, my time to fix it is somewhat limited. (or I get stuck being her personal cab driver)
lol, I know, I was just givin you a hard time
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  #17  
Old 01-12-2012, 11:12 AM
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Quote:
Originally Posted by gerryvz View Post
This is absolutely incorrect. Wiring harnesses WERE an issue on 1992 model year V-8 cars (500E and 400E).

The 400E/E420 used Bosch LH injection, NOT HFM (which was used on the 6-cylinder M104 cars starting in model year 1993; 1992 M103 300Es used Bosch KE-Jet).

ETAs are a fairly common failure (due in large part to the same issues with their internal wiring as the upper wiring harnesses have) but again you need to do some things before you start throwing parts at the problem.

Don't bother changing out fuel filters until you do the following:

a) replace the wiring harness, particularly if you don't know for sure that it has been previously changed. That is a baseline that you MUST do.

b) Pull the codes using the home-made code reader as mentioned previously.

You may gain some benefit from the forum at ********* Galactic HQ as it shares the same engine, and there are a few 400E owners/experts on that forum (as well as a fairly new sub-forum that is specific to the 400E/E420).

Don't throw money and parts at the problem until you replace the upper harness, and pull the codes (in that order). The codes will point toward the real issues. The reason I say to replace the harness first is that it is tied into the proper operation of the engine; and a faulty harness has also been known to fry one or more of the car's computers. Not saying that it will happen, but it certainly has.

Cheers,
Gerry
Really! Learn something new every day. I've seen the opposite posted here several times. Why have I been told otherwise? And why does my 92SL not have the harness issues? What does the harness have to do with LH? Did they use a biodegradable harness on one assembly line and not on another? Interesting. I've always heard it was the 93-95 cars that had the issue.
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  #18  
Old 01-12-2012, 11:28 AM
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It depends on the model - not all 1992s had the issue as this year was when MB was phasing in changes across numerous model lines, switching from M103 to M104 engines in the w124 sedans and wagons, and so forth. But very definitely 1992 model year V-8 cars using LH injection had the harness issues. I don't believe that KE-Jetronic injection V-8 or inline-6 based cars (which your 1992 500SL would have been, if I remember correctly) had the harness problems. I had a fairly late-production 1992 300TE wagon (M103, KE-Jet) and it didn't have the problem.
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  #19  
Old 01-12-2012, 03:57 PM
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Quote:
Originally Posted by Will_w202 View Post
Really! Learn something new every day. I've seen the opposite posted here several times. Why have I been told otherwise? And why does my 92SL not have the harness issues? What does the harness have to do with LH? Did they use a biodegradable harness on one assembly line and not on another? Interesting. I've always heard it was the 93-95 cars that had the issue.
You really missed it on both ends - there's compelling evidence that the problem went into 1996 on the HFMs. The internet can be a great tool for repeating misinformation.
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  #20  
Old 01-22-2012, 06:17 PM
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So, finally pried the 400e away from my mother for a few days.
Just popped the hood and checked the tag on the harness (right at the passenger side firewall)

I'm confused by the PN tag. All the photos I've seen have "delphi" on them.
My tag only has PN A1245138832 on it. No date of manufacture or any other identifying marks.

Anyone have an idea if this is an original wiring harness or if it's a replacement?

Thanks,
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  #21  
Old 01-22-2012, 06:58 PM
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Very likely it's the original then. As I said, carefully split an inch or two of the outer sheath open with an X-acto knife and check the condition of the wiring inside. Do this near the engine, not near the firewall. You'll likely find your issue after you see the condition of the wiring inside.

Rule of thumb is that if you don't have documentation that a harness has been changed, 95% probability that it has never been changed. Be prepared to pay around $700 for a new factory harness (no aftermarket units made) from MB. Cheapest place to order is through XXXX.

Cheers,
Gerry
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  #22  
Old 01-22-2012, 07:39 PM
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Thanks Gerry,

That's pretty much what I figured, I've run out of light for the day and was hoping for some good news. Hoping, not expecting.


Cheers,
Ian


Quote:
Originally Posted by gerryvz View Post
Very likely it's the original then. As I said, carefully split an inch or two of the outer sheath open with an X-acto knife and check the condition of the wiring inside. Do this near the engine, not near the firewall. You'll likely find your issue after you see the condition of the wiring inside.

Rule of thumb is that if you don't have documentation that a harness has been changed, 95% probability that it has never been changed. Be prepared to pay around $700 for a new factory harness (no aftermarket units made) from MB. Cheapest place to order is through XXXX.

Cheers,
Gerry
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  #23  
Old 01-24-2012, 12:18 AM
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Update:

I cut the wiring harness open right by the valve cover.
It looks pristine inside. The wires are even flexible. It does look a bit newer than the other components (rubber cover is very supple) so I'm guessing it's a replacement.

I also cut the harness to the Electronic Throttle Actuator open and the wires there also look fine.

Since I've still got the intermittent stalling and idle hunting issue I suppose the next step is cleaning the MAF, the throttle body and running the codes.

Thanks again for the help.
Ian
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  #24  
Old 05-09-2013, 01:00 AM
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Another update on this.

I ended up replacing the MAF, it helped a bit but the car would still hunt for the idle, die and occasionally go into limp mode.

It was too stressful for my mother to drive it, so I got her a new car and took the benz home with me. It was mostly driveable by paying close attention to the idle and sometimes riding the brake with the left foot while keeping a bit of gas on with the right.

The alternator and the belt tensioner both died on me, and after replacing the belt tensioner I've driven it a few times just by charging up the battery real good.

Now here's the punch line. Without the alternator working, the motor runs just sweet as can be. Idles perfect, starts perfect, etc. At least until the battery drains and then it start to run like crap.

Could my issues have been caused by a bad alternator? Is the computer really sensitive to variation in voltage?

I'll be replacing the alternator shortly so it will be interesting to see what happens then.

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  #25  
Old 05-18-2013, 10:25 PM
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Another update.

I finished replacing my alternator today and also replaced the wire from the 2nd terminal to the x4/10 junction box. Now I've got full voltage the way I should.

How does this relate to my idle issue? Well, I don't have an idle issue anymore. The idle is completely stable now. Also, no stalling. No stalling at all. Hot or Cold.

Before after a good drive it would almost always stall at a red light or stop sign.

So here is my theory:

1) The alternator has been going bad for awhile and throwing voltage spikes. These abnormal voltages were causing all the odd behavior.

or

2) The alternator had nothing to do with it. The change in idle behavior/stalling is only because it's summer now, and the problem is actually a bad temperature sensor.

Not sure which one is correct. I'll just keep driving and see if the issue comes back in the winter.

Any thoughts? Has anyone else had an idle/stall issue that was traced back to either a bad alternator/voltage regulator or to the temperature sensor?
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  #26  
Old 05-20-2013, 01:46 PM
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when you replaced the MAF did you get a $90 dolllar E-bay one or the bosch factory $300.00 dollar one. I made this mistake on my M119 and had all the same symptoms you did. I put in the good expensive MAF and the car runs great now! I learned my lesson.....................................................
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  #27  
Old 05-20-2013, 05:35 PM
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Quote:
Originally Posted by johnflight1 View Post
when you replaced the MAF did you get a $90 dolllar E-bay one or the bosch factory $300.00 dollar one. I made this mistake on my M119 and had all the same symptoms you did. I put in the good expensive MAF and the car runs great now! I learned my lesson.....................................................
I replaced with a Bosch unit. The car ran slightly better but it didn't cure the idle hunting or the stalling.

Those issues were not resolved until I replaced the Alternator.
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  #28  
Old 10-11-2013, 09:20 PM
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Any updates on resolving your idling issue?
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  #29  
Old 06-19-2014, 10:27 PM
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The idle issues continue. I started a business so the 400e has been parked for almost a year.

Last July it was running great. Took it on a road trip, averaged 9.3 Litres per 100k (25.9 US MPG) which included some... spirited driving.

Thought my troubles were behind me but shortly after that it began to have a hot start issue. Lots of limp mode, etc... anyway, after a long break I'm back to troubleshooting.

Finally got a code reader and this is what I pulled:
  • Socket 7 Code 3 Cruise control/idle speed control actuator
  • Socket 8 Code 5 Maximum permissible temperature in module box exceeded - Base Module
  • Socket 8 Code 8 Voltage supply for LH-SFI control module interrupted
  • Socket 16 Code 13 Engine coolant temperature sensor, open circuit

Questions:
  1. Is the Cruise Control actuator dual purpose? As in it controls the idle as well?
  2. This appears to be the part number 0025458632 but it's referred to only as the Cruise Control Servo.
  3. What does this mean? Is it melted? Base Module: Maximum permissible temperature in module box exceeded.
  4. Voltage supply for LH-SFI control module interrupted. Does this mean it's not getting power? (car isn't starting at the moment)

Thanks in advance.
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  #30  
Old 06-19-2014, 10:49 PM
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If you are going into limp home mode then your car has ASR, which means that the Electronic Throttle Actuator (ETA) controls three things: Cruise Control, Engine Acceleration and Idle Speed Control. Have you checked the date stamp on your ETA? The ETA's are also built with the same bad wiring insulation as the engine harnesses and tend to go bad over time. If it is original, it could very well have failed.



The max temp in module box is something that happens on most of these cars when it gets really hot. I think you are safe to ignore that code, like most of us do.


Have you checked the Delco 10A fuses in the module box?
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