1994 420E Codes Results - PeachParts Mercedes-Benz Forum

pesuazo · #1 12-06-2008, 07:51 PM

Socket 19: 6 and 12
Socket 4 : 22
Socket 6 : 13, 30
Socket 7 : 5, 6, 14
Socket 8 : 5
Socket 30: 2, 4, 8
Socket 17: 1

I read many posts, and it appears some of the solutions to the codes were replacements of the Stop Lamp switch (S9/1) and the Starter lock-out/backup lamp switch, AKA Neutral Safety Switch (S16/1-3).

JimF's website provides a wealth of helpful information.

Harness will be rebuilt/replaced in the next couple of months.

What other solutions/troubleshooting techniques have been tried to solve the codes above?

deanyel · #2 12-06-2008, 08:59 PM

I don't believe there is such a thing as a 420E, probably an E420. Not everyone has memorized all the code number descriptions for all the models. It's always a good idea to put the code description in your post, not just the number. You should get a better response.

pesuazo · #3 12-07-2008, 12:12 PM

Diagnostic Module (N59) Socket 19:
6 - Idle speed control inoperative
12 - Heated oxygen sensor heater, open/short circuit

LH-SFI Module (N3/1) Socket 4 :
22 - O2S 1 heater, open/short circuit

ABS w/ASR Control module (N30/1) Socket 6 :
13 - Stop Lamp switch (ASD/ASR)
30 - CAN data line to EA/CC/ISC module (N4/1)

EA/CC/ISC Module (N4/1) Socket 7 :
5 - Stop Lamp switch (S9/1)
6 - Starter lock-out/backup lamp switch (S16/3)
14 - Closed throttle position contact switch (S29/3)

Base Module (N16/1) Socket 8 :
5 - Maximum allowable temperature in module box (F23) exceeded

SRS Control module (N2/2) Socket 30:
2 - SRS control module (N2/2)
4 - Front passenger airbag squib (R12/8)
8 - Voltage supply

Ignition Control Module (N1/3) Socket 17:
1 - No Faults in System

I need to find out if there is a systematic procedure to troubleshoot, given the codes shown above.

Thanks

JimF · #4 12-07-2008, 12:20 PM

Looks like you have an "ASR" and some other problems.

If you haven't reset the codes, do that and then see what comes back.

It could be the ETA which is detailed in Menu#24. If you're lucky it could be fixed by a Stop Lamp Sw or NSS. As you read, i had both go bad but not together.

You probably need to replace the O2 sensor; Bosch rates them about 60K miles, so it could be time to replace it. But first do a reset and see what comes back.

PS: that assumes that you have replaced the wiring harness.

pesuazo · #5 12-07-2008, 05:40 PM

JimF,
First I want to thank you for your great website, the information there is great.

I have not replaced/rebuilt the harness, that is in my "to do" list.
A little background about the car:
I bought this car from the original owner for $1K (175K miles), it was parked under a foot of pine needles, the owner told me he parked it there 3 years ago and never moved it, he could not even remember if there was anything wrong with the car. He gave me the original window sticker ($54,375.00).
Long story short, I drove out (with a friend) to the outer banks (about 140 miles) with a dolly to tow it back to Raleigh, NC. Surprisingly (after an oil and filter change) the car fired right up (with my truck battery), and I drove it home.
It performed very well, I ran it up to 110 MPH, and it pulled like a freight train.
The check engine light came up when I parked it home.
I found out about the harness problem once I started searching for codes and how to pull them.
The original battery was dead (1.5 volts) after the 140 mile drive, which may be a reason for some of the codes (I also read in some posts that low voltage could cause some codes).
The alternator is OK, as it puts out 13.5 - 14 VDC. The car ran all the way home with alternator power alone (old battery installed), which explained some of the apparent electrical gremlins when I started testing all the "luxuries" during the drive (cruise control, heated seats, rear curtain, CD changer, etc...).
Under close inspection, I could see the bare wires around the temp. sensor.
By the way, I detailed the interior, and it looks brand new.
I will see if I can post some pictures.

JimF · #6 12-07-2008, 07:39 PM

Tnx for the run-down on the car . . . makes it much easier to give you some suggestions.

Reset the codes, after replaceing the battery . . .

Your FIRST job is to replace the wiring harness and then the O2 sensor and you might be good to go!

If the ETA is bad, you will get the #6 code and the same codes shown in MENU#24 but with the car sitting that long, it may be just "inactivity".

Larry Delor · #7 02-06-2009, 12:35 AM

The O2 sensor is in a lousy place. Plan on lifting the car up, so that you can drop the exhaust a little, in order to get to the sensor.

It is at an angle, towards the top of the Y.

I think, I remember someone telling me that the throttle position contact switch is inside of the ETA. Many ETA's suffer(ed) from substandard wiring insulation as well.

Will_w202 · #8 02-06-2009, 06:44 PM

Check PM

If the harness is now good, then the ETA is probably the next culprit. You can try replacing the cheaper stuff first, but ETAs are known failure points. The o2 sensor will strip before you can get it off, unless you use alternating heat and cold (torch and cold water). Use a mirror, mark it and make sure you are getting movement else you will need the special tool to dremel it out! Taillight assembly contacts get corroded, causing ASR lights and limp mode. You can swap them with used parts or repair the contacts. Don't forget the wheel speed sensors, which can cause gremlins as well.

pesuazo · #9 02-09-2009, 09:25 AM

[QUOTE=Will_w202;2102275]Check PM
The o2 sensor will strip before you can get it off, unless you use alternating heat and cold (torch and cold water). Use a mirror, mark it and make sure you are getting movement else you will need the special tool to dremel it out! QUOTE]

Right on the money!!!
Even though I have the O2 sensor remover socket, it still stripped!!!
I remember some one wrote that the O2 sensor location was picked by Satan, I could not help burst in laughter when I was trying to remove it.

It became:

Mission impossible!!

It will stay there until I can figure something out.

What is the special tool to dremel it out?

pesuazo · #10 04-03-2009, 02:34 PM

It has been about 2 months, so I decided to update.

I have had 3 LH modes in all this time (it happens, but about once every other week). A restart takes it away.

I still have the Check Engine Light, I know, the O2 sensor (still cannot get it out, will give it another shot this weekend).

These are the codes I am getting after 2K miles.

LH-SFI Module (N3/1) Socket 4:
22 - O2S 1 heater, open/short circuit

ABS w/ASR Control module (N30/1) Socket 6:
30 - CAN data line to EA/CC/ISC module (N4/1)

EA/CC/ISC Module (N4/1) Socket 7:
6 - Starter lock-out/backup lamp switch (S16/3)

14 - Closed throttle position contact switch (S29/3)

Base Module (N16/1) Socket 8:
10 - Base module (N16/1) voltage supply output fuse F2 open circuit
11 - Base module (N16/1) voltage supply output fuse F3 open circuit
12 - Base module (N16/1) voltage supply output fuse F1 open circuit
13 - Base module (N16/1) voltage supply output fuse F4 open circuit

Ignition Control Module (N1/3) Socket 17:
1 - No Faults in System

Diagnostic Module (N59) Socket 19:
6 - Idle speed control inoperative

12 - Heated oxygen sensor heater, open/short circuit

SRS Control module (N2/2) Socket 30:
9 - SRS warning lamp (A1e15) or insufficient time to read out the DTC memory or erase DTCs

Somewhat different from the last time. I replaced the brake line and the brake light switch.

Socket 8 codes are BS, as all the fuses are OK.

I will erase all codes and drive for a week to see what comes back. I know for sure the O2 will be back (22 on socket 4 and 12 on 19)

The only thing to replace is the NSS, but I will not do it unless LH becomes a REAL problem (more than once a day).

david s poole · #11 04-03-2009, 03:00 PM

i think you can get rid of a lot of those codes by replacing the electronic accel with a rebuilt.the wiring in the pigtail connector will be toast as well as the internal wiring.

GDC · #12 04-06-2009, 06:08 PM

Good job on rebuilding the harness. Did yo run new wire all the way to the computer connector or did you splic in near the battery? If you spliced in you want to keep an eye on the remaining old wiring as you may get a short inside the connector (ask me how I know)

You can try rewiring the ETA. I did and got another 6 months before the internal pots died and I had to buy a replacement. If you want a recommendation for a source for a rebuilt ETA pm me.

Greg

pesuazo · #13 04-07-2009, 11:01 AM

Quote:

Originally Posted by GDC

Good job on rebuilding the harness. Did yo run new wire all the way to the computer connector or did you splic in near the battery? If you spliced in you want to keep an eye on the remaining old wiring as you may get a short inside the connector (ask me how I know)

You can try rewiring the ETA. I did and got another 6 months before the internal pots died and I had to buy a replacement. If you want a recommendation for a source for a rebuilt ETA pm me.

Greg

I did splices behind the firewall (about 6 inches from the connector). The wire insulation was good and soft at that point. The battery for the E420 is in the trunk.

I will PM you for the info, although I live relatively close to Beckman technologies in Durham.

JimF, indeed it requires practice, got to release the gas pedal just enough to shift, and then feather the gas to keep the speed without downshifting.

GDC · #14 04-07-2009, 01:18 PM

I did the harness on a 1993 300E with the battery in the engine bay. My wiring looked good from the computer connection to just after it exited the battery compartment.

A few months after rewiring, I developed a misfire that the codes kept telling me was a bad coil pack even though all three were brand new. I finally found the problem by ringing out the primary side of the the coils and finding that cyl 2 was shorted. The short was actually inside the epoxy potting compound inside the connector housing.

The good news is that the plastic housing is available from MB for under $20.00. the bad news is that the only way to get the 44 pin connector plate is to buy a new harness. I wound up cutting the old housing off and rebuilding the harness a second time from the computer connector to each termination. Surprisingly all of the coaxial wires had a silicone insulation that showed absolutely no degradation, so I was able to simply slip them through the new connector housing and resolder them in their original location.

Greg

pesuazo · #15 07-02-2009, 12:12 PM

Just a last update, given the car has been on the road for a while.

Found the root cause of the occasional ASR with Limp Mode. It was not the NSS or ETA.

The rear passenger side tire loses air slowly, I had not made the connection until yesterday.

Limp Mode would not go away with a restart. Checked tire pressures and it was 25 psi, the other was 35psi. Filled it up and ASR went away.

Drained the air down to 25 psi, ASR with limp mode came back right on take off, filled tire up, it went away.

I did it 3-4 times to make sure (repeatability). Another lesson learned.

By the way, got a new AC compressor from Duracool, after doing the necessary steps (vacuumm, check pressures, etc..). Vent temps are 39.1 - 41.2 on the highway on a 94 degree day with 60% humidity. Can't complain.

Also changed the water pump while I was there (do not ask me what it took to remove the harmonic balancer, I rather forget - PITA)

Additionally, installed the "cool harness" (soldered a 1150 ohms, 1% metal film resistor). Fans come on like clock work around 94-95, and shut off at 87. Thanks JimF, I am a regular visitor of your website (always looking for updates)

I will bring the car to a shop to replace the O2 sensor, I just cannot do it.
That will get rid of the check engine light and the codes (22 on pin 4 and 12 on pin 19).