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Need some help to save a high-mileage (313K) but reliable 2002 E320 from the salvage yard! :cry:

Before I messed up my car, it was running great. (The only issue is the soft rattle of the hydraulic lifters, but everything else is fine.) Unfortunately, I used too much water while washing the carpets :oops:, and I didn't wait for the carpet to dry out before taking it out on a drive.

Within 2 hours, the following symptoms developed:
  • alarm started triggering on its own
  • car doors wouldn't lock with the remote
  • rear trunk started popping open on its own
The next morning before my commute, I observed additional symptoms:
  • none of the door window controls worked
  • none of the front seat controls worked
  • none of the turn signals worked
  • the overhead controls for the interior lights no longer worked
  • moon roof controls stopped working
  • SOS calls were being attempted
I took the car to an independent mechanic a few days later, and he recommended I junk the car:
  • the SAM would need to be replaced
  • the repair cost would be more than the car is worth
Of course, that was really sad news, as I had been planning to keep the car at least another 2-3 years. (Such an ignominious end for such a nice car! :mad:)

I left the car with the mechanic for several weeks, while I tried to see about getting a low-cost replacement for the SAM on my own.

Eventually, I had the card towed back home. In the meantime, the carpets eventually tried out in the summer heat, and miraculously, most of the symptoms went away:
  • car doors lock & unlock with the remote
  • all door window controls work
  • the front seat controls work
  • turn signals work
However, the car is still not entirely ok:
  • door interior lights stay on
  • the overhead controls for the interior lights don't work
  • moon roof still not working
Any ideas on how I should proceed? Unfortunately, I don't have much in the way of tools to diagnose electrical problems, other than a multi-meter and an oscilloscope.

I'm hoping to find out if there's a way to verify that replacing the SAM will fix the issues I'm seeing. I'd hate to replace the SAM (around $400 from the dealer) only to find out it didn't fix the problem.

Thanks in advance for any help.
 

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Hello:)

I do not believe the SAM is your problem. It looks like a signaling issue between the PSE and SAM and the door control modules (in case of door lights). Tackle one problem at a time, start with the door lights.

I would start disconnecting the battery negative terminal for 30 minutes and reconnect (with key out of ignition), and then check the functions above. Make sure you know how to re-synch the seats, windows, sunroof (if works), and you have the radio code available prior to battery disconnect.

If the problems still persist, you need to remove the carpeting in the passenger footwell (just in front of the passenger seat near the door sill). There, you will see a terminal block that handles signaling between body control modules. The reason why you had all these problems with the carpets wash is that this terminal block got wet and caused signaling issues between modules. With bad signaling, the SAM will disable modules that it cannot talk with, with the carpet dried, you got some signaling back. After removing the portion of the carpet, and exposing the terminal, dry it out completely with warm dry air. You may need to remove individual connectors to the block and re-connect to ensure proper connection.

It may be a problem with one of the door switches that signal the door is open even it is closed. In that case, if the signaling is intact, you will get the door lights turning off after some timeout, with the key out-of-ignition.
 

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Discussion Starter #3
Hello:) I do not believe the SAM is your problem. It looks like a signaling issue between the PSE and SAM and the door control modules (in case of door lights). Tackle one problem at a time, start with the door lights. I would start disconnecting the battery negative terminal for 30 minutes and reconnect (with key out of ignition), and then check the functions above. Make sure you know how to re-synch the seats, windows, sunroof (if works), and you have the radio code available prior to battery disconnect. If the problems still persist, you need to remove the carpeting in the passenger footwell (just in front of the passenger seat near the door sill).
I disconnected the negative terminal on the battery for 1hr, then reconnected. The same symptoms re-appear after reconnecting the battery.

There, you will see a terminal block that handles signaling between body control modules. The reason why you had all these problems with the carpets wash is that this terminal block got wet and caused signaling issues between modules. With bad signaling, the SAM will disable modules that it cannot talk with, with the carpet dried, you got some signaling back. After removing the portion of the carpet, and exposing the terminal, dry it out completely with warm dry air.
I found the terminal block. It has ten wire pairs connected to it, with an empty connector present. I've air-dried the block for several days now, and again, the same symptoms persist.

You may need to remove individual connectors to the block and re-connect to ensure proper connection. It may be a problem with one of the door switches that signal the door is open even it is closed. In that case, if the signaling is intact, you will get the door lights turning off after some timeout, with the key out-of-ignition.
I will try to disconnect then reconnect the ten wire pairs connected to the terminal block to see if that changes anything.

By the way, I also disconnected the 5uF capacitor connected on the two ground cables behind the aluminum floor plate on the passenger side. I examined its terminals, and found very slight discoloration (not sure if it was actual corrosion or not.) I cleaned up the terminals with a metal file, tested the capacitor using a multi-meter, and reinstalled. Again, no change in symptoms.
 

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I disconnected the negative terminal on the battery for 1hr, then reconnected. The same symptoms re-appear after reconnecting the battery.


I found the terminal block. It has ten wire pairs connected to it, with an empty connector present. I've air-dried the block for several days now, and again, the same symptoms persist.


I will try to disconnect then reconnect the ten wire pairs connected to the terminal block to see if that changes anything.

By the way, I also disconnected the 5uF capacitor connected on the two ground cables behind the aluminum floor plate on the passenger side. I examined its terminals, and found very slight discoloration (not sure if it was actual corrosion or not.) I cleaned up the terminals with a metal file, tested the capacitor using a multi-meter, and reinstalled. Again, no change in symptoms.
If you're cleaning up any moisture from electrical connectors, you should be using a product like CRC electrical cleaner to remove all the moisture.
 

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You need to take the connectors out (one-by-one) without losing the order they are connected. clean the connectors (both the cable and the terminal block with electronic contact cleaner. Let it dry, and re-install. Especially pay attention to the connectors #3 (rooftop module) and #10 (the last in the strip) for the PSE.

Have a look at the attached document. The door entrance lights are turned on / off by the PSE over a command to the door control modules (DCM). The rear dome light is also controlled by the PSE over a signal from the Roof Control Unit (N70). I have a feeling that the rear window defroster is not working.
 

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Discussion Starter #6
You need to take the connectors out (one-by-one) without losing the order they are connected. clean the connectors (both the cable and the terminal block with electronic contact cleaner. Let it dry, and re-install. Especially pay attention to the connectors #3 (rooftop module) and #10 (the last in the strip) for the PSE.

Have a look at the attached document. The door entrance lights are turned on / off by the PSE over a command to the door control modules (DCM). The rear dome light is also controlled by the PSE over a signal from the Roof Control Unit (N70). I have a feeling that the rear window defroster is not working.
I pulled each connector separately, and found that none of the connectors (both on the plugs and the terminal-block sockets) show any visible signs of corrosion or water intrusion. Nevertheless, I sprayed the plugs and sockets with electrical contact cleaner, keeping the original order when reconnecting the plugs into the terminal block.

Unfortunately, no change in symptoms, the rooftop controls still don't work.

I failed to mention in my original post that the red LED on the trunk (boot) switch stays lit continually. The trunk switch also does not respond.
 

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Check the PSE module under the rear seat where the battery is for water intrusion in the PSE model's base. Check the fuses in the same vicinity especially fuses 5, 7, 19, and 3.
 
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