1996 S420 EPC, ASR & Gas Guage Lights On

[EuroCoupe]

Hello All-
We have a 1996 S420 (W140) in the garage with the EPC (Electronic Power Control) & ASR lights on. The low fuel light is also flashing even though there is plenty of fuel. The car is in a limp mode and displays ocassional misfiring and will not exceed 30mph. I'm told by BlueLink that this is a "bastard car" that has an odd wiring setup and is different from most S420s in 1996. Supposedly there was a run of 2000 or so cars that had a wiring setup that is not found on the common diagram for that year. This is a 10/05 production car. Anyway, the CAN line is having trouble and the main computer seems to be "unlocked," meaning not coded to the car. We can take the ECU out and start and run another car fine, but cannot do vice versa because the drive authorization on another car's computer is still coded to that car and will not run this car (like it's supposed to). Wiring checks have shown nothing so far. Any ideas?

[mbdoc]

Most likely codes in the traction system(ASR) have caused the trans (EPC) to go into limp. Finding those codes & repair should allow the car to function again.

Flashing low fuel lamp is related to gas tank/cap integrity. Telling you to check cap.

[EuroCoupe]

Codes are for CAN communication errors. Checked the cap long ago. What's strange is that they will all go off sometimes, then back on, but always as a group- including the gas light flashing. The CAN line error would be fine for us to trace, but we can't trace the CAN line with the wiring diagram on WIS because its the wrong diagram for this car. We're checking grounds and solder points now as we've seen factory error with some soldering jobs too. Some kind of ground or short problem possibly, just really frustrating!

[ainlehen]

Originally Posted by EuroCoupe

Codes are for CAN communication errors. Checked the cap long ago. What's strange is that they will all go off sometimes, then back on, but always as a group- including the gas light flashing. The CAN line error would be fine for us to trace, but we can't trace the CAN line with the wiring diagram on WIS because its the wrong diagram for this car. We're checking grounds and solder points now as we've seen factory error with some soldering jobs too. Some kind of ground or short problem possibly, just really frustrating!

DEAR EUROCOUPE
I DO HOPE FINDING YOUR POST CAN BE THE ANSWER TO ALL MY PRAYERS !!!
PLEASE HELP !!
My 1996 S500 VIN: WDBGA51E4TA293613 shipped from DB factory on
October 9 1995 does have the same problem.
While (still) humming along fine in flowing traffic at highway speeds --
As soon as I get into stop/go city traffic -- All three lights will come on
and the transmission starts to shift very hard and irregularly !!
There is NO loss of power and acceleration so I do not know if this
can be properly called limp-mode !?
AS I AM SURE YOU FINALLY FOUND THE PROBLEM --
PLEASE HELP !!!
( I have already changed the EPC and ASR modules,checked harness etc.
and am at the end of my wits -- Can Bus indicating communication failure )
THANK YOU THANK YOU THANK YOU !!!!!!!!!!!!!!!!!!!!!!!!!

ANY HELP DEEPLY APPRECIATED !!!

SINCERELY
ANTON

[140Obsession]

Hi, I'm having a similar issue. How did you solve yours?

97 S420 - Confusing [possibly] CANBUS issue

[ainlehen]

Hi

Still hoping for help/solution myself

[140Obsession]

It looks like you have a donor car with all the same computers.
Have you tried switching them all over from one to the other? If they all work in the other car, you know it must be a cabling fault in yours

[ainlehen]

Problem solved !!
A ****ed up ignition coil ( Chinese aftermarket )
some weirdo mechanic had put in the car -- did
fire back into / screwed up the can-bus.