I am having trouble figuring out my CAN B troubles and would love some input! Here is what I know.

I tested every fuse in the car and found that they are all good.

With the battery disconnected I measured the CAN B bus resistance between CAN low and CAN high I am getting about 10,000 ohms and not the 60 ohms for two good resistors or 120 ohms for one good resistor. I am measuring at the connector where all the modules plugin located by the passenger A pillar.

The CAN low voltage is 4.8V asleep and 3.2V awake. The CAN high voltage is about 100 millivolts asleep and awake.

Given the reading I have done I am figuring that the body control module is bad. Is it located in the electronics box located on the passenger side, the most forward one in the box?

Where are the two 120 ohm resistors located?

Am I measuring the CAN resistance incorrectly? It seems wrong to me that both resistors are both electrically open.

The things that do not work are the power windows and sunroof primarily. Power seats and interior lighting do work.

I welcome any help that you can provide!!!!

__________________
____________________
1984 300CD (sold)
1973 220DPK 4 spd (died)
1978 350SL 4 spd gray market
2003 SLK32 AMG
1988 300CE (sold)
1997 E420 (Totaled)
1998 E320 Wagon

jaybutter, our 1998 E320 has had electrical gremlins for years. With the engine running pull Fuse 16 (20 amp) from the fuse box in front of the brake booster. Remove it for 30 seconds or so, then reinstall and try operating the power windows. I need to perform that exercise every week or so, when the driver's seat will not move. Our local MB dealer's service department has no idea what causes this problem, or how to fix it. Go figure.

__________________
Fred Hoelzle

I have worked thru this and have found the following.

1. The SAM (Signal Acquisition Module) had a faulty CAN Bus host. The CAN high was not functioning. I got very lucky in that the local PNP had a 2001 wagon that had a good and correct SAM in it for $20.00.

2. The power window switch module was also bad but again the PNP wagon had a good unit for $15.00.

3. On the good SAM, with the battery disconnected the CAN high to CAN low resistance is 180 ohms. There is no other resistor with all the control modules connected in a star configuration on the passenger A pillar terminal strip.

Ferdman, thanks for your input! I'm glad that you have a work around. It did not work in my case primarily due to my bad SAM!

__________________
____________________
1984 300CD (sold)
1973 220DPK 4 spd (died)
1978 350SL 4 spd gray market
2003 SLK32 AMG
1988 300CE (sold)
1997 E420 (Totaled)
1998 E320 Wagon

jay let me know if you ever see a 98/99 E300 in the yard.

__________________
Jim