It appears you are correct, DAS is apparently stand-alone in the 1998 W140. Got a call from my cousin last night, he found the STAR wiring diagrams on the laptop and located the source power fuse for the DAS module. It was either blown or had a mechanical failure and was not supplying power and he reports the car is now fixed. I'm sure he'll chime in when he gets the time and fill us in on the details.

Discovered that I had missed a fuse in the underhood fusebox that had a
hairline crack. Fuse 18 and fuse 20 feed the DAS and the A/C system, fuse
20 was not conducting. Popped in a new (new new, not a new, used) fuse and
the car started with all the original modules still in place.

The original problem was a catastrophic loss of coolant that we eventually
traced to a corroded metal heater pipe that ran from the solenoid valves
through the forward firewall then to the heater core. There were rubber
hoses between the heater core and the pipes, and between the pipes and the
solenoid valves. The solution was to open a new hole in the forward
firewall, then bypass both pipes and connect the solenoid valves with the
heater core using a pair of rubber heater hoses.

During discovery, we disassembled the cowl area below the windshield,
including the fresh air plenum, the wiper system, and the fresh air
filter. Running along the top of the forward firewall is a channel with a
wiring harness in it that appears to go to the electronic boards near the
rh hood hinge.

I'm suspicious that there may be a wiring fault, since the problem seems to
follow disturbing the wiring and the channel, and the fuse blew a second
time whilst reinstalling the parts.


I replaced the fuse a second time and the car restarted, and continued to
run.

Need to check current draw on that fuse, and see if there is a short that
is blowing the fuse. If no issue, then I'll perturb the wiring harness and
see if I can get the fuse to blow.

Ah well, at least it starts now.

I've also got story about towing the parts S500 home on Friday from
Richmond to Tidewater, but it's a long story, and I'm tired....... I'll
just say that credit must be given to the St. Christopher medal I've worn
around my neck since I was diagnosed with cancer (was my grandmother's).


Jim

129 820 37 26 any idea where is find this?
 

129 820 37 26 any idea where is find this?

Did you actually search? They seem to be all over the place.

Find Mercedes W140 ,R129 SIEMENS sensor, 129 820 37 26, 5wk4 680 motorcycle in Rocklin, California, US, for US $95.00