ASD Triangular light not illuminated - PeachParts Mercedes-Benz Forum

stephenson · #1 01-03-2013, 08:05 AM

I started a post on this, but the issue and troubleshooting has expanded, so I am summarizing in this post with the hope of getting additional thoughts. The original post is at: ASD troubleshooting - partial success, and was getting assistance from 200t on another forum, and that post (in 124 forum but with som diagrams) is at: Must ASD Lamp light up? - Benzworld.org - Mercedes-Benz Discussion Forum.

Here is summary:
Failure indication 1
ASD LIGHT DOES NOT EXTINGUISH AFTER START UP
- traced to code for right front wheel sensor; removed, cleaned and reinstalled both front wheel sensors and the speed sensor on the top of the differential
Result - ASD malfunction light came on during start sequence, then extinguished ...normal operation restored

Failure indication 2
TRIANGULAR LIGHT DOES NOT ILLUMINATE ON START UP OR DURING WHEEL SLIPPAGE
- pulled dash cluster and checked bulb
- checked hydraulic fluid level
- removed cover on ASD module and visually checked solder connections ...no indication of cracking or discoloration, etc
- bridged 8 and 10 connectors in ASD modules, applied power, confirmed solenoid movement by sound and feel, started engine and bled ASD from nipple on top, right side of differential
Results - triangular bulb not operating in any mode, cannot determine if ASD is operating during driving by feel

Anything else to check short of replacing ASD module or having it tested? It doesn't look complicated and the circuit scale is pretty large so should be easy to test (not my area of expertise, though).

Since the built in test system does not show a malfunction, is there one or is something else interrelated in some way that is not apparent. Everything else works fine, including ABS.

This experience should be helpful to others, so I really wanted to document and work it to closure.

Thanks!