Sporadic malfunctioning of rain/light sensor or wiper system
I’m chasing down an intermittent problem that I’m having with my rain light sensor. I bought a used replacement and fitted it and after fitting it, and now I have intermittent operation of the auto lamp function.
Searching around, I found a TSB for the 204s that mirrors the problem i’m experiencing. Has anyone seen the same chafing on W212? Trying to check my wiring, but the picture included in the TSB is too dark to help me know exactly where to look in my front fuse box.
Can anyone help me to a better image of the wiring harness, or describe where I can look. I don’t see the rain light sensor fuse listed in the front fuse box, or in any fuse box.
Sporadic malfunctioning of rain/light sensor or wiper system
Clear as mud
Last edited by S-Vibes; Oct 25, 2023 at 06:22 AM.




They work marginally for sometime then gradually get worse until error count is too high. Knowing that you may prefer to eliminate unsoldered module from your vehicle.
These "solderless pins" help render all used modules, useless with poor performance.
Imagine this is like buying 10yr old Michelin tires.
The grooves depth may be nice but the rubber has deteriorated into chewing gum.
Used modules are useless like used tires...

opportunity for easy enhancement 🤘
>>>> Practical soldering... links <<<<
Solderless connector pins...
- cause marginal connections
- cause glitchy unstability
- cause interrupted networking
- cause high retransmits
- cause data latencies
- cause delayed performance
- cause TCM "banging shifts"
- cause confused "gear hunting"
- causes ineffective "adaptations"
- .... as personally researched itchy-hands-on

+++ Other Misc Modules ++++
I conducted a survey to begin mapping the impact of this ubiquitous technology - Available through signature links.
Not all modules are affected similarly because of their functions and bus relationships - Use OBD scanner to gauge active chaos.
Impacts are varied and may appear as-if "randomly uncontrolled chaos" - Actually quite the opposite --> extensively tested disfunctions for really well captured alternative behaviors.
As defined above, latencies are a direct cause of expedited "Parking Drain". The scheduled CAN-B polling carried by F-SAM takes significantly longer to complete. Bus awake is correlated with significant current draw and "need another new battery!".
Less MB struggling means true premium ownership.

Last edited by CaliBenzDriver; Oct 25, 2023 at 04:14 PM. Reason: other module ...
.Looking at the TSB:
“Cause:
LIN wiring harness of rain/light sensor damaged.
Chafe mark on LIN wiring harness at fuse box (see attachments)”
Do you think the reference in the TSB to chafed harness is an additional issue, or is really just what you’re highlighting: soderless connectors? I’m game to attempt soldering connectors, but would like to focus on solving this issue before dealing with all the other potentially soon to have issues modules.




.Looking at the TSB:
“Cause:
LIN wiring harness of rain/light sensor damaged.
Chafe mark on LIN wiring harness at fuse box (see attachments)”
Do you think the reference in the TSB to chafed harness is an additional issue, or is really just what you’re highlighting: soderless connectors? I’m game to attempt soldering connectors, but would like to focus on solving this issue before dealing with all the other potentially soon to have issues modules.
Go ahead double check the TSB applicable scope then decide what you want to deal with :
- the F-SAM fuse box...
- the Rain-Light windshield sensor...
I believe there's a .5% chance a single wire can be wigling in the F-SAM's tub. These wires are bundled in harnesses grouped by individual connectors.
Let's see what pans out...

++++ shafing wires:
...in a plastic tub

Last edited by CaliBenzDriver; Oct 26, 2023 at 01:56 PM.


