CreosoteChris
Active Member
Intro
Hello MBClub.co.uk forum readers – new owner here – I’ve recently acquired a red ’93 220CE, and I *totally adore* it – I actually think it’s my favourite car I’ve ever owned. First time in many years that I’ve bought a car with my heart rather than my head, and I feel like I’m 30 again. I think it’s just fabulous gliding around in my super-elegant retro-chic Merc – I just know I’ve got the coolest vehicle on the road, hands down.
Anyway, the vehicle overall is VGC, and I’m trying to get it to the spec I want, going through the interior, installing a decent stereo (making progress there)….. and my biggest issue – fixing the non-functional driver’s-side seat belt presenter. I’m a half-reasonable home mechanic/tinkerer, kinda looking for some guidance as to where to take the diagnosis from here.
I’ve had a good read of the threads here and elsewhere discussing this subject, and done some disassembly and basic diagnosis – summary as follows:
Symptoms
- Driver’s-side SBP does not operate as expected when door closed
- No whirring noises or other signs of activity
Procedure
1. Swapped door switches (lower door switched used by SBP circuit): Driver’s-side ó Passenger-side
=> Passenger-side stays working, driver’s-side stays inoperative) – NOT DOOR SWITCHES
2. Tried the following: engine running - open driver’s door – close driver’s door - physically pull the extender towards extended position
=> Motorised retraction effort can be felt, resisting the manual effort to extend the SBP arm – POSSIBLE SBP UNIT POSITION-SENSING MICROSWITCH ISSUE (SBP thinks it’s in the extended position even when retracted)
=> See http://www.benzworld.org/forums/w124-e-ce-d-td-class/1504310-230-ce-seat-belt-extender-does.html
3. Uninstalled the complete driver’s-side SBP from the car body
NOTE - the presenter arm can be moved along the track – extending it takes a considerable effort, retracting it a lot less. There is one tooth missing from the nylon cogs that actuate the arm, but the mechanism still seem to run smoothly.
4. Swapped control box units (the Bosch-branded plastic box attached by two screws to rear of SBP assembly): Driver’s-side ó Passenger-side
=> Passenger-side stays working, driver’s-side stays inoperative) – NOT SBP CONTROL BOXES
5. Tried connecting loose driver’s-side SBP to passenger-side harness connector
=> Driver’s assembly connected to passenger-side harness does not operate – SUGGESTS A FAULT WITH THE DRIVER’S SBP ASSEMBLY* Additionally, someone has clearly tried and failed to fix this before, evidence of trim disassembly, attempt to prise open the working control box now sitting on the passenger side – so I wasn’t honestly expecting this to give me a result.
=> Also corroborates (2) above.
*However, I’m not really fully convinced that the driver’s SBP should work when connected to the passenger SBP harness Molex connector, without being properly earthed by fitment to the vehicle chassis.
At this point, I was going to remove the trim piece covering the passenger-side SBP, and try actuating the known-good passenger-side SBP assembly, connected to the driver’s-side harness. However, the trim really doesn’t want to come off, and I am reluctant to exert any more force than I’ve already tried (just for diagnosis, rather than actual fix) for fear of breaking something, and not really getting me closer to a fix.
Looking at the removed SBP assembly (arm completely out) I don’t really understand clearly how the position-sensing is taking place – I’ve seen threads mentioning four microswitches, but I’m not really clear about how to locate or check them. Also wondering if some more experienced / resourceful readers of this forum might be able to advise, or suggest otherwise how I proceed to root cause diagnosis / fix here. These units are obviously sought-after items and now fetch hefty prices - I think that if really necessary I’ll stump up, but reluctant to do so until I’ve explored the fix-it possibilities more thoroughly.
Any advice appreciated
Regards Chris, Manchester
Hello MBClub.co.uk forum readers – new owner here – I’ve recently acquired a red ’93 220CE, and I *totally adore* it – I actually think it’s my favourite car I’ve ever owned. First time in many years that I’ve bought a car with my heart rather than my head, and I feel like I’m 30 again. I think it’s just fabulous gliding around in my super-elegant retro-chic Merc – I just know I’ve got the coolest vehicle on the road, hands down.
Anyway, the vehicle overall is VGC, and I’m trying to get it to the spec I want, going through the interior, installing a decent stereo (making progress there)….. and my biggest issue – fixing the non-functional driver’s-side seat belt presenter. I’m a half-reasonable home mechanic/tinkerer, kinda looking for some guidance as to where to take the diagnosis from here.
I’ve had a good read of the threads here and elsewhere discussing this subject, and done some disassembly and basic diagnosis – summary as follows:
Symptoms
- Driver’s-side SBP does not operate as expected when door closed
- No whirring noises or other signs of activity
Procedure
1. Swapped door switches (lower door switched used by SBP circuit): Driver’s-side ó Passenger-side
=> Passenger-side stays working, driver’s-side stays inoperative) – NOT DOOR SWITCHES
2. Tried the following: engine running - open driver’s door – close driver’s door - physically pull the extender towards extended position
=> Motorised retraction effort can be felt, resisting the manual effort to extend the SBP arm – POSSIBLE SBP UNIT POSITION-SENSING MICROSWITCH ISSUE (SBP thinks it’s in the extended position even when retracted)
=> See http://www.benzworld.org/forums/w124-e-ce-d-td-class/1504310-230-ce-seat-belt-extender-does.html
3. Uninstalled the complete driver’s-side SBP from the car body
NOTE - the presenter arm can be moved along the track – extending it takes a considerable effort, retracting it a lot less. There is one tooth missing from the nylon cogs that actuate the arm, but the mechanism still seem to run smoothly.
4. Swapped control box units (the Bosch-branded plastic box attached by two screws to rear of SBP assembly): Driver’s-side ó Passenger-side
=> Passenger-side stays working, driver’s-side stays inoperative) – NOT SBP CONTROL BOXES
5. Tried connecting loose driver’s-side SBP to passenger-side harness connector
=> Driver’s assembly connected to passenger-side harness does not operate – SUGGESTS A FAULT WITH THE DRIVER’S SBP ASSEMBLY* Additionally, someone has clearly tried and failed to fix this before, evidence of trim disassembly, attempt to prise open the working control box now sitting on the passenger side – so I wasn’t honestly expecting this to give me a result.
=> Also corroborates (2) above.
*However, I’m not really fully convinced that the driver’s SBP should work when connected to the passenger SBP harness Molex connector, without being properly earthed by fitment to the vehicle chassis.
At this point, I was going to remove the trim piece covering the passenger-side SBP, and try actuating the known-good passenger-side SBP assembly, connected to the driver’s-side harness. However, the trim really doesn’t want to come off, and I am reluctant to exert any more force than I’ve already tried (just for diagnosis, rather than actual fix) for fear of breaking something, and not really getting me closer to a fix.
Looking at the removed SBP assembly (arm completely out) I don’t really understand clearly how the position-sensing is taking place – I’ve seen threads mentioning four microswitches, but I’m not really clear about how to locate or check them. Also wondering if some more experienced / resourceful readers of this forum might be able to advise, or suggest otherwise how I proceed to root cause diagnosis / fix here. These units are obviously sought-after items and now fetch hefty prices - I think that if really necessary I’ll stump up, but reluctant to do so until I’ve explored the fix-it possibilities more thoroughly.
Any advice appreciated
Regards Chris, Manchester