1991 129 500sl top issues

[pollockd17]

decided to take the hard top off after winter and behold when I push the switch it just blinks at me ran a scan and came up with code 4. Checked the micro switches open and closed and both switches check out. I can clear out code 4 but it comes back when I activate the switch, another thing is that I have a code 8 which I cannot clear. One more thing the roll bar does not work but when I turn the key on both the roll bar switch and the top button lite up for a second or two,HELP!!!!!!!!!

[tecqboy]

Errors 4 and 8 are both left side limit switch codes. Have you tried just excercising the switches a few times? Sometimes they just need a little action to clean up dirty contacts. Are there any roll bar error codes?

[pollockd17]

I don't know how to retrive roll bar codes and will this roll bar failure affect the top operation?????

[tecqboy]

Roll Bar Codes and Reset Procedure.

Locate the diagnostic connector: Under the plastic cover near the hood-up switch on
the passenger side of vehicle near the strut mount.

Connect LED + to pin 16 (+12V) Connect LED – to ground ( Pin 1 ). Use an LED with resistor.

To read error code: Use a push button switch to short pin 7 to ground (Pin 1) 2 to 4 Seconds.

To Erase: Close switch 6 to 8 seconds.

Code 1 = No faults in system.
Code 2 = Roll Bar Control Unit
Code 3 = Voltage Supply
Code 4 = Driver Seat Belt Lock Relay (K18/2) open or short circuit to terminal 30 and/or 31
Code 5 = Passenger Seat Belt Lock Relay (K18/3) open or short circuit to terminal 30 and/or 31
Code 6 = Roll Bar Deployment Solenoid (Y57/1) open or short circuit to terminal 30 and/or 31
Code 7 = Left and/or right rear axle switch open or short circuit to terminal 30 and/or 31
Code 8 = Roll Bar Warning Lamp
Code 9 = Roll Bar Warning Lamp and/or impulse counter held too long to erase malfunctions
Code 10 = SRS Control Unit

[500SL4ME]

I assume that is pin #'s for 16 pin, do you have same info for 38 pin connector?

[tecqboy]

I have this in my e-notes. It came from somewhere else on this or the MB World forum. Unfortunately it doesn't list which pin goes to which switch, so it really won't be of much help. I have seen the info you're looking for someplace, but I can't seem to find it. It's not on the crappy CD manual I have. I've always gotten my top to work by following down the error codes to the bad switch. I've never had a problem with the controller itself or the wiring harness. The switches recover after a spray of contact cleaner.




The hydraulic pump is switched by a relay mounted on the pump assembly in the trunk.

The top switch works by grounding socket #1 (lower top) or socket #2 (raise top) of the "Y" connector at the top controller. The Y connector is longer than the other two -- those are the "X" and "Z". The three connectors are labeled on their male sides attached to the control module.

If the top switch checks-out, then you might try verifying that all inputs from the various limit switches are working properly. When a switch closes to signal the controller, it does so by completing a circuit from the controller to chassis ground. All of the switches are wired to the Y connector of the soft top controller. You'll need a basic multimeter or other device for measuring continuity between the inputs and ground.

To access, open the storage compartment behind the passenger seat. Remove the plastic cover that protects the soft top controller by loosening three 10mm plastic nuts. Now remove the two 10mm nuts that are securing the controller and lift it off of its mounting studs. Now you should be able to easily separate the "Y" connector from the controller.

Looking at the connector you will see two rows of sockets numbered sequentially. Nearly all of these are inputs from the switches, though some are not used. You proceed by putting the top in "Position 1" and checking all the switches and then repeating the same for "Position 2". The info below shows which inputs should be open and which should be closed for each position. Have the ignition off while you perform your checks. Note that you only need to check 17 inputs.

Position 1 (Top closed, windows up, roll bar up)
Open: 10, 22, 27, 29, 30, 31
Closed: 16, 17, 18, 19, 20, 21, 23, 24, 25, 26, 28

Position 2 (Top open but storage compartment cover open, windows and roll bar down)
Open: 16, 17, 18, 19, 20, 21, 23, 24, 25, 26, 28
Closed: 10, 22, 27, 29, 30, 31
***************

[pollockd17]

Thanks for the info I'll try the various tests this weekend and let you know the results. Thanks again....