Roll Bar Inoperative after tire change.

[tecqboy]

I just had new tires put on my 91 Sl300. Now my roll bar will not deploy when pressing the switch. There are no error codes in the controller and the self diagnostic lamps in the VDO and the switch do not light. The soft top is working OK. I assume that when the car was on the hoist, the wheels dropped down enough to actuate the two roll over switches on the rear suspension. Can anyone tell me how to check out these switches and or reset? Another strange but interesting problem. Thanks Tod

[bobterry99]

I assume you knew to check socket #7 on the diagnostic connector for those codes. Tod, you might check this thread which explains how to adjust the limit switches and then to test their operation. If that all works fine, then I guess the next check would be the control switch. It works by grounding terminals 3/4 on the Y-connector of the soft top controller (the "Y" is the lonest of the three on the controller).

[tecqboy]

I did the a thread search and I got a bit confused as to the correct procedure to clear the roll bar errors. Here's what I have.... Connect a current limited LED from pin 7 to plus 12volts (pin 16) (noted that LED is polarity sensitive). Ground pin 7 for 2 seconds to read error code. Ground pin 7 for 6 seconds to clear error code. LED should light whenever pin 7 is grounded. Is that correct?

Thanks for the link in the above reply. I didn't realize the suspension roll limit switches had a test (adjust) switch position.

I'll work on this again in a few days and let you know

Thanks: Tod

[tecqboy]

OK, I've been able to clear all of the error codes except 1 flash. The roll bar is still inoperative. So, I've searched for a list of what the codes indicate, but to no avail. Also, in my search I ran across a thread which said that there is a seperate module for emergency deployment of the roll bar. Is that true? That would complicate diagnosing. It worked before the tires were changed, and in my experience, it's always what was done last that is most suspect. Anyhow Bob; one flash = what? Thanks Tod

[tecqboy]

I found the list of code meanings on "the other forum". One flash means the roll bar is OK and should be working. But it isn't. Always strange problems with this car. Tod

[bobterry99]

Yes, there is a separate controller for the roll bar emergency deployment. It also controls the belt lock relay of each seat.

[tecqboy]

Thanks for that info Bob. I have no errors and one flash in my roll bar controller and no errors in my soft top controller. The soft top works fine. The roll bar does nothing, that is, not even the pump runs when the switch is pressed. The LEDs in the roll bar switch flash once when the ignition is first turned on. The roll bar light in the VDO goes out after I start the engine. The limit switches on the rear suspension are in the function position. Here is another instance where I could probably trace this out if I had an electrical diagram. I repaired Ampex video recorders for years and they were infinitly more complex both electrically and mechanically than this car. Can I assume that the dash "operate" switch pulls a ground? I am also going to assume that there is a relay outside the actual controller which closes to run the pump and actuate a set of hydraulic valves. No? Thanks Tod

[bobterry99]

All of your assumptions are correct. Circuits don't get any simpler than the ones for this system, as nearly all components wire directly to one of the two controllers. Inputs are sinking (ground is switched), and outputs are sourcing.

The roll bar switch is wired to sockets 3 and 4 of the soft top controller's "Y" connector -- it's the longest one of the three on the controller. The soft top controller operates the hydraulic pump through a relay located at the pump assembly in the bottom of the trunk. The signal comes from socket 7 of the "X" connector.