500sl Soft Top And Roll Bar
 

Hello everyone! I have a problem with my 1991 500SL soft top and roll bar. When I press the control button for either one there is no response/noise from the system. I have checked all fuses and ran a system check, and came up with a couple of fault codes which are: 4, 5, 16, 23, 27. I have been able to erase all of them except for 27. If there is anyone out there that could identify the faults that I have mentioned and assist me in repairing the problem please do so. I would appreciate it, thank you.:(

Code interpretation
 

4 = left compartment cover closed switch
5 = right compartment cover closed switch
16 = roll bar retracted switch
23 = roll bar control unit (gulp!)
27 = insufficient voltage

I suggest troubleshooting code 27 first. The system is looking for a voltage of 11 to 14 volts at the soft top controller. The controller is under a plastic cover inside the storage compartment behind the passenger seat. You can measure the supply voltage by removing the "X" electrical connector and checking between sockets 10 and 12. But first...

Is your battery weak? If not, double-check fuse number 6 in the main fuse box at the firewall.

Post again for further assistance.

You were absolutely right, the battery was week I couldn’t even start the car with it. I replaced the battery, but came up with a new problem. Now both of the system control buttons constantly stays on (lighted up), because of this I cant run a system check. Any suggestions? Oh by the way, how bad is fault # 23?

Control Unit
 

It is $1650 from the dealer... After extensive research I found a used unit for $200.

Crew

Crew you think there is a problem with the control unit? If so where can I get the one you found?

Making good progress
 

The soft top and roll bar button lamps remaining on does not prevent you from retrieving codes. Try it. You should find you have at least one code stored in the controller.

As for the roll bar, you should retrieve the codes for that system. The associated socket on the diagnostic connector is #7.

If you do a search on Crew and roll bar, I think you will come across a thread where he describes problems he had which resulted from a faulty roll bar controller.

I had two issues: 1) The control unit was bad. 2) The passenger side ram unit was drawing excessive voltage. The dealer remedy was to replace the control unit and both ram units (new upgraded rams are incompatable in parallel with pre-98's... Total cost: $5600. I opted to replace the control unit with a used module, and drive with the rollbar in the "up" position to avoid possibly blowing the control unit again.

I believe the source for the used control unit is nested somewhere in my previous posting of this mess. As I stated, after extensive and time consuming research, I found a used module for $200. I recall finding several used units in the $800 range.

Good Luck!

Crew

Updat on my progress
 

Yes, there is movement! New update on my progress. I was able to read the fault codes once I started the engine, fault 23 came up again and I wasn’t able to erase it. After the code was blink out the roll bar switch started blinking constantly. I attempted to operate the roll bar with it and yes it did work properly but the switch still constantly was blinking. I attempted to operate the soft top but no luck. Now this is the strange part; I activated the open top switch and the windows/roll bar came up and the top said stored in it’s compartment. I activated the close procedure and nothing happened. Once again I activated the open switch and the windows/roll bar went down and no movement from the top. Nothing happens when I press the close button except for noise from the hydraulic pump in the back working. I attempted to read the fault codes form the roll bar bay shortening socket #1 to #7 on the diagnostic connector; but I’m not seeing anything happening. Any ideas what’s wrong guy‘s?

Are you trying to retrieve the roll bar controller codes from pin 7 using an LED and grounding the pin for 2 to 4 seconds? If so, then this could be a problem with just the diagnostic circuits for the controller. The 23 fault code from the soft top controller could be confirmation of same.

What are the current fault codes from the soft top controller (diagnostic pin #10)?

"Nothing happens when I press the close button except for noise from the hydraulic pump in the back working."

This may seem obvious, but have you inspected the hydraulic level in the reservoir located under the spare tire in the trunk to ensure it is full? By default, this could be sending the control unit mixed messages.... Who knows what artificial intelligence Mercedes has programmed into that damn control unit??? :>

Crew

the next step
 

Than you for rippling. Yes, I did try to retrieve the fault code from pin #10 and #7. The only fault that I am getting is #23, from pin #10 no response from pin #7 on the diagnostic connector. I also check the level in the hydraulic unit, it’s good, but I think it might be time to change the fluids in it.

Regarding the roll bar, since it works manually it may be worthwhile to check the automatic operation. The control arms for the left and right rear suspension have limit switches which are clearly visible from the rear of the car. There is a two position switch on each of these switches. To do the test, put the selector of one of the two switches in the "Arretiert" position. Now drive the car to a speed of greater than 6 mph and hit the brakes -- the rollbar should deploy. When finished, return the selector from "Arretiert" to "Function".

As for the convertible top, the existence of some specific codes in the controller memory will prevent the system from operating. But 23 is not one of these. Something else besides the roll bar controller is wrong.

I suggest checking all of the limit switch inputs to the soft top controller. There are two ways to do this.

The "official" and surely the easiest way involves accessing a connector located behind the passenger-side foot rest and installing a jumper between sockets "1" and "3". This places the soft top controller in a special diagnostic mode for evaluating inputs.

The other way involves accessing the "X" connector to the soft top controller and checking the inputs electrically with a continuity tester or battery and LED. This is the method I used before I was aware that any diagnostics at all were available for the system. I mention it only because I have not used the official method, nor have I ever attempted to locate the connector in the foot rest.

If you decide to continue troubleshooting your convertible top and want to check the inputs, decide on a method and I will provide further instruction if you wish.

instructions
 

If you could please, send out the instructions on how to do it the official method. As for the roll bar test I will attempt it right now. Thank you very much!
;)

arr320, your problem sounds similar to one I had after jumping the battery. I don't know if you've checked this already but, there's a fuse on top of a relay (OVP relay I think) in the engine compartment at the passenger shock tower. In my case, this fuse blew after jumpstarting the car 3 or 4 times. My top was half operational (closes but opens not) and the same warning lamps were on.

Chek the fuse and the relay before you spend any great amounts, hope that's it.
Eli.

To check the soft top controller inputs using the contoller's diagnostic mode, follow this step-by-step procedure:

1) Close the soft top manually or automatically. Have the windows up. The correct position for the roll bar depends on the version of your soft top controller. Let's assume it is the raised postion. If this is incorrect, a fault code for the roll bar lowered switch will falsely appear later in the test -- no big deal.

2) Erase as many diagnostic codes from the soft top controller as possible. I suppose in your case 23 shall remain.

3) Switch off the ignition.

4) Install a jumper between sockets "1" and "3' of the "X11/12" connector located behind the passenger-side footrest.

5) Switch the ignition on.

6) Push the soft top button forward for two to four seconds as if you were trying to close the top.

7) Read out and record any diagnostic codes for the soft top controller.

8) Remove the jumper from the connector X11/12.

9) Lower the top, roll bar, and windows either manually or automatically.

10) Open the soft top compartment cover and move it to its raised position. I recommend doing this manually. Use the special Mercedes wrench to release the latches if necessary.

11) Switch the ignition off.

12) Re-install the jumper on X11/12.

13) Switch the ignition on.

14) Push the soft top button rearward for two to four seconds as if you were trying to open the top.

15) Read out and record any diagnostic codes for the soft top controller.

16) Remove the bridge.

********************************

Now then, I have never used the procedure just described. But it is intuitive what to expect. In each of the two convertible top positions the controller compares the inputs against a reference once the top switch is pushed, and errors are reported by diagnostic code. Note that step 10 of the procedure was necessary so that the controller could verify the compartment cover raised input switches on and that the cover closed and latched inputs switch off.

Good luck. If you will post the codes you find, I will look them up for you and explain further steps.