Illuminated rollbar lights

[Crew]

The dash rollbar light and rollbar switch lights (2 red blinking arrows) illuminate 2-3 seconds after star-up. Everything seems to function fine (windows, power top, rollbar etc.) I've changed the battery and replaced the rollbar fuse located in the trunk. What else should I try????

Any help is most appreciated!

Regards,

Crew

PS. I tried the search function... Not much luck.

[Eli (NJ)]

Check the rollover protection switches on the rear axle. I think your blinking lights mean one of them is inoperative.

[Crew]

I checked the switches on the rear lower control arms by starting the vehicle then activating the levered switches. Neither switch activated the rollbar to the raised position??? I wish a repair manual/CD was available for this model... Great car, but a pain to diagnose w/o an algorithmic flowchart.

Anymore ideas!!!!!!

Thanks Eli,

Crew

[Eddie Gilmartin]

My lights flash after start up also. I thought that was normal. Roll bar works fine via switch, but you must follow the procedure in the manual to lower/raise. I've never tried to raise it via the sensors on the back axle. I thought they were for ride heigth adjustment.

[Crew]

My understanding is that the switches on the lower control arm are activated as the car rolls excessively left or right (the graceful Ford Explorer manuever.) However, I may be looking at the wrong switches??

Crew

[bobterry99]

Read the codes from the diagonistic connector Pin 7 as explained in many places in the Shop Forum. Then refer to the chart below to determine why your Switch is lit:

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

[Crew]

OK. After researching past posts, I'm even more confused. It appears that 1994 was a year of transition from analog to digital on some models. I have a 1994 sl320. Does anyone know if the output signal from the x11/4 port is analog or digital on this particular vehicle (ie. will a homemade LED setup work.) So far, no signal.

I really appreciate the help!!!! Hoping to get to bobterry99's codes soon.....

Crew

[bobterry99]

The signal is surely digital.

See Steve Brotherton's explanation of retrieval: Code reader for 1995 E320

[Crew]

OK! Finally, back at it! I got one (1) flash... This indicates no faults in the system??? Do I need to go further back into the system? Maybe in front of the control unit? There most be some sort of rollbar position sensor. After investigating and observing the rollbar in action, I beleive the rollbar in the lowered position is being "held back." Then, when triggered to ratchet-up, it is released and mechanically pops-up (spring?) Where would such a position sensor be located? And what is the test procedure?

Any help is most appreciated!

Crew

[bobterry99]

One flash on PIN 7 means the controller recognizes no faults. It is intuitive that the controller is driving the warning lamps, so here is a contradiction which suggests a possible problem with the controller. But my hunch is that the controller is fine and the trouble is elsewhere.

All I can suggest at this point is that a problem exists in the electrical circuit for the warning lamps. Last summer a friend of mine was troubleshooting the electronics in my instrument cluster because I had no dash lights. I remember at one point the warning indicators lit on the roll bar switch and I became worried. The problem went away, and I don't remember if anything specific was done to correct it. I think it must have been related to the instrument cluster though and had nothing to do with the roll bar system.

It may be worthwhile to verify the automatic operation of the rollbar. 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".

Regarding Crew's assertion that there is a rollbar postition sensor...Yes, there is such a device. A limit switch detects that the roll bar is in the lowered position and inputs this to the convertible top controller. But I believe it has nothing to do with roll bar operation or the warning indicators.

Sorry, but I don't think I can be of further help. This is going to require an expert.

[Crew]

bobbterry99,

Thanks for all your help. The rollbar did not deploy after testing as you described. I also discovered that there is no change in symptoms or function with trunk fuse #4 (rollbar,seatbelt lock) removed. Possible problem with the fuse curcuit? I stopped by the dealer today. They were busy, but hooked up the diagnostics and confirmed no faults detected. I made an appointment for Friday... Very frustrating! Will let you know the results.

Crew

[Crew]

Just wanted to give a quick update on this issue that is now in the dealers hands. Apparently, there are other methods/locations to retrieve diagnostic codes. Twelve (12) codes were detected! Ten codes identified a problem with the passenger's seatbelt system. Since the #4 fuse (rollbar control/seat belt lock) blew last year, the mechanic suspects a connector/ground problem with that circuit. Today, they will proceed in that direction.

Crew

[Crew]

The issue is now back in my hands. The dealer has found the controllor and one ram (actually a switch within) bad. Total turn-key out the door bill $5400! Not gonna happen. I contacted a couple of recyclers on the West coast... Controllor and ram, approx $250 and $600, respectively. Installing the controllor should take 10 minutes, but the ram is another story. I thought MBenz posted pics of a pulled ram unit?

Crew

[bobterry99]

As I understand the situation, your problem is that the fault indications on the dash are lit and your roll bar does not activate automatically when you test it. If so, I would simply replace the control unit and see where that leaves you. I am going to guess that this fixes everything and you do not need a "ram".

And hey. Who did you contact to locate those used parts? My usual sources for used items have nothing for the R129.

[Crew]

bobterry99,

The source for the used controller and ram is:

They actually have a several w129's in stock they draw from.

I made a trip to the dealer this morning hoping to get a good look at the access and involvment of the ram unit. Not too bad. However, the senior mechanic informed me that it is likely that the controller was taken out by the ram. But it is not 'neccessary' to replace both rams. (I was told Mercedes has updated the ram units and if one is bad, they both get replaced for operational compatability.) I could simply drive with the rollbar in the up position at all times, except when the hardtop was installed. If the rollbar was automatically deployed, the excess current draw of the defective ram could take the controller out again. I will start by installing the used controller... And call it day. After I receive and install the controller, I'll let you know the results...

Crew