1990 300SL Instrument Cluster Problem

[waynesworld]

Any help greatly appreciated...
1990 300SL:

Many of the gauges in the instrument cluster stopped working (fuel,speedo,tach,odometer,air temp,economy), but interestingly the coolant temp and clock work fine. The cluster lights up ok and the idiot lights below the cluster seem to all work. The directional lights stopped working at the same time.

I have checked, and swapped, the main fuses with no luck. Also have pulled the cluster and checked the plug connections, re-seated the CIS, again with no luck.

Any help greatly appreciated...

[Gilly]

Wayne(or whoever you are) I have an idea. On the right side of the car there is an area where there are several control modules. I believe you will see the area back towards the firewall. if you were messing around with the CIS-E control module, you've probably been in there already. I believe this car has what is called a BM, or base module. It will be in the same area as the CIS-E control module if it has it. The BM has a clear plastic lid on top of it, there are fuses under the lid, fuses like a GM car has now, the plastic ones. Check these fuses out, there may be a blown one in there......Gilly

[waynesworld]

Thanks for the reply. I did find that base module and checked the fuse, but it looked and checked ok. There was 1 fuse in the top of the module. I will spend some time with it tomorrow... clean the connections and replace that fuse just for good measure.

[waynesworld]

Well no luck! I changed the fuse in the base module, but that did not soleve the problem. Just to be sure the module (relay?) was ok, I pulled the fuse and sure enough the idled bad and the ABS light was on. So I'm still back to square one. I still don't understand why the directionals are involed... there must be something in common.

Any other Ideas... or is back to the dealer time?

[Gilly]

Wayne (I see your name at the bottom now, I'm a car guy, not a computer guy), I'm a little stumped myself. I work at a dealership. Don't know how pressed for time you are, I could probably find something by either checking out some bulletins (for some reason this rings a bell), or by checking out the wiring diagrams. Who knows, maybe a bad ground? I don't know if you've had the cluster out or not. If you can get it out, look around on the back for what looks like a red bulb base, take it out, you may see that it is actually a small piece of electronics board with a printed circuit fuse instead of a bulb, see if that's blown, it would be obvious. Could be that the "carrier" for the cluster has a break in it, I believe that is available seperately, so the cost would be somewhat less than the GNP of Bolivia. Lets take it a step at a time, though, I will try to check out your problem at work on Monday....Gilly

[waynesworld]

Gilly, this problem is a challenge. I appreciate you taking the time to work through it. I pulled the cluster out and looked for the small circuit board you referenced, but could not find it. I took three pictures of the back of the cluster which I will embed below:




I have been also trying to figure out the three other related (I think) problems; turn signals & hazard lights not working, power antenna not working, and release of the hard top just flashing the swithch light. These problems along with the instrument cluster guages not working (excepting coolant temp) seemed to occur at the same time when I got the car out of heated winter storage.

If your interested the links to see the car follow:
http://www.concentric.net/~Whitcomw/images/MB300SL/General/PIC00001.JPG
http://www.concentric.net/~Whitcomw/images/MB300SL/General/PIC00002.JPG
http://www.concentric.net/~Whitcomw/images/MB300SL/General/PIC00003.JPG

Again... thanks for the help.

[Gilly]

Wayne: Boy, that's alot of failures! On the hard top not realeasing after winter storage, what I would try is disconnecting the top control unit. It is in the storage compartment on the floor, behind the passenger side seat. Open the compartment, it is below the false floor in the compartment bottom. For some reason just disconnecting the battery won't have the same effect. Are the power windows working OK? Also do they lower when you try to remove the hardtop? There are fuses in the rear fuse box for the windows and top, be sure to chech them all. I hope I find something in relation to the cluster failure. I do believe that the circuit board that folds up from the cluster board itself is replaceable seperately. If the whole cluster needs replaced, I think you will need to convert to the LED odometer, the mechanical odometer version was dropped. As I said, let me see if I can come up with something at work. I'm assuming you checked over the fuse box thouroughly for any cracked fuse bars. I'll also assume if you had to jump it to get it going that it was done properly and with another 12 volt battery. On the circuit board fuse, they used them in some models, I didn't know for sure if they were used in the early 129's or not, so I'll guess not. The car looks sharp, although I feel that one day an original untouched 1990 SL may be quite collectible. Went through alot of work that a trained eye picks up on right away, the bumpers and cladding from the Sport models are especially attractive. I assume the door panels are all stock? Any work done to the engine? This is the first year of the 104 engine. Lots of people don't know this was also put into the 300CE in 1990. It will be interesting to see if there is any commonality between these problems. The hazards and turn signals are completely inop, or just the indicators in the cluster? Does the hazard switch light up at all? On the radio antenna, only the antenna itself is inop, the radio does work?.......Gilly

[ejsharp]

Instinct tells me that there is nothing wrong with the instrument cluster. The problem sounds like it is fuse related. Read the information usually printed on or attached to the fuse box(s) to identify what fuses control the circuits that are out of order. Then trace those circuits to look for a fault or short or poor ground.

Smiles

[waynesworld]

On the hard top release problem... I did try disconnecting the control unit, but that did not work. Both power windows do work fine. They don't lower when attempting the release as they normally would. It acts like it doesn't start the sequence. When I do the opposite and push the button forward to latch the top, you can hear the hydraulics and the latches pull the top down. The top acted similarly once before and 'fixed' itself, so it may not be related to the other failures.

I have gone through all of the fuses (both front and rear locations) and swapped them size for size, but in different locations to try to identify a rouge one. The hazards and turn signals are totally inop with no light on the hazard switch. I removed the hazard switch and checked continuity. This seemed ok. The radio does work even though the antenna is inop. The battery had gone dead in storage and I charged it overnight on trickle charge. The gauges were ok then, but I did not try the other items... I know that because I alway look for the oil pressure on startup. This was all about a month ago. Then when I started the car a week ago to begin the detailing process, I noticed the gauge problem and then found the other issues.

On the cluster... All idiot lights, those along the bottom and the low fuel level and low oil pressure, work as they come on when the ignition switch is turned to on. Interestingly, they flash exactly 6 times when I turn the key to on and again when I turn to start to fire the engine. I don't recall if it did that prior to these problems surfacing. The coolant temp and clock are the only 'gauges' that work.

Thanks for the comments on the car's looks. The sports model cladding, mirrors, and HID lights from a recent model were added by a past owner. The interior is stock (replacement Blaukpunkt radio/CD). The suspension has been lowered with Eibach springs, added front and rear sway bars from RENNtech, Sport shocks from Bilstein. The BBS RSII 18" Wheels and Pilot MXX3 tires. It handles really well. I do need more power however, and will be looking to do some mods in that area.

Thanks again...

[ejsharp]

The six flashes may be a clue. My BMW will flash a code. Maybe Gilly has an idea about the flashing.

[Gilly]

Nah, I'm pulling at straws now. Maybe I can find something at work tomorrow. Flashing clusters are usually bad signs, nothing I've ever heard of relates to a flashing cluster representing a blink code. Never heard of Beemers flashing a code either, but my BMW experience is slim and long past. God I hope the polarity wasn't inadvertently reversed somewhere in the "dead battery" scenario. You didn't have to jump it at all, just charged the battery? One tip for ya, try to keep the battery charged and installed in the car. I know you may have cold storage with no outlet, so this may not be possible. On the radio, have someone turn on the radio and put your ear to the 1/4 panel, do you hear anything, the antenna motor running, or maybe a click? You'll probably want to start with the basics, see if the 12 volt and signal from the radio are getting to the antenna. In most cases with a stock radio, this is usually opposite of the complaint; usually the antenna goes up, but nothing else happens, no faceplate, no sound. On the hard top, remember that the control unit also controls the windows. The window switches will operate the windows, but the top switch won't is what you are telling me. I'm not sure on the early 129's if the windows need to be synchronized or not, check your owners manual if they mention synchronizing the power windows. On the control unit, I believe that has 3 connectors, you disconnected all 3? One thing I'm cuious about is if you roll down the windows using the window switches, then operate the hardtop switch as though you are latching down the hardtop, instead of trying to take it off, will the windows roll up using the hardtop switch? Curious about the Xenon lights, did the previous owner also install the headlamp range adjustment, or just installed the headlamp units and aim them as best he could?......Gilly

[waynesworld]

Gily, The polarity was never reversed. The gauges worked following that charging anyway. They just stopped over the last week. In answer to the top question. The windows do not try to go up when latching the roof... you just hear the hydraulics pull the roof down tight. I will retry disconnecting all plugs from the top control unit tomorrow and see what happens. As far as the antenna is concerned... I'm not even focusing on it until the other probs are resolved. There is no mention in the owners manual of synchronizing the windows. BTW, how can I recognize the Xenon range adjustment if it exists?

Earl, I have that gut feeling as well that it is not the cluster. I'm thinking that the fuse/circuit/signal that keeps the gauges from working now also impacts the turn signals and top ie: the control unit won't allow the top to unlatch if the car is running, but without a signal it does not know... anyway just swags at this point.

[elau]

Waynesworld,
Its a looker. I would never guess it's a '90. I especially like the lowered look. Sorry can't offer any help, but good luck fixing your problem anyway.

95 R129
98 W163

[Gilly]

Wayne: Easiest way to tell if it has headlamp range adjustment is to drive it at night, you can see the headlamps being adjusted in reaction to dips or bumps in the road. There are level sensors that are utilized also, you would know they were there. It's possible that just the Xenon units were instaleed into the factory 1990 headlamps, I recently became aware that this is possible (installed into a ML430, what a mess!!). I'm thinking this may be the case, because if the newer Xenon headlamps were installed in your car, I don't think the headlamp wipers would be there anymore. Also you would be able to spot the headlamp range adjustment motor in each lamp unit. We'll I'll get going, hope to set aside some break time or time after work to research your problem, at least the service bulletins, maybe I'll bring the wiring diagrams home with me to study also......Gilly

[waynesworld]

Gilly, I looked for something that fits the description of the Xenon range adjustment unit and did not find anything. I don't want to drive the car without the gauges working. I also disconnected all the plugs on the top control unit as you mentioned, but that did not get the top to release. I do believe that the culprit causing the gauge problems is also preventing proper action of the top. I'm interested to see if you came up with anything today.