Help! E34 Instrument Cluster Repair / Need Info

[m3driver97]

I recently completed the removal and repair of the instrument cluster for my 93 M5. Problem was intermittent temp gauge dropping to the left so I was frequently driving without a temperature gauge reading (a little risky with this car).

Read all the forum articles on this repair (bad capacitors) and decided to go ahead and order the caps to replace the bad ones. Decided to try the removal procedure w/o removing the steering wheel (wiggle out between dash & extended steering wheel) which worked out fine.

Somewhere in the excitement of making this repair and the reinstallation of the instrument cluster gauge, I had forgotten to turn off the ignition key and the turn signals (I pulled the unit out between the wheel and the dash w/o removing the steering wheel or disconnecting the SRS) before I hooked up the battery. I was surprised at the size of the spark that I saw when I put the negative terminal back on the battery but completed the job and tightened up the connection. When I got back to the driver's seat, I saw that the ignition switch had been on, along with the left turn signal and the headlights. Turned the key off and put everything else back where it belonged.

The moment of truth was here. I started up the car and was going for a drive to see how effective the repair was in fixing the temp. gauge. The first thing that I noticed was a flashing SRS light (which I had never had before). Not sure how this happened as I never hooked up the battery until all 4 instrument cluster connectors were plugged in and locked and none of the SRS connectors or steering wheel were ever touched. Bottom line, after a few minutes of driving, the flashing SRS light went to a continuous-on SRS light and my temp. gauge started acting up again. Now I am worse off than when I started.

Here are my questions:
1). Is there any tool that I can buy which will allow me to reset the SRS light without going to the dealer? The Peake RS/SRS tool that I found shows that is for use in 1994-2000 BMW's only. Can't find any tool which will handle 1993 or earlier. Am I stuck going to the dealer? If so, what type of charge should I expect?

2). Where is the SRS "error" stored? Is it in the instrument panel logic, the ECU, or some other dedicated piece of electronics?

3). If I buy a used instrument cluster (blue-back unit) and swap out the PC board, is there any special procedure to move the coding plug from my current unit to the replacement PC board without causing yet another problem? I don't want the coding plug to get screwed up causing the mileage to get lost.

Thanks in advance for any help/guidance any of you experts can provide me...

Regards, Brent

[whiskychaser]

I recently completed the removal and repair of the instrument cluster for my 93 M5. Problem was intermittent temp gauge dropping to the left so I was frequently driving without a temperature gauge reading (a little risky with this car).

Read all the forum articles on this repair (bad capacitors) and decided to go ahead and order the caps to replace the bad ones. Decided to try the removal procedure w/o removing the steering wheel (wiggle out between dash & extended steering wheel) which worked out fine.

Somewhere in the excitement of making this repair and the reinstallation of the instrument cluster gauge, I had forgotten to turn off the ignition key and the turn signals (I pulled the unit out between the wheel and the dash w/o removing the steering wheel or disconnecting the SRS) before I hooked up the battery. I was surprised at the size of the spark that I saw when I put the negative terminal back on the battery but completed the job and tightened up the connection. When I got back to the driver's seat, I saw that the ignition switch had been on, along with the left turn signal and the headlights. Turned the key off and put everything else back where it belonged.

The moment of truth was here. I started up the car and was going for a drive to see how effective the repair was in fixing the temp. gauge. The first thing that I noticed was a flashing SRS light (which I had never had before). Not sure how this happened as I never hooked up the battery until all 4 instrument cluster connectors were plugged in and locked and none of the SRS connectors or steering wheel were ever touched. Bottom line, after a few minutes of driving, the flashing SRS light went to a continuous-on SRS light and my temp. gauge started acting up again. Now I am worse off than when I started.

Here are my questions:
1). Is there any tool that I can buy which will allow me to reset the SRS light without going to the dealer? The Peake RS/SRS tool that I found shows that is for use in 1994-2000 BMW's only. Can't find any tool which will handle 1993 or earlier. Am I stuck going to the dealer? If so, what type of charge should I expect?

2). Where is the SRS "error" stored? Is it in the instrument panel logic, the ECU, or some other dedicated piece of electronics?

3). If I buy a used instrument cluster (blue-back unit) and swap out the PC board, is there any special procedure to move the coding plug from my current unit to the replacement PC board without causing yet another problem? I don't want the coding plug to get screwed up causing the mileage to get lost.

Thanks in advance for any help/guidance any of you experts can provide me...

Regards, Brent

Cant help you with 1+2 but depending where you are somebody here has got to have something like Carsoft which will erase stored faults. Mine doesnt have SRS so I couldnt tell if it would work or not. With regard to 3, you can split the 2 sections of the cluster if the back section is still OK. That will leave your chip undisturbed- I have UK gauges but my chip still displays the original km settings. If the back section is shot I dont think its that difficult to swap anyway

[m3driver97]

Thanks for the response Whiskychaser. Hadn't heard about Carsoft before your note but I looked them up -- looks like their product connects to the BMW maintenance connection and to a PC serial port to extract and analyze fault information. Nothing on their web site about this product being able to deal with a SRS fault, although it might have this capability.

As to the coding plug, my concern was whether or not I could screw it up by moving it from one PC board (mine) to another similar board. It appears that it is simple enough to remove it -- 2 latching tabs. Just didn't know if any dealer magic ($$$$) was required to make the coding plug work with a different PC board.

I don't want to do anything that will make the coding plug lose the vehicle mileage because I then have a TMU vehicle which has less value in my estimation.

[attack eagle]

have you checked the sender itself after dropped needle to make sure you are not diagnosing a cluster error when the sender is failing? Checked engine grounds also?

[m3driver97]

Thanks for the suggestion, attack eagle!!

One of the first things that I did with this car was to check the wiring (as well as I could follow it) for any breaks at or near the temp. sensor. I also literally spent hours looking for all the places that BMW put the electrical grounds and probably found 80% of them. All were snug and none had any type of corrosion around them.

That's when I started searching the forums to see what else I could find out about this problem.

When I removed the instrument cluster, I found that I had the later version of the board (=> 09/90) with P/N 62-11-8-363-173. On the board, I found that the 1000uF capacitor had dumped the electrolyte on the circuit board. When I removed the capacitor, I tried to scrape the dried electrolyte off the PC board but it was like light tan plastic and didn't want to budge. Decided to leave it there since I figured that with my luck, trying to scrape this stuff off would end up permanently damaging the board. Replaced this capacitor and also the nearby 220uF capacitor with 25V / 105C versions and thought that would fix the problem. As you can see from the post, I had the same problem as before with the temp. gauge dropping off and then returning to normal.

Some more searching on this problem and electrolytic capacitors in general led me to believe that I still had the problem because of the dried electolyte remaining on the board where the capacitor had leaked. Decided to get more aggressive so I removed the 1000uF capacitor again so I could get a good view of the area on the board. Turns out that the electrolyte crap dried exactly over the 4 PC lands that go to the temperature gauge. My guess is that stuff was intermittently conductive and was shorting out the temp. gauge from time to time.

To scrape the electrolyte off the board, I decided to use something soft & non-metallic so I would be able to avoid gouging the board. I settled on a heavyweight plastic spoon (the kind you can reuse) and filed the end of the handle to a 45-degree angle. I used a large illuminated magnifying glass to see what I was doing and after a little practice, I found that I could actually scrape this stuff off without damaging the board. When I got the majority off I then was able to use the corner of the filed area to clean between the lands and remove the remaining electrolyte. I was amazed at how well this approach worked to clean the board. Hard to tell that there was ever a problem.

Finally I proceeded to replace both capacitors I had previously installed with new ones. Also replaced 2 of the 22uF 40V units with 22uF 50V while I was at it. Now the only thing to do is to reassemble the instrument gauge, reinstall it, and see if the temperature gauge problem is now fixed.

If so, I am down to the SRS light and I'll have to find a way to deal with that. I'll post the results here in any event...!!

[whiskychaser]

I havent seen your board. But what you might think is stuff dumped out of a cap may not be that at all, particularly if its a waxy substance thats a bugger to shift. So did you remove the cap and check with a meter to see if it was stuffed? Carsoft wont affect your coding plug or everybody and his dog would be after it:D I have a cluster sitting around doing nothing. If you want me to pull it apart and pm you pics as I go just pm me

[attack eagle]

did you meter out the sensor itself?
bentley has the impedence at 'cold' and operating temp if you wanted to check.

[m3driver97]

WhiskyChaser... you could be right about the capacitor... I can't be sure that the stuff on
the board leaked out of the capacitor or was there on the board for some other reason. In any event, if it were just a bad capacitor, replacing it should have solved the problem and it hasn't yet.

I'll put the instrument cluster back in tomorrow AM and test it. Too dark in the garage at the present time. I'll post the results of the install.

Thanks for your feedback...!!

[shogun]

Peake SRS tool does not work on your E34, only on cars produced from 1994.
I have the SRS reset tool for your car for sale, new
http://www.bimmerboard.com/forums/posts/551746
If you want one, send me a PM and I will give you my Paypal account.
I will be in Europe from September 17 for 2 weeks, If you need it urgent, hurry up and I can send it out immy after receiving your payment, otherwise in October when I am back.

Read this thread about cluster repair
http://www.bimmerboard.com/forums/posts/569898
we soldered this:
http://www.bimmerboard.com/forums/posts/569942
connectors for the plugs, but inside the cluster, you have to break out a part. As you can see from the pics.
And see this
http://www.bimmerboard.com/forums/posts/467642/

[m3driver97]

attack eagle: Sorry I didn't respond sooner to your suggestion but I got tied up working.

The temperature sensor with the specs in the Bentley manual is the Engine Coolant Temperature Sensor (blue body) which only feeds the ECM.

The unit that feeds the the Instrument Cluster gauge is referred to as the coolant temperature gauge sender and has a brown body.

I have cleaned the connections on both of these gauges several times and have put Permatex dielectric grease on the connections to ensure no corrosion.

I can't be sure that I don't have a damaged wire somewhere between the sending unit and the instrument cluster, but the gauge always works until the car starts to get warmed up. It's only when I am almost at normal operating temperature that the gauge may decide to drop off to the left. So although a damaged wire isn't out of the question, I don't have it high on my list of suspects at the moment.

The second replacement of all the capacitors after I managed to scrape the electrolyte off the board also didn't resolve the problem. Just put it together this afternoon, went for a drive, and had the same exact problem.

One of the forums I looked at had a very similar problem which remained after the replacement of the capacitors. The person stated that the problem was finally resolved after the LCD display assembly was replaced.

I plan to buy a used instrument cluster on eBay, plug it in, and see if my temp gauge works OK. If so, I will swap whatever parts that I need to into my cluster until it starts working reliably. If not, I'll rewire the temperature sender to the cluster connector.

Thanks again for your suggestions...

[attack eagle]

being a 93, shouldn't you just be able to swap the coding plug over to get your mileage on the new cluster?

[m3driver97]

shogun:
Sorry I didn't respond sooner.

As you can see from my previous post, a second replacement of all the caps. after cleaning the electrolyte off the PC board apparently bought me nothing as I had the same problem as before. Was interested in one of your links regarding a blown resistor in the speedometer gauge. Didn't bother to look physically at the temp gauge to see if there was some obvious symptom but the next time I have it apart I'll pull the gauge and look it over carefully.

The plan right now is to order a used instrument cluster from eBay and swap it in in place of my cluster, If the temp gauge behaves, I'll swap parts from this cluster into mine until I get mine working reliably. (PC board, LCD display, temp gauge). If this cluster acts up the same way, I'll rewire from the sending unit to the cluster connector X16.

Thanks also for your info on the SIR3 reset tool. I'll let you know before the end of the week if I decide to order one via PayPal.

Regards, Brent

[m3driver97]

attack eagle:
From a physical perspective, it certainly looks like I should be able to move the coding plug from one cluster to another since there is only a mechanical latch holding it in place.

My only concern was whether or not there is any electronics tie-in between the coding plug and the printed circuit board where they had to match -- i.e. some BMW dealer procedure required to put a different coding plug in the cluster.

The last thing I want to do is to move the coding plug to a different printed circuit board and end up with no recorded mileage for the vehicle.

I guess if I don't hear from someone who has already done this successfully, I'll have to assume the role of guinea pig when I start swapping cluster components to eliminate the problem.

Thanks for your suggestions.. Brent

[Denton]

This is a well-timed thread for me.

I was thinking about getting a used blue-label cluster because I have bad capacitators (lazy tach in cold weather) but when I learned that the mileage would be off the donor car I scratched it off my list.

Let me know if you can move coding plugs; I would consider that if my cap fix doesn't work.

[shogun]

contact Ken Fister or others on his board

Ken Fister - Charlottesville, Virginia USA
97 328i, 95 540i, 97 Hino truck
www.bmwecu.org

there are some people who can re-write the old chip from a new used cluster to fit your car, then the new chip will include your car details, the VIN, and the correct miles too.
At least i know some people on the E34 board which do that for small money. But one thing is for sure, they will not make a fake lower mileage on the new cluster, they are very strict on that.
They just do people a favor by transfering the data from the old chip into the new one, so that they can be proud of their real mileage.

[Denton]

Thanks for the reply Shogun. I'm not interested in odometer fraud, just not interested in having a TMU vehicle or mileage displayed other than my own.

[Ross]

"The last thing I want to do is to move the coding plug to a different printed circuit board and end up with no recorded mileage for the vehicle."

I don't think this will happen. Used car dealers would have jumped on this eons ago.
Mileage and vehicle specifics are on the coding plug, the cluster is dumb without it.

[m3driver97]

Ross:
I tend to agree with your statement about the coding plug. It probably retains the accumulated mileage for the vehicle along with identifying info such as VIN, etc. That way a used car dealer couldn't just swap in a compatible coding plug with lower mileage and have this change go undetected.

That probably also means that if you have a fried coding plug, you either have to go to the dealer or an indy to get a new one properly coded (probably with 0 miles and a TMU sticker).

I am beginning to think that moving the coding plug between equivalent clusters will work OK and carry the relevant vehicle information with it. I'll probably find out soon enough for real when I get a used cluster to experiment with.

[whiskychaser]

Ross:
I tend to agree with your statement about the coding plug. It probably retains the accumulated mileage for the vehicle along with identifying info such as VIN, etc. That way a used car dealer couldn't just swap in a compatible coding plug with lower mileage and have this change go undetected.

That probably also means that if you have a fried coding plug, you either have to go to the dealer or an indy to get a new one properly coded (probably with 0 miles and a TMU sticker).

I am beginning to think that moving the coding plug between equivalent clusters will work OK and carry the relevant vehicle information with it. I'll probably find out soon enough for real when I get a used cluster to experiment with.

Acutally I disagree. My own experience on swapping clusters was that the 'new' one worked fine. Only it displayed a much higher mileage than mine. No evidence of tamper. Nothing. I retained the back section of mine containing the original chip and swapped the front.

[Denton]

I bit the bullet and ordered a used cluster from another 525i, with barely higher mileage than mine...got lucky.

If the caps are good on that one I'll swap it in and use it, while having all the time in the world to mess with my current cluster with bad caps.

[m3driver97]

I wanted to close out this saga with an update since I finally found a resolution to the problem and wanted to share it.

I tried on multiple occasions to get some instrument cluster info (program version) from various eBay sellers but none ever answered my question regarding the program version of the cluster they were selling. As a result, I never ended up with a replacement cluster to use in troubleshooting.

Although I hadn't mentioned it in this posting, I was also fighting another (apparently) unrelated problem. The dash lights would go out after a very short time (if they came on at all) and most of the time would stay off for an extended period of time - even days. I wasn't having any luck resolving this problem either.

Ended up removing the dimmer assembly from the dashboard thinking that the dimmer had an intermittent "open" causing the lights to go out. Jumpered between the gry/blk (B+) and gry/red (inst lights) wires on the dimmer thinking that if the lights came on full brightness then I had a defective dimmer. Instead I ended up blowing F10. Metered gry/red to ground and had 0 ohms resistance. Of all the lights that the dimmer controlled, the only one that I knew I didn't have was the illuminated shifter since the PO had replaced the original with a nice non-illuminated unit. I remembered that when I had removed the console previously (another problem) there was a 2-wire connector with 2 short stubs of wire sitting at the base of the rubber shifter boot. Neither piece of wire had any insulation removed from the end causing a bare wire condition so I left the connector as it was and forgot to insulate the wires with electrical tape before I put everything back together.

Bottom line: I removed the clips holding the leather shifter boot and was able to prod around and find the 2-wire connector. I unplugged the piece that used to connect to the original shifter and tried the dash lights. Problem solved.

What's interesting is that the dimmer assembly was able to absorb the short circuit between the grounded gry/red wire and the bry/blk(B+) without causing the fuse to blow.

And how this ground had anything to do with the temperature gauge only acting up I'll never figure out. I found a set of detailed 1993 BMW wiring diagrams which had some additional information beyond what was in the Bentley manual but I am still unable to connect these two problems together.

Just wanted to thank everyone for their suggestions and share what I found in case anyone else encountered this type of problem.