Success in General Module Repair

[dabenthusiast]

Great, well ill disconnect the batteries. This is my first time ever disconnecting the batteries on my 8 haha iv owned it for about 3-4 years now.
Car is infront of my garage so i will tear it apart now.
Im also dealing with leaky sunroof drain.

[Sniff38]

When disconnecting the batteries, all you have to do is pull both cables from the common ground point located right behind the left side battery (LHD cars). These cables just lead to the negative posts of the batteries. Here's a random photo I found on the internet.

100_0951.jpg

[dabenthusiast]

I thought about it, but i already removed negatives from each battery.
GM is out, hope to have it sent out soon!

[dancerst]

I thought about it, but i already removed negatives from each battery. GM is out, hope to have it sent out soon!

Why not repair it yourself??

[dabenthusiast]

Why not repair it yourself??

Rather not buy a nice solder equipment as i have none, no experience soldering anything. So id rather not have to learn and all that just to have it done.
Cars been acting up bad every morning and i just want it fixed.
I do plan to learn later on on something less important.

[ltbrett]

Just completed the repair today. Thanks for the detailed instructions! I'm not a beginner at microminiature repair work, but I'm no expert either. The circuits around the capacitors you solder are pretty close to the solder pads. I would not attempt this repair as my first go-around. I spent a fair amount of time making sure the solder joints were not short circuiting anything, a process made doubly hard by the old conformal coating.

Brett

[8eights]

I agree! It's much easier to send them out to "E" and he returns them immediately, Send on a Friday and your back up on Friday, The job is done right and no rarely used tools in the tool box, Worked out great for me and many others. And he's a bargain too!

[Sniff38]

^^ What he said.

[BobieM]

^^ Also, What he said. The price is right, he's got the procedure down, and I don't feel like fighting with 20-year-old varnish/sealer all over the board. Mine will go to The EE


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[BobieM]

Scott (EEDegreeToDrive) is a gentleman and a scholar, a great guy to deal with. I pulled my GM last week and sent it to him for repair. He turned it around within a couple of days of delivery, really clean work. I'm very grateful for the help (and the education on the module and its components, via email). If you have any doubts about the job whatsoever, I'd encourage you to send it in.

[EEDegreeToDrive]

I agree! It's much easier to send them out to "E" and he returns them immediately, Send on a Friday and your back up on Friday, The job is done right and no rarely used tools in the tool box, Worked out great for me and many others. And he's a bargain too!

^^ What he said.

Scott (EEDegreeToDrive) is a gentleman and a scholar, a great guy to deal with. I pulled my GM last week and sent it to him for repair. He turned it around within a couple of days of delivery, really clean work. I'm very grateful for the help (and the education on the module and its components, via email). If you have any doubts about the job whatsoever, I'd encourage you to send it in.

Thanks for trusting me all with your modules! As many of you know, I repair them at the price I do mainly so folks don't hack up their modules and leave them for the next guy to fix. Call it a preservation effort.. :-)
(My apologies for not participating in the forum much this last year or so.. I've been pretty busy, and have found the Facebook groups to be more convenient for sharing photos/videos than the forum)

Unfortunately, it seems the GM repair hasn't been resolving everyone's sleeping car issues lately... My process, methods, etc haven't changed, but one I repaired locally, and 2 that were sent to me this year (out of about 12) didn't seem to resolve the issue completely. I wonder if there is some other common failure that isn't being resolved... Perhaps a door module, alarm module, or something going on in the relay module?

Folks with working cars that go to sleep after 16 minutes: If you happen to have your doors apart for one reason or another in the next few months, could you please see if your car still sleeps with the door module(s) disconnected. This will be helpful to know in our collective diagnostic efforts. If anyone wants/needs their GM repaired in the next few weeks and sends it to me, (PM me for details, mailing address, etc), I'll happily look at your relay module for no extra charge.It's been a while since I've had one in my hands, and I don't feel like disassembling my car at this moment!

Other folks that are still experiencing sleep problems, try disconnecting your door modules and repeat your current sleep test. The odds aren't great, but if this somehow DOES resolve your problem, it helps answers two questions:
Will the system will operate without the door modules?
Are the door modules contributing to some wake-up event?

I know the General Module failures aren't unique to the E31, Shogun, E32Fan, and other E32 experts, does the 7 have door modules? What other gremlins have you found that have been known to keep the 7 series awake?

Thanks all!

[adwebinc]

Hi all. I've been pretty busy the last year too so haven't been super active. I am one that sent my module to E for repair. Although it didn't fix my parasitic draw issues, I'm sure it needed it anyway.

I did decide to send my gauge cluster out for repair too since the odometer was something that kept coming on intermittently. The guy said there were some blown capacitors. I just got it back yesterday and I'm getting some other work done on the car, so I will report back once it's back in and running on whether or not it addresses the issue.


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[BobieM]

Thanks, I'll keep an eye on the door module(s). Where is the relay module?

Other folks that are still experiencing sleep problems, try disconnecting your door modules and repeat your current sleep test. The odds aren't great, but if this somehow DOES resolve your problem, it helps answers two questions:
Will the system will operate without the door modules?
Are the door modules contributing to some wake-up event?

I know the General Module failures aren't unique to the E31, Shogun, E32Fan, and other E32 experts, does the 7 have door modules? What other gremlins have you found that have been known to keep the 7 series awake?

Thanks all!

[EEDegreeToDrive]

Hi all. I've been pretty busy the last year too so haven't been super active. I am one that sent my module to E for repair. Although it didn't fix my parasitic draw issues, I'm sure it needed it anyway.

I did decide to send my gauge cluster out for repair too since the odometer was something that kept coming on intermittently. The guy said there were some blown capacitors. I just got it back yesterday and I'm getting some other work done on the car, so I will report back once it's back in and running on whether or not it addresses the issue.

Thanks, I'll keep an eye on the door module(s). Where is the relay module?

Good news and bad news...
The bad news is that I actually installed John C's module in my car and it didn't go to sleep after 16 minutes.

The good news is that I then installed an untested (but recently repaired) module from Wuffer, and it works great after 16 minutes..

My current draw test:
1) Disconnect batteries at common ground

2) Install/Reinstall general module module

3) Reconnect ground of one battery through current meter. (After about 1sec, trunk light comes on, climate control initializes, some other clicks, etc. Sometimes crash control module come on and flashers have to be cycled)

4) I then open and close the door, and then lock it with the key. Current typically drops down to 400-500mA (trunk light disabled/excluded, though my LED trunk lights only add about 300mA :-) ).

5) 16 minutes later, current typically drops down to 40-50mA (depending on if the phone is removed)

In my most recent test, I omitted the EKM body module and the car current actually dropped down to 26.8mA after 16min! (i.e. The GM doesn't depend on the EKM, and it seems the EKM may be responsible for nearly half the sleep current)

I'd love to find a solution to John C and Kevin M's (and now Bobbie's it seems) misbehaving modules. I'm tempted to find a way to erase/disable the 1KB serial EEPROM on the board, or perhaps replace it, in case the 40,000 read/write cycles have somehow been exceeded and is corrupted. (The write frequency is unknown, but it's probably responsible for persistent settings/programming/logged errors, etc.)

[bdiefAZ]

The other module to inspect while the GM is out is the LKM, check for solder cracks. This would not prevent the car from sleeping, but while you are in there...

[Timm]

I'm tempted to find a way to erase/disable the 1KB serial EEPROM on the board, or perhaps replace it, in case the 40,000 read/write cycles have somehow been exceeded and is corrupted. (The write frequency is unknown, but it's probably responsible for persistent settings/programming/logged errors, etc.)

The EEPROM in the EGS has a strange habit of reprogramming itself so that it thinks the car is fitted with a shift-lock solenoid, possibly the General Module has the same quirk!

[BobieM]

And I found my diagram of the car, with the location of the Relay Module. Thanks very much.


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[EEDegreeToDrive]

The EEPROM in the EGS has a strange habit of reprogramming itself so that it thinks the car is fitted with a shift-lock solenoid, possibly the General Module has the same quirk!

Timm-- Thanks for that tip.. I wonder what EEPROM configurable options might cause the car to wake/stay awake incorrectly. I suppose I should see if my software toolchain can talk to these modules. I have a laptop with real serial port, and have used carsoft in the past, can it speak to the GM? Can someone PM me with details on getting BMW DIS or INPA setup?

I'm currently in possession of 2 modules where the car has reasonable operating current pre-sleep (~400mA, which is probably just a few relays powered), and presumably operates mostly correctly, but still won't sleep after capacitor replacement. (I'm checking these modules in my car where I have 2 other modules that DO sleep properly). I've double checked my work under the magnifier, and don't see anything obvious (plus a short would certainly draw more current). I've also diode checked diodes/FETs, looked for shorted ceramic and/or tantalum caps, etc.

It's also important to note, that bench testing the now known-good module and the bad module have the same effect. Neither goes to sleep in my bench setup, so I'll have to 'bench' that idea for now.

A little reverse engineering and Identification of the ICs on the board:
topside:
HD637B01Y0P: Hitachi 8-bit microcontroller, 16k-byte EPROM, 256 bytes RAM, 53 parallel I/O, timers, serial comm.
(aside: This CPU does not seem to be re-programmable, but these Hitachi CPUs are neat because they can get down to very low power.. 3mA in Sleep mode; Also it runs at 1MHZ :-) )
NMC9346 : 1KBit serial EEPROM, presumably for coding, configuration, logging faults (40K read/write cycles, 64x 16-bit registers)
L4938: Power supply for the micro and other parts
U5056: Receiver for Parallel/Serial/Parallel communication - a glorifiee shift register, presumably for simple 1/2-byte module to module communication?
bottom side:
4x ULQ2003L - High current darlington array, 7x 500mA outputs : i.e. 28x 500mA outputs capable of driving relay coils, indicator lights, etc.
3x HEF40106BT - Hex inverting schmitt trigger - These will run up to 18V, so probably used to get ~18 inputs into the GM CPU. Schmitt triggers can also take care of debouncing microswitches "to square up slowly changing waveforms"
6x HEF4021BT - 8bit static shift register - (parallel to serial), probably used by CPU to expand output from it's ~8/16 pins to ~48 I/O
1x CD4053BCM - Triple 2-channel analog multiplexer (selecting one of 6 analog inputs) - The GM receives the analog current measurement from the Relay Module (The GM decides if some kid tried to close their hands in the window/sunroof and disengages the protection relays). Since the CPU doesn't have any analog inputs, it's probably just compared against a fixed threshold.

So-- a few things are possible:
--One of the high current outputs is shorted in the active state, driving the RM or one of the consumer cut out relays active all the time (so the car may be trying to sleep, but the relay is forced on)
--One of the inverting inputs is broken and the GM is seeing an event that would/could wake the car (like the door pin being opened)
--The communication chips between the door modules and GM is broken (which would probably manifest differently than not sleeping)
--The serial EEPROM is corrupted and the car thinks it should have some other kind module/option connected, and not able to communicate with it, it is unhappy (poor software design choice)

[David9999999]

Really interesting info. Does anyone have experience with programming the car in relation to the GM? I have a friend with access to dealership software who may be able to connect to my car and look into it further.

[mnewman]

Hello --

Resurrecting this thread

I just purchased my Fathers 1991 E31 with 76K miles on it from the family. Dad passed away in Nov. 2018 and he never really got to enjoy the car due to all the issues related to the this series. Have the GM symptoms on cold mornings, windows, lights, etc. don't work. Weighing in on my options since the last response was almost 2 years ago. Mr. Scott (EEDegreeToDrive) are you still repairing modules? I have experience soldering and have no problem giving this a go, CAPS on order as well but I'd like to give the founder Scott the business, If interested.

Mike

[cartoonz]

Hello --

Resurrecting this thread

I just purchased my Fathers 1991 E31 with 76K miles on it from the family. Dad passed away in Nov. 2018 and he never really got to enjoy the car due to all the issues related to the this series. Have the GM symptoms on cold mornings, windows, lights, etc. don't work. Weighing in on my options since the last response was almost 2 years ago. Mr. Scott (EEDegreeToDrive) are you still repairing modules? I have experience soldering and have no problem giving this a go, CAPS on order as well but I'd like to give the founder Scott the business, If interested.

Mike

Scott is the GoTo guy on this.

As for your idea of "all the issues related to the this series"... seems you've been listening to people that do not understand or have any training on E31's.

[Spandrel]

Scott should be able to take care of it, but it's also easily possible to do yourself. (I should go back and re-add the pictures to this post. Evidently the forum börked all the tumblr links that I was using for image hosting)

[EEDegreeToDrive]

I just purchased my Fathers 1991 E31 with 76K miles on it from the family. Dad passed away in Nov. 2018 and he never really got to enjoy the car due to all the issues related to the this series. Have the GM symptoms on cold mornings, windows, lights, etc. don't work. Weighing in on my options since the last response was almost 2 years ago. Mr. Scott (EEDegreeToDrive) are you still repairing modules? I have experience soldering and have no problem giving this a go, CAPS on order as well but I'd like to give the founder Scott the business, If interested.

Hi Mike! Yeah! I'm still doing them, shoot me a PM and I'll send you the details. I'm on the E31 Facebook group a bunch too. I actually just bought parts and supplies (conformal coating and cleaner) to do another 50 Modules!

Scott is the GoTo guy on this.

Scott should be able to take care of it, but it's also easily possible to do yourself. (I should go back and re-add the pictures to this post. Evidently the forum börked all the tumblr links that I was using for image hosting)

Thanks for the support gents. Yeah, all my dropbox links were broken too when Dropbox changed things. I commonly refer folks back to your instructions in this post for removing the module. I think I'm going to make a video the next time someone comes to my house in Maryland to do it locally! Someday I'll get my pictures and instructions back up as well!

[mnewman]

Scott is the GoTo guy on this.

As for your idea of "all the issues related to the this series"... seems you've been listening to people that do not understand or have any training on E31's.

Just hasty typing is all, I should have stated "all the common issues" related to this Series. Let's face it, all vehicles have issues especially onces that have push the envelope in tech. Not slamming the E31 I love it.

[Spandrel]

Thanks for the support gents. Yeah, all my dropbox links were broken too when Dropbox changed things. I commonly refer folks back to your instructions in this post for removing the module. I think I'm going to make a video the next time someone comes to my house in Maryland to do it locally! Someday I'll get my pictures and instructions back up as well!

I've gone and added pictures back to the original post (as well as my FTP harness HOWTO) that are locally hosted here, so hopefully they'll stay (they're attachments though, not fully inline)