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View Full Version : BMW E46 GM5 (Body Control Module) Rebuild: Central Locking Relay Replacement doityourself



justinwilson77
03-07-2016, 06:16 PM
DISCLAIMER
The first thing I'll say is DO NOT attempt this DIY if you've never used a soldering iron or have little experience. I'm not an expert but I have used a soldering iron quite a bit and this was still a nerve racking DIY. Regardless, here it goes.

Common Problems:
The Central locking system on E46 BMWs can be a little finicky after 10 years or so. Symptoms include: intermittent door locking capabilities, loss of ability to unlock passenger doors from inside using door latch, and only the driver door unlocking. I'm sure there are many other symptoms out there, this is not a comprehensive list.

Total Cost:
~$45 (Relays and desoldering iron) vs. $140 for sending it off.

Time:
2 hours.

Things you'll need:
Tyco V23084-C2001-A303 (http://www.ebay.com/itm/Qty-2-Tyco-V23084-C2001-A303-Relay-BMW-GM5-Door-Locks-/281136520883?hash=item41750adeb3:g:n-cAAOSwoydWnUvS&vxp=mtr) (Make sure to get the newest ones you can find. Preferably 2015 and up)

Desoldering Iron - I used one I found at Radio Shack (yea they're still around) for about $15.

Soldering Iron

Solder

Flat tip and phillips head screwdrivers

10mm socket wrench

Cutting pliers

Needle-nose pliers

The DIY:

First things first disconnect the battery using a 10mm socket...shouldn't need a picture but let me know.

Next you want to remove the glovebox. There are 6 phillips head screws holding the glovebox in place. You have to pull the top of the glovebox towards you and then down in order to remove.

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Unclip the plugs to the light and the flashlight and set the glovebox aside.

Next you're going to grab that black plastic piece that holds the footwell light. Grab it on the far right and pull that side towards the back of the car and then down. There are two clips on the bottom of that white shelf that you have to clear so make sure you look while you're pulling it back so you don't break them. You can see them best in the second picture, thats what it'll look like when you pull it down.

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Next grab your 10mm socket and remove the plastic nut holding that white shelf in place.

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There are two clips that hold that white shelf in place and their on top of the holder. The one on the left can be seen pretty easily but the one on the right can't due to the wiring harness. Make sure to check as best you can which way the clips are facing. Mine were facing towards the rear of the car on both sides. Pull or push in the necessary direction and pull the shelf down.

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You should see this now. The GM5 is outlined in red. There will also be a zip-tie holding all of the wires together and fastening them to the white shelf...clip that. There are three plugs. All of them have elements that need to be slid to the right in order to be removed. Start with the far right and slide that outer shroud to the right enough so you can get a screwdriver in there and put a little leverage on it to get it the res of the way. Make sure that you pulled the shelf down far enough to clear the other wiring harness. The two plugs on the left are a little simpler. There is a white locking mechanism that can be slid to the right. However, in order to move the white part you have to push in a clip just to the right of it. Push the locking mechanism al the way to the right and it'll push the plug out.

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Once you've removed all of the plugs/zip-ties pull the GM5 out and this is what you'll see.

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Next you have to open up the module. Use a flat tip screwdriver and lightly push it open making sure that the flap is clearing all of the clips.

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Next use you hands to push the module out of the housing. I placed my thumbs on the plugs and pushed towards the opening. Worked pretty well but make sure to not cut the tips of both of your index fingers on the module like I did...:asshat
Be sure not to drop the module while doing this.

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Now you should see the module. The relays for the central locking system have the red box around them.

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Now time to desolder. There are ten posts that need to be desoldered. If your GM5 is like mine, it'll be covered in a rubbery coating. Don't worry that doesn't matter and if anything it will protect the rest of the module while you work on it. The posts are shown in red below:

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Note* the posts to the right of the blue line are especially tricky.

Make sure that when you're desoldering that you don't do any damage to the plating around the holes where the relays insert into.
This is a good resource for understanding what wrong looks like. https://www.bmwgm5.com/bmwgm5/CommonProblems.htm

As you remove the solder, periodically tae a pair of needle-nose pliers and grab the post and wiggle it around a little bit just to make sure it is free from the plating.

The relays may need a little coaxing to come off the module...they don't just fall off once the solder is gone. I used a small pick to get underneath the relay and get it started.

Once the relay is removed, install the new relays and solder.

You should be good as new at this point. Put everything back together and test.

Additional resources:

This guy has a lot of good information on his website, if you're thinking of attempting this DIY you should check it out. BMW GM5 (https://www.bmwgm5.com/default_right.htm)

This video goes in depth on the soldering procedures and some troubleshooting. I highly recommend this video for anyone trying this DIY. BMW GM5 Repair (https://www.youtube.com/watch?v=b0zT2UtEU88)

Finally, feel free to PM me with any questions. I'll be happy to help.

wsmeyer
03-07-2016, 06:35 PM
Excellent write up. Something we'll probably all have to tackle at some point.

Regarding the disclaimer, if you don't see the problem here, don't attempt it.

24854

justinwilson77
03-07-2016, 06:37 PM
Excellent write up. Something we'll probably all have to tackle at some point.

Regarding the disclaimer, if you don't see the problem here, don't attempt it.

24854

:rofl:rofl:rofl

danewilson77
03-07-2016, 06:42 PM
Thanks for the contribution Justin. You left the soldering iron on the dining room table.

Sent from an S6 Edge

justinwilson77
03-07-2016, 06:43 PM
Thanks for the contribution Justin. You left the soldering iron on the dining room table.

Sent from an S6 Edge

I realized that on the way home, my apologies.

BMWCurves
03-07-2016, 06:46 PM
Good write up, thanks for posting!


Excellent write up. Something we'll probably all have to tackle at some point.

Regarding the disclaimer, if you don't see the problem here, don't attempt it.

24854

You're right, I'd she's holding it incorrectly. You should grip it in your fist and with lots of force, not like it's a pen.

fw_fw
03-09-2016, 03:57 PM
Question: Anyone know what the other relays on the GM5 module control?? If I'm going to dig that module out from under the dash to swap 2 out of 6 relays I'd rather do some preventative maintenance and swap all the relays at once, giving me peace of mind that I have all new parts that should last another 10 years.....

az3579
03-09-2016, 05:01 PM
Question: Anyone know what the other relays on the GM5 module control?? If I'm going to dig that module out from under the dash to swap 2 out of 6 relays I'd rather do some preventative maintenance and swap all the relays at once, giving me peace of mind that I have all new parts that should last another 10 years.....

This is a solid case of it it ain't broke, don't fix it.
Electronics are too sensitive to be messing with them for no reason.

fw_fw
03-09-2016, 05:16 PM
This is a solid case of it it ain't broke, don't fix it.
Electronics are too sensitive to be messing with them for no reason.

Not necessarily, if you have the experience and the right tools the actual desoldering, replacement, and soldering is easy, especially with a simple two sided board like this one and something as robust as a relay. If we are talking a multilayered PCB or micro surface mount electronics that's a different story, but still doable with, once again, the right tools and experience.

Besides 4 of the 6 relays on this board are identical, and 2 of the 4 are none to go bad due to age, I would also assume the others would be going bad as well. I like doing a job once and doing it right.....

az3579
03-10-2016, 05:27 AM
Not necessarily, if you have the experience and the right tools the actual desoldering, replacement, and soldering is easy, especially with a simple two sided board like this one and something as robust as a relay. If we are talking a multilayered PCB or micro surface mount electronics that's a different story, but still doable with, once again, the right tools and experience.

Besides 4 of the 6 relays on this board are identical, and 2 of the 4 are none to go bad due to age, I would also assume the others would be going bad as well. I like doing a job once and doing it right.....
We will agree to disagree on this one. :thumbsup

Sent from my LG V10 on Tapatalk

justinwilson77
03-10-2016, 06:31 AM
Not necessarily, if you have the experience and the right tools the actual desoldering, replacement, and soldering is easy, especially with a simple two sided board like this one and something as robust as a relay. If we are talking a multilayered PCB or micro surface mount electronics that's a different story, but still doable with, once again, the right tools and experience.

Besides 4 of the 6 relays on this board are identical, and 2 of the 4 are none to go bad due to age, I would also assume the others would be going bad as well. I like doing a job once and doing it right.....

I get what you're saying, I'd say that if the really wanted to replace the other relays, I would only mess with the other ones with the blue writing. I believe these ones might have to do with either windshield wipers or power windows. I wouldnt touch the other two on the right.

fw_fw
03-10-2016, 07:35 AM
I get what you're saying, I'd say that if the really wanted to replace the other relays, I would only mess with the other ones with the blue writing. I believe these ones might have to do with either windshield wipers or power windows. I wouldnt touch the other two on the right.

That's fair, since there is a known longevity issue with those.....

justinwilson77
03-10-2016, 08:40 AM
That's fair, since there is a known longevity issue with those.....

Well and the thing is too, I dont even know why the central locking fails on our cars..is it a longevity issue or is it some other factor? Either way, just make sure to get the newest relays you can.

az3579
03-10-2016, 03:21 PM
Well and the thing is too, I dont even know why the central locking fails on our cars..is it a longevity issue or is it some other factor? Either way, just make sure to get the newest relays you can.

I'm sure it's just wear. The door locks get used all the time, sometimes several times a day depending on your use. Perhaps one of your previous owners locked and unlocked a lot? :dunno

Relays are pretty simple devices, thankfully.