Topic: keyfob issues after replacing the car battery

[Rogue]

Thanks to the pandemic it's been quite a while since the Mrs needed to drive GXPsy. The battery in the car was 3 years 4 months old (3 year warranty, of course) and wouldn't hold a charge. So, we replaced the battery. Put the key in the ignition....Vroom. The engine started right up. She drove to work today, and when she tried to use the keyfob to lock GXPsy nothing happened. Yes, it's a possibility the battery in the keyfob is dead. I can't check that until this evening. Still, it seems odd that everything worked before we changed the car battery, and now it doesn't work after we changed it. Is this a known issue? If so, previous battery replacements have not had this problem. Ideas? Sugestions? Thanks.

[Steelmesh]

I have had a similar issue for a few years now where I can unlock but can't lock using the fob. Solving this not at the top of my list because I have bigger challenges with my build.  When the issue started I had to stand there and hit the lock button 15 times before the car would lock, I also swapped fobs and batteries with no change, again unlocking responds right away. I have just been locking the doors manually lol.  Doesn't using the fob to lock the car activate some security features though, where manually locking the doors wont?

[Sly Bob]

That IS bizarre Rogue. We know that the early 2008 cars had an issue like this when the battery was changed but as you said, you've changed it in the past without issue. Is the TPMS info on the dash all "--"?

[wspohn]

I've just been through this - see https://www.solsticeforum.com/threads/door-lock-actuator-key-fob-issue-solved.161432/

But definitely do check the fob battery first!

[Sol Asylum]

I have fixed a number if key fobs over the years now and besides bad battery you can also have a broken solder joint on the board both where the battery terminals attach as well as were components are soldered onto the board.  So check and reflow the solder sometimes that fixes the issue.

Another problem source in the fob is the rubber membrane of the buttons can break down.  There should be a little black disk under the button that is conductive and that over time can wear out and no longer make connection.  You can buy new fobs on ebay for a few dollars like $5 or so.  Take the board out of your current fob and put it into the new case or if the membrane is the same just swap that part into your old fob, either way you won't even need to have the car programed to the new fob since you are still using the old fob.

And last but probably should have been first, if you have a second fob see if the problem is present with the second fob if it isn't you know it's a problem with the first fob and not the car.

[Steelmesh]

I just dissected my one FOB, great call Sol!!!!

[Steelmesh]

My other FOB has the same broken solder joint there too! After soldering them, the problem persists.   Next I tried to use the unlock rubber button pad to activate the lock button and it works if you get the angle just right.  Both my batteries are at 3.2V where 2.7V is considered dead.

Digging deeper it gets interesting with the ohm meter on the black pads:

With both my button pads considered:
Gray silicone = open circuit
Unlock buttons = 1-2 Megaohms
Lock buttons = 4 Megaohms to open circuit (on the one pictured below)
Trunk buttons = 0.5-2 Megaohms
Panic buttons = 40 Kiloohms - 1 Megaohm

Notice the Lock button pad is thin around the edges, and the ohmmeter readings suggest that layer of conductive silicone/rubber is thin.

[Sol Asylum]

If you buy those Ebay fobs they come with new batteries too.

[Steelmesh]

If you buy those Ebay fobs they come with new batteries too.

Both my fobs being bad I thought it was a chassis system fail this whole time

I got one ordered up thanks again for the assistance!

[Rogue]

Lots of good responses here, guys. Thanks. A tip of the hat to SlyBob...not only does the keyfob not work, but the TPMS is also whacked. I couldn't check that until after Pat got GXPsy back home this evening. What else can I do to try to diagnose this? As is typical, I don't want to have to take it the dealer.....Also, both keyfobs give the same results...nothing. Batteries in them are good, and none of the typical solder issues are present.

[Sol Asylum]

How long was the battery dead before you replaced it, do you know?

[Sly Bob]

Now that IS odd, first time that I have heard of a 2008 having that happen after several battery changes. It concerns me as I have a 2008 as well although I didn't have to get the module programmed even when the car was new. Wonder if the RCDLR has to be programmed again or maybe it just crapped out this time and has to be replaced?
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#08-03-16-001B: Key Fobs Inoperative, TPM System Not Reading Correctly - Dashes on Al Four Tire Readings, DTCs C0775, C0569, B3105 Set, Unable to Program TPM Sensors (Reprogram RCDLR) - (Jul 31, 2008)

2008 Chevrolet Cobalt, HHR, Malibu
2008 Pontiac G5, G6, Solstice
2008 Saturn AURA, SKY

Condition
Some customers may comment that the key fobs are inoperative or that the TPM system is showing dashes as the reading for all four tires.

Technicians may find DTCs C0775, C0569 and B3105 set simultaneously in the RCDLR module.

In addition, the technicians may find Tire Pressure Monitoring sensors are unable to be programmed to the vehicle by adding or releasing pressure to the tire while the vehicles in the TPM learn mode.

Cause
These conditions may be caused by the following:

• The RCDLR may lose its transmitter and tire pressure monitoring data from its memory if a low voltage condition occurs on the vehicle.

• The ability for TPM learning by adding or releasing pressure to the tire has been disabled in the RCDLR.

Correction
Reprogram the RCDLR with an updated software calibration to address both issues listed above.

Once the RCDLR module has been reflashed with the latest software and calibrations, the following may also be necessary:

• Relearn all keyless entry transmitters.

• Reconfigure the tire pressure placards and the tire type.

• Relearn the tire pressure sensors.

Refer to SI for the procedures to relearn transmitters, placard and tire type configuration and tire pressure sensor learn.


GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

[Sly Bob]

At least if you have to buy a new module it's not TOO pricey and any independent shop should be able to program it if you haven't got access to a Tech2 or something equivalent. Is there a possibility there is a blown fuse or something and the module isn't getting power?

I believe this is the correct one but don't take my word for it...

https://www.gmpartsstore.com/oem-parts/gm-tire-pressure-monitoring-system-receiver-25974373?c=az0x

[Rogue]

How long was the battery dead before you replaced it, do you know?

About one month. The car was parked due to the Mrs being in a "work from home" status. It just didn't get driven. The few times she did have to go into her office she took the Trailblazer SS.

[Rogue]

Sly Bob - I may try to do a TPMS relearn and see if that does any good.

[Sly Bob]

Rogue, did you get things working again?