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Gauges start jumping around and my stereo stops working?

Tiny
DTB0YZ86
  • MEMBER
  • 2004 PONTIAC GRAND AM
  • 3.4L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 138,000 MILES
My car has been acting weird lately. All my gauges start jumping around and my stereo stops working. It would just die then hard to start. Anyways I checked the BCM, and it had water damage on the connectors. They were green. So, I cleaned them off with electric cleaner plugged it back up and now it won start. Security light comes on but it's not flashing, I hear the fuel pump come in just no crank. I ordered a new BCM, it just needs new connectors. Could it be a security issue? Pass lock? The dome inside lights won't come on or stereo either. But the security light isn't flashing, it's just on.
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Friday, March 22nd, 2024 AT 6:48 PM

27 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

It sounds like the battery was failing or not being recharged. Is it fully charged? If so, turn the key to the run position. Allow it to remain in the on position for approx ten minutes.

If it is an issue with the anti-theft system, the light should turn off and allow the engine to start.

Try this and let me know what you find.

Joe
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Friday, March 22nd, 2024 AT 10:06 PM
Tiny
KEN L
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Security will not be an issue if the light is not flashing but a bad BCM can cause the not start issue and the gauges jumping around, if the engine is cranking over strong the battery is okay. I have also seen a bad alternator cause this issue as well due to throwing AC voltage.

This guide can help see if that is the problem once the engine is running:

https://www.2carpros.com/articles/how-to-check-a-car-alternator

I would run the codes to see if any are stored which will help us see what's going on.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Here is how to change out the BCM correctly. You can order a preprogrammed unit by searching eBay or Google. Check out the images (below). Please upload pictures or videos in your response to the problem so we can see what's going on.

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Saturday, March 23rd, 2024 AT 5:34 PM
Tiny
DTB0YZ86
  • MEMBER
  • 24 POSTS
I just replaced my battery a few weeks ago and the alternator is good. I ordered a new BCM from rockauto and it said it is plug n play no flash required but I'm worried it still will need to be programed. I'm going to the junk yard to pick up the three connectors cause the old ones are bad so when the new BCM gets here I will hook it up and do the relearn process with the key. Hopefully she starts up and it's actually plug n play like it says it is. I don't know.
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Saturday, March 23rd, 2024 AT 11:31 PM
Tiny
KEN L
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If the BCM needs programming, you will know because the security light will flash when trying to start it. Please let us know what happens.
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Sunday, March 24th, 2024 AT 10:38 AM
Tiny
DTB0YZ86
  • MEMBER
  • 24 POSTS
Does anyone know what the three connectors that go into the BCM are called? I can't find them online. I may just got to the junk yard and cut them off another grand am.
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Sunday, March 24th, 2024 AT 11:42 AM
Tiny
KEN L
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They are called "pigtail connectors" for the BCM, here is one with the BCM itself for $60.00:

https://www.ebay.com/itm/115896603255?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=115896603255&targetid=1645685074528&device=c&mktype=pla&googleloc=9031538&poi=&campaignid=20133407470&mkgroupid=147476396765&rlsatarget=pla-1645685074528&abcId=9312979&merchantid=101822193&gad_source=1&gclid=CjwKCAjwnv-vBhBdEiwABCYQA8aINUJ352AeU1R2-CkupkKy_hK1Jl_cqMw0rOSlIWq7NygUF09EfhoC66oQAvD_BwE

Let me know if this works, please.
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Sunday, March 24th, 2024 AT 2:31 PM
Tiny
DTB0YZ86
  • MEMBER
  • 24 POSTS
I already ordered a brand new one and it says its plug and play no flash required so hopefully that's the case, but I got the three pigtail connectors today and noticed when I cut my old ones off that there are multiple wires with the same colors on each connector. I really need a pin out diagram of the BCM and connectors to help me figure out what goes where. I don't know how I'm going to figure out which pink or light blue wire goes where since there's double on each connector.
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Sunday, March 24th, 2024 AT 9:19 PM
Tiny
DTB0YZ86
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  • 24 POSTS
Also, when I had my other BCM connected it threw u1000 code class 2 serial and a theft deterrent code. Plus, one of the pins on the BCM broke off and is stuck inside the old connector, I'm guessing because it was so corroded.
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Sunday, March 24th, 2024 AT 9:34 PM
Tiny
DTB0YZ86
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  • 24 POSTS
This is the old middle connector with the pin still stuck inside it. I was going to try to pull it out and solder it back on the BCM but just decided to buy a new one. Guess I'll find out if Rockauto was truthful about the new one being plug n play unless when I plug my old BCM back up with new connectors and it works.
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Sunday, March 24th, 2024 AT 9:40 PM
Tiny
DTB0YZ86
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I put the new connectors on it, and everything comes back on like normal, but it won't start. Doesn't crank or anything. Security light not blinking, and this is my original BCM.
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Monday, March 25th, 2024 AT 4:38 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
Here are the BCM wiring diagrams and a guide to help you check the wiring:

https://www.2carpros.com/articles/how-to-check-wiring

Check out the images (below). Please let us know what happens.
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Monday, March 25th, 2024 AT 8:55 AM
Tiny
DTB0YZ86
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B2948, P1626, U1000, and C1298.
These codes are coming up on my car.
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Monday, March 25th, 2024 AT 12:21 PM
Tiny
DTB0YZ86
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Could it be my ignition switch? There is a recall on it is think.
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Monday, March 25th, 2024 AT 1:08 PM
Tiny
KEN L
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Maybe, I would turn the key on and check for power at these fuses, here is a guide to help:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

You should have power at all of them. Check out the images (below). Let us know how it goes.

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Tuesday, March 26th, 2024 AT 9:19 AM
Tiny
DTB0YZ86
  • MEMBER
  • 24 POSTS
  • 2004 PONTIAC GRAND AM
  • 3.4L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 137,000 MILES
Ok, I recently had some issues with my BCM connectors being corroded causing weird problems like radio not working dome lights not working, car would just act funny. So I just got some others from the junk yard and hooked them up and now everything comes on except it won't crank. The security light is just solid Not flashing so does it still need to do the relearn process?
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Tuesday, March 26th, 2024 AT 9:48 AM (Merged)
Tiny
KEN L
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Yep, here is how the relearn process is done:

BODY CONTROL MODULE (BCM) PROGRAMMING/RPO CONFIGURATION

1. The body control module BCM must be programmed with the proper RPO configurations. The BCM stores the information regarding the vehicle options and if the BCM is not properly configured with the correct RPO codes, the BCM will not control all of the features properly. Ensure that the following conditions exist in order to prepare for BCM programming:
- The battery is fully charged.
- The ignition switch is in the ON position.
- The data link connector (DLC) is accessible.
- All disconnected modules and devices are reconnected before programming.
2. To setup a new BCM, access the SPECIAL FUNCTIONS menu on the scan tool to program the BCM. Select NEW BCM SETUP and follow the instructions on the scan tool.
3. If the BCM fails to accept the program, perform the following steps:
- Inspect all BCM connections.
- Verify that the scan tool has the latest software version.

Passlock Learn Procedures

IMPORTANT: If any module or device listed is replaced, programming of the module must be done prior to performing the Passlock Learn procedure.

Perform the Learn Procedure if any of the following components have been replaced:
- The body control module, BCM
- The Passlock sensor
- The powertrain control module PCM

IMPORTANT: After programming, perform the following to avoid future misdiagnosis:

1. Turn the ignition OFF for 10 seconds.
2. Connect the scan tool to the data link connector.
3. Turn the ignition ON with the engine OFF.
4. Use the scan tool in order to retrieve history DTCs from all modules.
5. Clear all history DTCs.

Please let us know what happens.
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Tuesday, March 26th, 2024 AT 9:50 AM
Tiny
DTB0YZ86
  • MEMBER
  • 24 POSTS
I didn't change the BCM just the connectors, my ignition has been acting up too. It has been sticking in the start position I need to check the ignition switch too. I don't need to reprogram it if I'm using the same BCM right? Just the keys relearn?
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Tuesday, March 26th, 2024 AT 5:14 PM
Tiny
KEN L
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That is correct.
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Wednesday, March 27th, 2024 AT 9:06 AM
Tiny
DTB0YZ86
  • MEMBER
  • 24 POSTS
I need the wire pin out of the BCM. I have the new bcm hooked up but my security light is on and I have codes coming up. Airbags and theft deterrent.
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Sunday, March 31st, 2024 AT 8:47 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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They are not giving the BCM pinouts on Alldata. You are going to have to use the BCM wiring diagrams above.
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Monday, April 1st, 2024 AT 7:24 PM

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