Is my BCM hurt?
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Joined: Sep 2005
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From: Murphy TX
Is my BCM hurt?
I had my AC evaporator drain back up and a large amount of water drained into the car. I let everything dry out, and now I can't get the car to crank.
I have quite a few codes, including B0432, B0503, B0508, B2483, B2527, B2588, B2593, B2723.
In addition, the horn doesn't honk when I hit the lock button on the remote, and the trunk release doesn't work from either the remote or the button on the dash.
I got out the meter and checked continuity from both grounds on the BCM to the battery, they seem ok.
I triggered the horn relay by grounding the pin in the wiring harness at the BCM connector and the horn sounds.
I was able to pop the trunk using the same method as above.
All static and switched power supplies to the BCM have the proper voltage in the proper conditions.
Anything else I should check, or go ahead and buy a new (to me) BCM?
TIA!
I have quite a few codes, including B0432, B0503, B0508, B2483, B2527, B2588, B2593, B2723.
In addition, the horn doesn't honk when I hit the lock button on the remote, and the trunk release doesn't work from either the remote or the button on the dash.
I got out the meter and checked continuity from both grounds on the BCM to the battery, they seem ok.
I triggered the horn relay by grounding the pin in the wiring harness at the BCM connector and the horn sounds.
I was able to pop the trunk using the same method as above.
All static and switched power supplies to the BCM have the proper voltage in the proper conditions.
Anything else I should check, or go ahead and buy a new (to me) BCM?
TIA!
Tech Contributor
Joined: Jan 2007
Posts: 19,422
Likes: 1,146
From: Dyer, IN
I had my AC evaporator drain back up and a large amount of water drained into the car. I let everything dry out, and now I can't get the car to crank.
I have quite a few codes, including B0432, B0503, B0508, B2483, B2527, B2588, B2593, B2723.
In addition, the horn doesn't honk when I hit the lock button on the remote, and the trunk release doesn't work from either the remote or the button on the dash.
I got out the meter and checked continuity from both grounds on the BCM to the battery, they seem ok.
I triggered the horn relay by grounding the pin in the wiring harness at the BCM connector and the horn sounds.
I was able to pop the trunk using the same method as above.
All static and switched power supplies to the BCM have the proper voltage in the proper conditions.
Anything else I should check, or go ahead and buy a new (to me) BCM?
TIA!
I have quite a few codes, including B0432, B0503, B0508, B2483, B2527, B2588, B2593, B2723.
In addition, the horn doesn't honk when I hit the lock button on the remote, and the trunk release doesn't work from either the remote or the button on the dash.
I got out the meter and checked continuity from both grounds on the BCM to the battery, they seem ok.
I triggered the horn relay by grounding the pin in the wiring harness at the BCM connector and the horn sounds.
I was able to pop the trunk using the same method as above.
All static and switched power supplies to the BCM have the proper voltage in the proper conditions.
Anything else I should check, or go ahead and buy a new (to me) BCM?
TIA!
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Joined: Sep 2005
Posts: 593
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From: Murphy TX
Tech Contributor
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Make sure that the battery is properly charged. Blow out the BCM with compressed air , clear the DTCs and see what DTCs come back. Report those.
BC
BC
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From: Murphy TX
Thread Starter
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Joined: Sep 2005
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From: Murphy TX
I got most of them to go away, still have b2527 and b2723 both h and c.
Still no start, no crank. Car will lock and unlock with the remote now, but again no horn. I didn't try to ground the horn relay wire at the bcm again but I assume that i can still get the horn to come on by doing that.
Still no start, no crank. Car will lock and unlock with the remote now, but again no horn. I didn't try to ground the horn relay wire at the bcm again but I assume that i can still get the horn to come on by doing that.
Tech Contributor
Joined: Jan 2007
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From: Dyer, IN
How?
It's not going to, as long as the B2723 is current. I would inspect BCM connector C1, as the input for the Pass Key detection, and horn relay circuit go to that connector. If the connector looks good, you could check for the key resistance value across pins A3 & B2. Also inspect the receptacle side of the BCM connector C1 for corrosion, moisture, etc.
It's not going to, as long as the B2723 is current. I would inspect BCM connector C1, as the input for the Pass Key detection, and horn relay circuit go to that connector. If the connector looks good, you could check for the key resistance value across pins A3 & B2. Also inspect the receptacle side of the BCM connector C1 for corrosion, moisture, etc.
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From: Murphy TX
I charged the battery, then disconnected it. I took the BCM out of the car, and took it out of the metal box. I took compressed air and blew out the connectors, and under the ICs on the board (well as far under them I could get. I then reassembled the BCM into the metal box, put it back in the car, and reconnected the battery. I put the key into the ignition and attempted to start it, no dice. I removed the key and reinserted it and then pulled codes, and the ones that I posted are what I got.
Thanks for the great info here, I'll check out C1 and verify that I get the key resistance value across A3 and B2 with the key inserted into the ignition cylinder. I plan to try first accessing the back side of the connector (where wires enter - will PROBABLY get something different depending on how the internals of the BCM are done), and also by disconnecting C1 and measuring at the BCM side of the connector. Of course I will do this with the battery disconnected.
It's not going to, as long as the B2723 is current. I would inspect BCM connector C1, as the input for the Pass Key detection, and horn relay circuit go to that connector. If the connector looks good, you could check for the key resistance value across pins A3 & B2. Also inspect the receptacle side of the BCM connector C1 for corrosion, moisture, etc.
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From: Murphy TX
I get 11.7 kOhm across both the key pellet as well as A3 and B2 when I measure across the terminals of those two pins on C1. During this second test the key is inserted in the ignition cylinder, battery disconnected and connector C1 disconnected from the BCM.
With BCM reconnected, battery reconnected and key in the ignition I read 0V on B2 and 5.92V or so on A3.
I did not notice any condensation or corrosion on either the bcm or the connector for C1.
Is it possible that the BCM forgot the effective resistance value in the key resistor pellet and needs to relearn?
With BCM reconnected, battery reconnected and key in the ignition I read 0V on B2 and 5.92V or so on A3.
I did not notice any condensation or corrosion on either the bcm or the connector for C1.
Is it possible that the BCM forgot the effective resistance value in the key resistor pellet and needs to relearn?
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Joined: Jan 2007
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From: Dyer, IN
I get 11.7 kOhm across both the key pellet as well as A3 and B2 when I measure across the terminals of those two pins on C1. During this second test the key is inserted in the ignition cylinder, battery disconnected and connector C1 disconnected from the BCM.
With BCM reconnected, battery reconnected and key in the ignition I read 0V on B2 and 5.92V or so on A3.
I did not notice any condensation or corrosion on either the bcm or the connector for C1.
Is it possible that the BCM forgot the effective resistance value in the key resistor pellet and needs to relearn?
With BCM reconnected, battery reconnected and key in the ignition I read 0V on B2 and 5.92V or so on A3.
I did not notice any condensation or corrosion on either the bcm or the connector for C1.
Is it possible that the BCM forgot the effective resistance value in the key resistor pellet and needs to relearn?
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Joined: Sep 2005
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From: Murphy TX
Curiouser and curiouser. I was never able to get past step 4 in the 30 minute relearn procedure. Even after 12-15 minutes the security light never went out.
I would stick the key in the ignition, attempt to start the car, then release the key, making sure not to turn the key to the off position. I would then wait for the security light to turn off, which it never did in the 12-15 min that I waited.
Fwiw, I noticed in the past that there would sometimes be a lag between turning the key to the ignition position and the car starting, sometimes a few seconds.
I would stick the key in the ignition, attempt to start the car, then release the key, making sure not to turn the key to the off position. I would then wait for the security light to turn off, which it never did in the 12-15 min that I waited.
Fwiw, I noticed in the past that there would sometimes be a lag between turning the key to the ignition position and the car starting, sometimes a few seconds.
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From: Murphy TX
Good news and bad news....
The good news is that I got the car to start. The bad news is that I had to do some interesting things to make it happen.
I took apart the BCM and studied it carefully, only to find this:
Looks like some input devices got fried... I think they're capacitors, not sure though.
I discovered that I could get the car to crank by grounding pin B7 on connector C3. Unfortunately, it wouldn't stay running because the BCM wasn't communicating via serial communication to the PCM that the fuel pump should stay running.
I scratched my head for a bit, then got an 'aha'!
I whipped out my copy of hptuners and what do you know, there was an option to turn VATS off. I did this, uploaded the new calibration, grounded B7 on C3 again, and voila! The car starts and runs!
I need to buy a new BCM, but in the interim I am going to wire in a momentary pushbutton switch to let the ignition actuate the starter.
Anyway, I thought everyone here might be interested in what I had to do to make the car go, so I'm reporting back.
The good news is that I got the car to start. The bad news is that I had to do some interesting things to make it happen.
I took apart the BCM and studied it carefully, only to find this:
Looks like some input devices got fried... I think they're capacitors, not sure though.
I discovered that I could get the car to crank by grounding pin B7 on connector C3. Unfortunately, it wouldn't stay running because the BCM wasn't communicating via serial communication to the PCM that the fuel pump should stay running.
I scratched my head for a bit, then got an 'aha'!
I whipped out my copy of hptuners and what do you know, there was an option to turn VATS off. I did this, uploaded the new calibration, grounded B7 on C3 again, and voila! The car starts and runs!
I need to buy a new BCM, but in the interim I am going to wire in a momentary pushbutton switch to let the ignition actuate the starter.
Anyway, I thought everyone here might be interested in what I had to do to make the car go, so I'm reporting back.
Tech Contributor
Joined: Jan 2007
Posts: 19,422
Likes: 1,146
From: Dyer, IN
Good news and bad news....
The good news is that I got the car to start. The bad news is that I had to do some interesting things to make it happen.
I took apart the BCM and studied it carefully, only to find this:
Looks like some input devices got fried... I think they're capacitors, not sure though.
I discovered that I could get the car to crank by grounding pin B7 on connector C3. Unfortunately, it wouldn't stay running because the BCM wasn't communicating via serial communication to the PCM that the fuel pump should stay running.
I scratched my head for a bit, then got an 'aha'!
I whipped out my copy of hptuners and what do you know, there was an option to turn VATS off. I did this, uploaded the new calibration, grounded B7 on C3 again, and voila! The car starts and runs!
I need to buy a new BCM, but in the interim I am going to wire in a momentary pushbutton switch to let the ignition actuate the starter.
Anyway, I thought everyone here might be interested in what I had to do to make the car go, so I'm reporting back.
The good news is that I got the car to start. The bad news is that I had to do some interesting things to make it happen.
I took apart the BCM and studied it carefully, only to find this:
Looks like some input devices got fried... I think they're capacitors, not sure though.
I discovered that I could get the car to crank by grounding pin B7 on connector C3. Unfortunately, it wouldn't stay running because the BCM wasn't communicating via serial communication to the PCM that the fuel pump should stay running.
I scratched my head for a bit, then got an 'aha'!
I whipped out my copy of hptuners and what do you know, there was an option to turn VATS off. I did this, uploaded the new calibration, grounded B7 on C3 again, and voila! The car starts and runs!
I need to buy a new BCM, but in the interim I am going to wire in a momentary pushbutton switch to let the ignition actuate the starter.
Anyway, I thought everyone here might be interested in what I had to do to make the car go, so I'm reporting back.
Melting Slicks
Joined: Oct 2007
Posts: 2,383
Likes: 13
From: Kinston North Carolina
This is just a WAG, but if what I'm seeing is just contamination from the water, it can probably be cleaned with a tooth brush and alcohol. If the components are FRIED, no such luck. Might be worth a try. Good luck.
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I took a little break while I was typing, so Lucky beat me to it, but I certainly agree with him.
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I took a little break while I was typing, so Lucky beat me to it, but I certainly agree with him.
Last edited by byronhunter; Sep 17, 2010 at 11:30 PM.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Thats the CLASSIC corrosion that happens after repeated water soakings of the BCM. Just scrub it off with a soft bristle brush and alcohol. Carefully inspect the components (USE A LUPE) and make sure that its making proper contact.
I had the exact same issue with my 98 Coupe and cleaned and restored normal operation. IF,,, you have corrosion there, you better be looking the board over for more. Especially under components.
Clean it well and give it a try.
OH,,,,,, Solve that water leakage issue before you get more damage
BC
I had the exact same issue with my 98 Coupe and cleaned and restored normal operation. IF,,, you have corrosion there, you better be looking the board over for more. Especially under components.
Clean it well and give it a try.
OH,,,,,, Solve that water leakage issue before you get more damage
BC
