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These are some Ign 1 power feeds to the BCM…with a Tech 2 you may be able to see this voltage…I believe it is under ACC/ELEC/THEFT…you can find data PIDS there.
Now as far as your airbag light the BCM supplies power through fuse 13 to the SDM module…power comes from run/crank Ign 1 which is the C4 connector pin C10 (pink wire)…looking at the B1001 the BCM when it is programmed stores the last 4 digits of the SDM module part number in it…a restraints ID relearn must be performed…this is under the BCM Programming/RPO configuration menu !!
Okay here's what I got
C3 connectorA3 12 volt reference 11.6 voltsA6-8 battery positive 11.6 voltsC2Bpp pin 18 getting 5.2voltsCar battery voltage drop is fine. Brand new Ultima batteryFuse 13 sDm okay
These are some Ign 1 power feeds to the BCM…with a Tech 2 you may be able to see this voltage…I believe it is under ACC/ELEC/THEFT…you can find data PIDS there.
To check the voltage drop across a relay which in this case is IGN1 Relay 44 the engine would be running and you would check from the positive side of the battery to a fuse which is downstream of that relay…ETC Fuse 9 is the one I’d check for so in your case check battery voltage and then check voltage at the fuse with the engine running and subtract the 2 readings…if battery voltage is 13.3 with engine running you should not see less than 13.0 at the fuse…max drop across a relay is normally 300mv or .3 volts…you could swap that relay out with the horn relay.
To check the voltage drop across a relay which in this case is IGN1 Relay 44 the engine would be running and you would check from the positive side of the battery to a fuse which is downstream of that relay…ETC Fuse 9 is the one I’d check for so in your case check battery voltage and then check voltage at the fuse with the engine running and subtract the 2 readings…if battery voltage is 13.3 with engine running you should not see less than 13.0 at the fuse…max drop across a relay is normally 300mv or .3 volts…you could swap that relay out with the horn relay.
Ok here's what I got. With engine running, battery is 13.95. From negative lead on battery and Fuse 9, I was getting 13.88. I tried swapping two different mini relays and got the same readings. Also just for fun, I checked the difference between battery positive terminal and the fuse block positive and there was no voltage drop. Is that VD from relay 44 a possible bad ground? I already took apart my fuse block and confirmed that I didn't have any breaks in the conductors and all the pins are firm.
Ok here's what I got. With engine running, battery is 13.95. From negative lead on battery and Fuse 9, I was getting 13.88. I tried swapping two different mini relays and got the same readings. Also just for fun, I checked the difference between battery positive terminal and the fuse block positive and there was no voltage drop. Is that VD from relay 44 a possible bad ground? I already took apart my fuse block and confirmed that I didn't have any breaks in the conductors and all the pins are firm.
Update: Fixed some issues by swapping old BCM back into car.
I swapped the original BCM back into the car since, like C5 Diag mentioned, it probably was fine and the dealership just blamed it since they couldn't find anything else.
Now the car doesn't wipe the memory every time you shut off the car, it must be some other circuit component of the BCM that is "special" on the 2005 LOL. So with that headache out of the way, I've discovered two issues: First I'm getting the C0161-12 DTC 5 volt reference to the BPP causing SAH light. I checked and I'm getting 4.1-4.3 volts at Pin 18 at C2 connector, I don't know what to do next since step 4 on the troubleshooting is "go to diagnostic aids." For fun, I tried calibrating BPP with Tech2. I get the error, "setup failed." did some googling and the only TSB I found was that the ECU needs to be reflashed first. So I tried that and still failing BPP setup. Also radio RPO setup keeps failing too. So Idk if this is all a step forward or backwards.
Last edited by the_slo_vette; Nov 19, 2022 at 03:31 PM.
