Lift gate and rear doors not working automatically
June 13th, 2023, 5:23 PM
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Lift gate and rear doors not working automatically
Hello! I'm new here and checking to see if someone had the same problem. Thank you!
My car is a 2005 Chevy Tahoe Z71. The lift gate locks, but do not unlock with remote or with door switches at the driver door. the 2 back doors will not lock or unlock with remote or with driver door switches, installed new relays for lock and unlock at the fuse box inside at driver side, checked all fuses, all are good and replaced the lift gate relay inside the passenger side B Pillar. Still will not unlock. New relay at B Pillar only actuate when locking the rear lift gate, but do not actuate when unlocking the lift gate. Put direct current to actuators and all work, they lock, then I switched the polarity, and they all also work unlocking, so actuators are all good. Tested the terminal cables at the actuators and all have constant negative coming out of both sides of the connectors. Tested both side of connectors of the back doors, using the remote control or switch at drivers door, and no positive came out. Tested both sides of the connector at the lift gate, and just one side activates positive using the remote control ot switch at driver door. Just in case this has anything to do with it, I just fixed the lights of the car, do to water coming in one of the rear tail lights. Everything was rusty and short-circuited, the lights were going crazy. Fixed everything, all lights are now in working condition, but the lock stills not working. One other thing I did was installing an after marked radio. But the doors were still working after the installation. The locks started intermittently, little by little not working till they finally stopped working 100% of the time.
I had to pull a Macgyver and remove the inside bottom half lift gate cover and tied a cord to the unlocking mechanisms so, I could pull it and unlock from driver side, because I don't have access when the back is full of my working tools. I just pray for the cord not to snap on me!
I need help!
Do I need a new BCU? Or a New electrical harness?
I guess I could disconnect the electrical harness to the lift gate and back doors at the plug inside the dash and test the terminals of the plug to see if I can get positive current. If I don't get any positive current when I press the switch at the door or the remote control, I will assume the problem is closer to the Body Control Unit and not the electrical harness to the doors.
Does someone know if the BCU has lock, unlock relays inside? I let you guy know what I find!
If anyone has any input, It would be greatly appreciated!! Thank you!
My car is a 2005 Chevy Tahoe Z71. The lift gate locks, but do not unlock with remote or with door switches at the driver door. the 2 back doors will not lock or unlock with remote or with driver door switches, installed new relays for lock and unlock at the fuse box inside at driver side, checked all fuses, all are good and replaced the lift gate relay inside the passenger side B Pillar. Still will not unlock. New relay at B Pillar only actuate when locking the rear lift gate, but do not actuate when unlocking the lift gate. Put direct current to actuators and all work, they lock, then I switched the polarity, and they all also work unlocking, so actuators are all good. Tested the terminal cables at the actuators and all have constant negative coming out of both sides of the connectors. Tested both side of connectors of the back doors, using the remote control or switch at drivers door, and no positive came out. Tested both sides of the connector at the lift gate, and just one side activates positive using the remote control ot switch at driver door. Just in case this has anything to do with it, I just fixed the lights of the car, do to water coming in one of the rear tail lights. Everything was rusty and short-circuited, the lights were going crazy. Fixed everything, all lights are now in working condition, but the lock stills not working. One other thing I did was installing an after marked radio. But the doors were still working after the installation. The locks started intermittently, little by little not working till they finally stopped working 100% of the time.
I had to pull a Macgyver and remove the inside bottom half lift gate cover and tied a cord to the unlocking mechanisms so, I could pull it and unlock from driver side, because I don't have access when the back is full of my working tools. I just pray for the cord not to snap on me!
I need help!
Do I need a new BCU? Or a New electrical harness?
I guess I could disconnect the electrical harness to the lift gate and back doors at the plug inside the dash and test the terminals of the plug to see if I can get positive current. If I don't get any positive current when I press the switch at the door or the remote control, I will assume the problem is closer to the Body Control Unit and not the electrical harness to the doors.
Does someone know if the BCU has lock, unlock relays inside? I let you guy know what I find!
If anyone has any input, It would be greatly appreciated!! Thank you!
Last edited by borumca; June 14th, 2023 at 1:25 PM. Reason: Grammar errors
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