Hello,
I have been having a very strange, very annoying problem with a 2005 Z71 Tahoe. The trouble started a few months ago when I noticed that one of the rear doors did not lock when I pressed the power lock button. I could see that the lock indicator slide lever was in the unlocked position. I worked the lock/unlock buttons a few times and it locked. This has happened intermittently several times since then on both rear doors but never the front doors. I had previously replaced both rear door lock actuator assemblies due to their door ajar switches being bad. Both parts were ACDelco OEM. I had never noticed any locking problems before replacing them. The new passenger side door lock actuator failed after a month and I replaced it with another under the part's warranty. Today, the intermittent lock issue continues on both doors. Fortunately, despite all of this trouble the door ajar switches, which were the reason for the assemblies replacement, function flawlessly. The obvious conclusion would be that the door actuator assemblies are of questionable quality. But here is where it gets confusing......
One day after opening the driver door with the key and entering the vehicle, I pressed the unlock button to unlock the door for a passenger to get in. The unlock button did nothing, no actuator noise, completely silent, none of the doors unlocked. I tried several more times with no success. After hitting the lock button and then hitting the unlock button the vehicle unlocked. This has happened several times as well, starting in the same time frame as the failure to lock issue. One time I even reached over to the passenger unlock button to make sure that the driver side unlock button was not defective and got the same result, no unlocking. This also happens intermittently.
Further more, I have noticed that when I exit the vehicle and lock the doors with the power lock switch, the security light will sometimes not turn on. It usually will blink till I close the door but it will occasionally not turn at all. Cycling the lock/unlock buttons will eventually make it blink line normal. Also, using the DIC I have selected for the doors to lock automatically when the vehicle is put into gear, as opposed to having the doors lock when the vehicle speed reaches a speed of +8MPH. However I can hear a noise, like the door actuators trying to lock, as I start to drive away. It sounds soft like they are trying to lock but can't. Again, this only happens intermittently.
Does the BCM interface with the DIC on the gauge cluster? This could explain the locking "in gear" vs "with speed" issue. A bad BCM might also explain the unlock buttons not always responding. I am still suspicious of both of the replaced rear door lock actuators being of poor quality. I am not sure how these are actuated since I don't have a wiring diagram. I did swap the lock/unlock relays in the drivers side fuse panel to see if any symptoms changed. Yesterday I removed the BCM and opened it up. I looked at all the solder joints and found nothing that looked suspicious. Maybe a bad ground is another possibility. I wish that I had a good wiring diagram to aid in troubleshooting. The vehicle is in great working order aside from this issue. Any ideas?
Thanks!
I have been having a very strange, very annoying problem with a 2005 Z71 Tahoe. The trouble started a few months ago when I noticed that one of the rear doors did not lock when I pressed the power lock button. I could see that the lock indicator slide lever was in the unlocked position. I worked the lock/unlock buttons a few times and it locked. This has happened intermittently several times since then on both rear doors but never the front doors. I had previously replaced both rear door lock actuator assemblies due to their door ajar switches being bad. Both parts were ACDelco OEM. I had never noticed any locking problems before replacing them. The new passenger side door lock actuator failed after a month and I replaced it with another under the part's warranty. Today, the intermittent lock issue continues on both doors. Fortunately, despite all of this trouble the door ajar switches, which were the reason for the assemblies replacement, function flawlessly. The obvious conclusion would be that the door actuator assemblies are of questionable quality. But here is where it gets confusing......
One day after opening the driver door with the key and entering the vehicle, I pressed the unlock button to unlock the door for a passenger to get in. The unlock button did nothing, no actuator noise, completely silent, none of the doors unlocked. I tried several more times with no success. After hitting the lock button and then hitting the unlock button the vehicle unlocked. This has happened several times as well, starting in the same time frame as the failure to lock issue. One time I even reached over to the passenger unlock button to make sure that the driver side unlock button was not defective and got the same result, no unlocking. This also happens intermittently.
Further more, I have noticed that when I exit the vehicle and lock the doors with the power lock switch, the security light will sometimes not turn on. It usually will blink till I close the door but it will occasionally not turn at all. Cycling the lock/unlock buttons will eventually make it blink line normal. Also, using the DIC I have selected for the doors to lock automatically when the vehicle is put into gear, as opposed to having the doors lock when the vehicle speed reaches a speed of +8MPH. However I can hear a noise, like the door actuators trying to lock, as I start to drive away. It sounds soft like they are trying to lock but can't. Again, this only happens intermittently.
Does the BCM interface with the DIC on the gauge cluster? This could explain the locking "in gear" vs "with speed" issue. A bad BCM might also explain the unlock buttons not always responding. I am still suspicious of both of the replaced rear door lock actuators being of poor quality. I am not sure how these are actuated since I don't have a wiring diagram. I did swap the lock/unlock relays in the drivers side fuse panel to see if any symptoms changed. Yesterday I removed the BCM and opened it up. I looked at all the solder joints and found nothing that looked suspicious. Maybe a bad ground is another possibility. I wish that I had a good wiring diagram to aid in troubleshooting. The vehicle is in great working order aside from this issue. Any ideas?
Thanks!
