Power door locks unlock but only driver will lock?

[Rocket Man]

Sorry if I sound frustrated. This problem really SUCKS. Let me explain it's actually quite simple whats happening but definitely not a valid mode for the BCM to command. The behavior is not listed in the manual either. I played with programming modes and set for all doors to lock & unlock but had no effect on my problem.

1. Command doors to unlock - all doors unlock.
2. Command doors to lock - only drive side door locks.

I cannot get the power locks to lock the doors. It only ever locks the driver side door.

Aha. I thought it was only the fob problem, didn’t realize the lock function wouldn’t work from any of the switches. Possible the master switch is bad, like mentioned. IIRC everything goes through that, I believe when I was working on my door panels and had the master switch unplugged the other switches didn’t work. So if the lock function on the master doesn’t work, I don’t think the lock function on the other 3 switches will work either. You might figure out which wires go to that switch and jumper them to see if you get lock.

 

[Danny3737]

Do you hear a noise/click at the other doors when you press the button on the key fob? Mine did the same thing, the fob and interior switch would lock the doors, but not unlock. My problem ended up being the actuators. Apparently they had enough power to lock, but not enough to unlock. Both my rear ones failed at the same time. I kind of doubt you had 3 fail at the exact same time. Hopefully yours is an easy fix.

 

[Matthew Jeschke]

I disconnected the BCM to see if behavior changed and it was the same. I then probed everything in the system down to this level. Blue highlighted lines are behaving fine...

It's kind of interesting, the switch just changes direction of current on lock motor. I cannot verify if the unlock is finding ground on it's own (could test)... Or if the motors are bad (I need to hookup a power source and try to command the locks directly.

Curious has anybody ever seen 4 of 5 lock motors fail at the same time?

 

[Matthew Jeschke]

Thanks Rocket Man & Danny3737 ~ I had wondered if the Master Swtich (driver side lock switch) was at fault. I disconnected the passenger with no change in behavior, however, I didn't tinker with the driver side.

Danny3737 interesting note on the power. I'll have to see if I can push power through the lines with my DC power supply and command a lock.

 

[drakon543]

unlikely that you have multiple locks fail simultaneously. without being there im still going with either the master control switches at the drivers door is faulty or you have lost a common neutral on the opposite side.

 

[Danny3737]

If you do have to replace any/all of the actuators, put a small amount of lithium grease at all the movable joints to keep them from binding up.

Thanks Rocket Man & Danny3737 ~ I had wondered if the Master Swtich (driver side lock switch) was at fault. I disconnected the passenger with no change in behavior, however, I didn't tinker with the driver side.

Danny3737 interesting note on the power. I'll have to see if I can push power through the lines with my DC power supply and command a lock.

 

[Matthew Jeschke]

unlikely that you have multiple locks fail simultaneously. without being there im still going with either the master control switches at the drivers door is faulty or you have lost a common neutral on the opposite side.

I quick disconnected the driver lock switch. The system performed the same. I thought this might have a master switch but doesn't look like it does?

I'm looking at the schematics everything is grounded through the post on the A-Pillar / Driver side SP203... I'm still trying to visualize how the reverse current works with the relays. That said, I tested all the relays and they seem to work fine (there's 3 of them).

 

[Matthew Jeschke]

I disconnected C6 & C4 from the Fuse Block (driver side instrument panel), C2 & C4 from the Instrument Panel Junction Block (Passenger side). Then I energized the lock actuators from those connectors. All 5 actuators performed normally. I noticed approximately 0.5 Amps at 12.5 V.

Both sides of the motor (lock & unlock) get current through them (according to test light) when I command the doors to unlock or lock.

Sigh... What is doing this :|

 

[Matthew Jeschke]

figured it out... *sigh* this is one anybody could EASILY mess up. I took apart my dash. Upon doing so I retaped all the harnesses and cleaned the junction / fuse blocks.

I had pulled the relays out of Fuse Block for the instrument panel, on the driver side.

There is a relay labeled jumper. The location in the block can be populated with a fuse or a relay. It's a fuse if you don't have power windows, and a relay if you do.

That relay can be installed backwards as the spot is not keyed. I had installed the relay backwards. Locks work perfectly now

Only took me about 4 hours to figure it out though :|

 

[Rocket Man]

figured it out... *sigh* this is one anybody could EASILY mess up. I took apart my dash. Upon doing so I retaped all the harnesses and cleaned the junction / fuse blocks.

I had pulled the relays out of Fuse Block for the instrument panel, on the driver side.

There is a relay labeled jumper. The location in the block can be populated with a fuse or a relay. It's a fuse if you don't have power windows, and a relay if you do.

That relay can be installed backwards as the spot is not keyed. I had installed the relay backwards. Locks work perfectly now

Only took me about 4 hours to figure it out though :|

You should have mentioned this critical information in your original post. If you had told me that you did anything related to a fuse box especially pulling all the relays out and reinstalling them, I would have told you to go back and check your work. It not only wasted your time, but others as well. Glad you figured it out.