Help - Rear Barn Door Won't Lock On Suburban

[TurboDiverArt]

Hi All,

Hoping someone can point me in the correct direction. I just realized that the rear barn door on my Suburban won't lock. I don't hear it locking or unlocking with the remote. The other four doors do lock but not the passenger side barn door. The front 4 doors will be locked but the rear door will open. Additionally, I can have the factory alarm set on the truck and open the rear door and the alarm doesn

[TurboDiverArt]

No takers huh? OK, lets ask this then. Does anyone know or can lookup the wire color code for the rear barn door power lock? Maybe someone with a Helm manual for a newer Suburban, 1997-1999?? I assume there is probably 2 or three wires running to the door lock mechanism. Power/enable lock, power/enable unlock and maybe an always hot and/or ground. I'd like to assume that the grounding is probably done through the door but I've sort of learned never to assume anything with these trucks.

My game plan is that if I can determine which wires go to the contact switches in the door I can try and manually power them to see if the locking mechanism/motor is even working. If it is then I need to look forward in the wiring. I could also then check to see if that door contact gets power when I hit the lock/unlock.

If someone has a wiring diagram, knowing the schematic for the rear window defogger would kelp too. It's the passenger side rear barn door that's giving me trouble if it matters. 1999 Suburban K2500.

We’ll try to tackle why the dome light does not come on when I open either rear barn door later….

Art.

[markelectric]

Have you tried fiddling with the switch. Over time I have had to replace several on the side doors. I doubt that the rear switch is any different.

[gmenor]

There should be four or five plunger switches located on the upper right side of the pasenger doors. I've taken emory cloth and sanded them clean then applied di-electric compound on them and the door contacts.

[96ccdd]

There should be four or five plunger switches located on the upper right side of the pasenger doors. I've taken emory cloth and sanded them clean then applied di-electric compound on them and the door contacts.
I have also done the same thing on my 96, they are just contacts and cleaning them with an ink eraser or scotch pad should solve your problem.

Good luck
Mark

[DennisG01]

I had the same problem - unfortunately cleaning the contacts didn't work. It turned out to be the actual motor - it was sticking. I figured this out because when it wouldn't lock I would bang on the lock area from outside and all of a sudden I would hear it lock. I took the inner door panel off and sprayed what I could with WD-40. That has seemed to work for the past year.

As far as the defroster goes, I had that problem too. In that case, it was the plungers. One of them was stuck too far in and not making contact. I sanded down the side of the plunger so it was a little thinner. Do like the guys said above and try cleaning the contacts.

[TurboDiverArt]

I had the same problem - unfortunately cleaning the contacts didn't work. It turned out to be the actual motor - it was sticking. I figured this out because when it wouldn't lock I would bang on the lock area from outside and all of a sudden I would hear it lock. I took the inner door panel off and sprayed what I could with WD-40. That has seemed to work for the past year.

As far as the defroster goes, I had that problem too. In that case, it was the plungers. One of them was stuck too far in and not making contact. I sanded down the side of the plunger so it was a little thinner. Do like the guys said above and try cleaning the contacts.
I've tried cleaning the contacts and applying grease. Didn't solve either of the problems. The plungers seem to go in and out easily enough but I can clean the sides as well, makes sense.

I think I'm going to have to pull the door panel off and take a look at the wires and trace them back up to the contacts and check for voltage coming to the accompanying plunger. I can also directly supply voltage to the lock motor as well. Probably would also help me narrow down which one of the remaining contacts is to the defroster.

I was hoping someone had a wiring diagram to determine the hot leads for lock and unlock. I could then easily determine which plungers without having to pull the panel. Determining if power is being supplied would tell me if the problem is in the door or forward of the door.

Has anyone else received late email notifications? I see markelectric responded on the 15th but I only got the email notification last night at about 8:00pm. Got a bunch of them and one PM notification too.

Art.

[DennisG01]

Would this work:

Hold a voltmeter on the various plungers as someone else (or you with key fob) locks/unlocks the doors until you find the one with voltage. Just a thought...That would serve the purpose of at least finding out which side your problem is on (I think)

[TurboDiverArt]

Would this work:

Hold a voltmeter on the various plungers as someone else (or you with key fob) locks/unlocks the doors until you find the one with voltage. Just a thought...That would serve the purpose of at least finding out which side your problem is on (I think)
Yeah, that's what I'm planning to do when I get a weekend that's not raining or cold. If no voltage is found I'll have to pull the panel and trace wires and start to energize them to figure out which ones "should" be getting power. I'm hoping it's a simple connection problem but then again, problems are never that simple for me...

Thanks,
Art.

[diesel65]

Hi Art,
I got your PM....I was able to finally look at a Suburban at work.

Using a 12 volt testlight (easier than using a voltmeter), the first two contacts (#1&2) are for your defroster grid, to check, turn the ignition on (engine does not need to be running) and hit the defroster button (make sure the indicator lamp is on). Probe the two contacts and see if the tester lights up.

The second pair of contacts (#3&4 from the top) is for your door lock actuator, again connect the test light to the contacts and using the door lock switch on the rear pillar the light should light in either direction that you move the switch.

The last pin is the plunger for the dome light switch, the only way to check it to remove the entire contact assembly and check the wiring behind the switch. I've had one were the switch came apart and the dome light wouldn't work. There is two wires off this switch to control the dome light, To check and see if the dome light will go on and off without the switch, first unplug the switch, then short the two wires together and the dome light should come on. When you disconnect the two wires, do not be alarmed the dome light stayed on, that is your timer. If you want to see it go on and off instantly then leave the ignition switch on.

I have replaced alot of door actuators on Suburbans over the years, I have seen mostly the rear doors and a few of the barn doors.

Good Luck

I forgot to mention that the contacts are only brass tipped, so be aware how you probe with a testlight or a voltmeter so that you get a valid reading.

[TurboDiverArt]

Hi Art,
I got your PM....I was able to finally look at a Suburban at work.

Using a 12 volt testlight (easier than using a voltmeter), the first two contacts (#1&2) are for your defroster grid, to check, turn the ignition on (engine does not need to be running) and hit the defroster button (make sure the indicator lamp is on). Probe the two contacts and see if the tester lights up.

The second pair of contacts (#3&4 from the top) is for your door lock actuator, again connect the test light to the contacts and using the door lock switch on the rear pillar the light should light in either direction that you move the switch.

The last pin is the plunger for the dome light switch, the only way to check it to remove the entire contact assembly and check the wiring behind the switch. I've had one were the switch came apart and the dome light wouldn't work. There is two wires off this switch to control the dome light, To check and see if the dome light will go on and off without the switch, first unplug the switch, then short the two wires together and the dome light should come on. When you disconnect the two wires, do not be alarmed the dome light stayed on, that is your timer. If you want to see it go on and off instantly then leave the ignition switch on.

I have replaced alot of door actuators on Suburbans over the years, I have seen mostly the rear doors and a few of the barn doors.

Good Luck

I forgot to mention that the contacts are only brass tipped, so be aware how you probe with a testlight or a voltmeter so that you get a valid reading.
Thanks a bunch!!

With the door locks. How does two wired both lock and unlock? Does it reverse polarity or something?

Art.

[diesel65]

Yes, the door lock circuit works by reversing the polarity.
The actuators are small electric motors, almost like a Rack and Pinion steering.

[TurboDiverArt]

Thanks for the info.

I checked the door locks and rear defogger.

I get power across the two defogger terminals on the window that works but not the one that doesn't. I get no power on the door lock terminals when I hit the power lock. I think I need to pull off the contact plungers and test them from the rear to see if it