Power Door Locks weak

[JackE]

I'm working on a '99 2500 Suburban. My issue is when I push the power lock button, in the lock or unlock direction. I only get 3 of the 5 doors that will lock and unlock most of the time. I can see the passengers door lock moving about half way with either function. If I push the button 3-5 times to lock or unlock, the system acts like it is loosing power and will no longer lock any of the doors. I can still hear the locking relay clicking, just no power getting out to the actuators. If I wait about 5 minutes, it will work fine for 3-5 pushes again, then just relay clicking. I get the same results using the key fob. I have exchanged the lock relay, and the drivers side power lock button from my parts vehicle and have the same results. I did lube everything I could find related to the lock mechanisms in all 5 doors. I didn't expect it to help because of what seems like the lack of voltage to the actuators. Anyone with ideas?

 

[someotherguy]

In your lube efforts, did you pop the actuator rod from the interior manual lock knob to the latch - out of its plastic slider in the inner door skin - clean the lube off of it and re-apply? This stuff gums up over the years and makes the rod difficult to move; I've had several trucks where it made it feel like you were going to break the key off in the lock. Although it's the rod for the interior knob, it still has to move when the power locks (or the outside key tumbler) are operated.

Gently pop that rod out and clean it with brake parts cleaner sprayed onto a paper towel (don't spray it directly on the rod, you don't want that stuff messing up your window tint or any interior pieces nearby), also work that paper towel carefully through the plastic slider button...and then apply a little fresh lithium grease and re-assemble; work it a few times and see how it behaves. Also be sure you're working with the one for the lock, as the interior handle has a similar assembly.

Richard

 

[JackE]

Yup, I did that. I even unhooked all the linkage from the actuator on the worst door and tried it. I really feel like I'm dealing with a current flow issue. After I have pushed the lock button 5 or 6 times, there is nothing sounding like it's even trying to move, all I get is the relay clicking. If I push the lock button until it stops making the effort, I don't even get the effort if I push the unlock button. Just the relay clicking.

 

[east302]

The driver side of my 98 did that for a while. Outdoor temperature seemed to make a difference until it finally gave up. A new actuator solved the problem, but making sure that the actuator rods are greased and not bent up was a good first step. One quick test may be to just unhook the rod and see if it actuates. If not (and you have 12V to the actuator) then I’d swap it out.


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[Ken K]

Ok, Using GM electronic service info, your truck uses standard old school manual switches without serial data. The switch default to ground when released, then applies B+ to the door lock actuator depending on polarity for up or down. If you have a good Digital Multi Meter (DMM), go the the actuator and up plug. Carefully insert meter less to not damage connectors, but turn dial to DC voltage (If equipped with Capture / Record, use that also). Have a buddy push the lock switch either way and measure voltage. Your reading will be less than battery due to all of the connector, fuses, switch, etc. It should read the same as fuse box voltage. The actuator is a series circuit, designed to consume all of the voltage, so if plugged in, back-probe the motor, hit the switch and reading is now voltage drop across the device and should read fuse box voltage. If low, Check B+ (1 wire is hot depending one lock or un-lock) still fuse box B+. Check using a known good ground like "E" brake bracket and other wire at the motor. A good reading should be less than 0.500 volts. This is voltage drop. If higher (Say 1.2 volts) this would indicate switch contacts, connector condition (Clean with electrical cleaner, add Dielectric grease), but B+ wire in door jamb boot, connector inside to allow the door to be removed and both side of the circuit breaker. Remember, to turn the circuit on to draw current during test...Other wise you will not know if the circuit can handle the average required to operate and make the actuator's motor strong enough to handle the normal force required to function. Some testing, then back tracking will solve mystery. Just remember, that terminals inside plastic connectors can burn, turn colors, become spread and corrode, thus dielectric grease. Help this helps, but this is what we did in the dealer. There are several good vid's on voltage drop, but also found in section 8 or electrical service book with pictures & explanation of what you are seeing. Hope this make sense. Best of luck, but best practices.

 

[mars2878]

I'm working on a '99 2500 Suburban. My issue is when I push the power lock button, in the lock or unlock direction. I only get 3 of the 5 doors that will lock and unlock most of the time. I can see the passengers door lock moving about half way with either function. If I push the button 3-5 times to lock or unlock, the system acts like it is loosing power and will no longer lock any of the doors. I can still hear the locking relay clicking, just no power getting out to the actuators. If I wait about 5 minutes, it will work fine for 3-5 pushes again, then just relay clicking. I get the same results using the key fob. I have exchanged the lock relay, and the drivers side power lock button from my parts vehicle and have the same results. I did lube everything I could find related to the lock mechanisms in all 5 doors. I didn't expect it to help because of what seems like the lack of voltage to the actuators. Anyone with ideas?

any updates?

 

[JackE]

Nope. It got put on the back burner. I’ll order a new set of actuators and change all of them next spring. It’s too much like winter to be outside anymore.