Door lock actuators melting

[Eveready]

I'm pretty sure @someotherguy is on to something. Somehow a ground is being applied to the circuit, most likely a shorted wire. This is assuming that the actuator operates like everything else and has a constant hot wire which is triggered by being grounded by a momentary switch or relay. Good luck and report the fix!

 

[someotherguy]

Power locks are not fused circuit IIRC, they have a 30a circuit breaker in the under dash fuse block. If truck also has power windows, there are two of them.
I agree, something is getting shorted, to be melting parts.....

And those circuit breakers get DAMN hot before they'll trip - hot enough to melt your fingerprints if you just happen to try removing a breaker too close to when it reached the trip point. Been there, done that!! (on that same '94 Suburban) ..

Richard

 

[Bluekenworth]

Found the wiring diagram I was looking for and it’s a lot more complicated then i expected

The door actuator doesn’t have constant power waiting for a ground, power is only sent when a switch is hit

And the pwr accy circuit also run the powered driver’s seat along with the courtesy lights when a door is opened

maybe someone with a little more experience could point me in the right direction of where to look for shorts on the diagram

Also thinking about putting an inline fuse solely for the lock actuator until I can figure out the problem

 

[AK49BWL]

The motors have NO power applied until a switch is pressed. So the issue is very likely to be in the switch itself, OR if you have relays (with keyless you do have them) then one could be stuck on, and probably is. The motors DO NOT PULL ENOUGH CURRENT to trip the circuit breaker just from being on continuously! Testing on my truck (two doors) I only got a max of 8.6 amps continuous. That will fluctuate as the windings melt but by that time it's already too late.

 

[Bluekenworth]

The motors have NO power applied until a switch is pressed. So the issue is very likely to be in the switch itself, OR if you have relays (with keyless you do have them) then one could be stuck on, and probably is. The motors DO NOT PULL ENOUGH CURRENT to trip the circuit breaker just from being on continuously! Testing on my truck (two doors) I only got a max of 8.6 amps continuous. That will fluctuate as the windings melt but by that time it's already too late.

Each relay works like you would expect them to hooked up to a multi meter,

Going to change the lock relay and hope the relays on the bread board are ok,

I’m going to put an inline fuse before the actuator in the door, do I need to fuse both wires because each one will get a signal depending on the unlock or lock ?

 

[someotherguy]

I wonder if you disconnect the keyless entry module for a while, if the locks still operate correctly otherwise? It'd be interesting to see if it's causing the issue.

I'll agree the power lock setup on the Vortec-era trucks seems unnecessarily complex. When I was building my '94 3500HD project doing the whole newer engine and interior swap, for the sake of my sanity and time constraints I just left it crank window. That, and good power window door modules were a hot ticket for my customers - I was trying to build my truck out of parts my customers weren't buying, for various reasons.

Richard

 

[AK49BWL]

Each relay works like you would expect them to hooked up to a multi meter,

Going to change the lock relay and hope the relays on the bread board are ok,

I’m going to put an inline fuse before the actuator in the door, do I need to fuse both wires because each one will get a signal depending on the unlock or lock ?

You should only need one fuse, as the current will still flow on both sides regardless of which direction. Keep in mind the keyless entry controller module ALSO has relays inside. Four to be exact - 1: Driver unlock, 2: all others unlock, 3: all lock, and 4: the dome lighting.

I wonder if you disconnect the keyless entry module for a while, if the locks still operate correctly otherwise? It'd be interesting to see if it's causing the issue.

I'll agree the power lock setup on the Vortec-era trucks seems unnecessarily complex. When I was building my '94 3500HD project doing the whole newer engine and interior swap, for the sake of my sanity and time constraints I just left it crank window. That, and good power window door modules were a hot ticket for my customers - I was trying to build my truck out of parts my customers weren't buying, for various reasons.

Richard

My wiring diagrams indicate that the power locks system should be functional from the door lock switches without the keyless entry module installed. There will be no dome light control, however - they will only come on if the dimmer knob is in its dome override position, not with the door open switches.