Power Door Lock Help

[Boone83K10]

I have a unique problem with my truck. I searched the forum but did not see a problem similar to mine.

I have PW & PL. My windows work well. Both sides have new switches and everything has been lubed in the past 6 months.

My power door locks on the other hand. They unlock with no problem. But they are dead if you try to lock them with either switch. The switches have to be the original ones..they look awful.

I just ordered some new switches on Amazon Prime but if that doesn't fix it where should I look first. I have test light/multimeter and am not afraid of wiring.

I already have the wiring diagram for my truck. I see that both window/door lock wires run to the relay which says to me that it is fine since the windows work.

Any help is appreciated.

 

[RetroC10Sport]

Just went through this in my 1989 but mine doesn't have a relay which is odd. Bad switch. I'm going to go with a bad switch on your as well.

 

[robert8096]

I would start by checking for 12v at the connector of the PL motor. I can't remember if they work the same as the PW where the PW switch switches ground and positive voltage between the wires to make the window go up or down. Put the ground lead of the meter to ground and test to see if you have 12v on one of the wires at PL connection when locking then check the other wire when unlocking. Then place the ground of the meter in the PL connection and try it again. It should read a plus 12v one way (lock) and -12 the other way if it works like the PW. You can also do a continuity check on the switch with the meter.

 

[Boone83K10]

according to the schematic, the windows get power directly from fuse box and locks get theirs through the relay. Both are reverse polarity.

I am leaning towards the switch first then the actuator. how hard it is to get that sucker outta there?

 

[89Suburban]

The actuators aren't too bad to swap out imo.

Don't this make you wish you had 5 power door locks to troubleshoot like me?

 

[Boone83K10]

What gets me is neither actuator moves when you press either switch to lockand both work when you press unlock ...that seems odd to me

 

[RetroC10Sport]

Mine did that too. Well, the passenger side would move like a fraction of an inch.

 

[Boone83K10]

are the actuators riveted in?

 

[89Suburban]

They are bolted in, 7/16" socket should work.

 

[Boone83K10]

Ok. Will look at this on the weekend.

 

[chengny]

I find that this wiring diagram of the P/L circuit is a bit easier to read - also shows the guts of the relay better.

You must be registered for see images attach

For general info - a brief description of operation and diagnostic chart:

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images

You must be registered for see images

You must be registered for see images

how to capture screen

 

[Boone83K10]

Thanks Jerry.

Nothing on that diagnostic helps me with that both locks will unlock but not lock. Both switches work for unlock but not lock.

but it does point to the relay... great no junkyards here and you can't buy one.

 

[Boone83K10]

At least on the driver side it was the switch. put new switch in this afternoon and wham...locks and unlocks both sides.

 

[chengny]

how to capture screen

Thanks for the heads-up - downloaded and setup.

A lot of my data is in huge pdf files. To post an image requires extracting the page, editing it down to a reasonable size, converting it to a jpg and then heading over to the image hosting site for upload and only then can it be attached in a reply.

 

[chengny]

At least on the driver side it was the switch. put new switch in this afternoon and wham...locks and unlocks both sides.

I was almost going to suggest cutting the 194/195 leads and splicing them in reverse to see if it was the switch or the motor was weak in the downward direction. In the end I decide to bite my tongue and keep that idea to myself.