Rear window switch doesn't work

91BLAZER

MEMBER
1991 CHEVROLET BLAZER
15,600 MILES

Ok I have a 91 chevy s10 blazer that has all the optional accessories. Im not sure if im doing this correctly, but I know you put the car in park or neutral then you can use the button to open the back glass/hatch. I know the motor for the popping mech works because I stripped a wire and used a drill battery and it popped just fine. Used a test light on the switch and that worked. Is there something im doing wrong? Is the rear window popping mech tied in with something else, like the power locking doors? And is there a relay maybe that needs to be replaced. I dont think theres a relay but im just trying to eliminate small simple things. THANKS

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1 Reply

CARADIODOC

MECHANIC
33,873 POSTS

You're two steps ahead of most people. Sounds like the switch is working, and you know the solenoid is okay. That just leaves the wiring. If you connected your drill battery to a single wire in the solenoid's electrical connector, and the other terminal to the body, that proves the solenoid's ground wire is okay too. If the solenoid has a two-wire connector, you also have to look at the ground wire in the trucks harness.

Do the same test light test right at the solenoid connector in the back. My guess is it won't work there. That means there's most likely a broken wire going back there. You'll have to follow that wire and take voltage readings at any accessible test point to see where the voltage is lost.

It is possible there is a relay involved. You can tell by looking at how beefy the switch is and the size and color of the wires to it. If there's two large diameter wires, there may not be a relay. If the wires are small and none are the same color as those in back, there probably is a relay somewhere. Relays don't fail very often. Usually you'll find a corroded ground connection to the body or a broken wire.

Also, if the test light works in back at the connector, look at how the solenoid is grounded to the body. If it's through the tail gate hinges, that will show up as the test light lighting up on both wires in the connector when it is connected to the solenoid.