To be clear this is a LIFTGATE model with the window inside the hatch like many SUVs. NOT the drop tailgate 2 piece. I have removed and tested the actuator and it works fine. Neither the rear button, the dash hatch button, nor the key fob releases the gate or the glass. It I hit the button and the relay under the hood in that fuse box titled "Rear hatch glass" clicks but no actuator movement. I had to buy a new relay because butterfingers dropped the original one into that no go space between the inner and outer fender so it's not the hatch glass relay. I can't find a relay for the rear hatch which has a separate actuator. I tried a new dash switch from my 2000 ZR2 and it's not the dash button. Is there a 2nd relay under the dash? Are their separate relays for the lift gate and the hatch glass? Am I wrong to assume that the clicking relay means the switch is getting power? Any suggestions or knowledge about this situation would be appreciated. I didn't even know they had a liftgate on the 4 door Blazers until I bought this one so my mutts could have windows in the summer.

 

I can help you with this but I need clarification on the set up. So you have a one piece liftgate rear "door" that hinges at the top with a latch release at the bottom on the cargo floor and a window in that "door" that releases separately on its own hinge with its own latch?

If I have that right, what does the keyfob release, the liftgate or the glass insert?

Same question for the dash button.

Same question for the button on the rear liftgate. Is that rear liftgate release a plain button or a combo key and button and does it actuate by pressing or turning the key?

George

 

I just bought it and I've never owned a liftgate blazer. I saw an actuator on the bottom release as well so I assume it also works off the dash button. My ZR2 doesn't have an actuator on the tail gate. It doesn't matter to me because I can open by the hand latch. It's the window I can't open without power.

 

There are two paths that can provide power to the liftglass latch motor in the liftgate to unlatch the liftglass. One uses the the liftglass relay. It gets power from the Mir/Lks fuse in the UHFB and the relay gets actuated by the BCM based on input from the keyfob or the dash button with some lockouts.

The second path also gets power from that same fuse but does not involve the liftglass relay. Instead that fused power goes to the lock cylinder switch in the liftgate but there is a lock out in the drivers door before that switched power goes to the lift glass release motor. Then there is the actuator ground and a few splice points along the way.

I would grab a multimeter and head back to the liftglass release motor and measure voltage from the blk/wht wire going into that unit with the meter ground on a clean point on the frame.(or better yet the battery ground post) and measure while pressing the keyfob, then the dash button and then the liftglass switch on the rear liftgate. Report back.

George

 

I did that yesterday when I had it apart. That's how I determined no power was getting sent back on both using the fob and the dash button. No power going back there at all according to the meter and a bulb. That was when I removed the actuator to make sure it wasn't the problem.

 

The hatch glass relay is new. If I push the hatch button the relay clicks so power must be getting to the hatch button on the dash. So I'm between the relay and the actuator by elimination I am thinking.

 

Do you have power at the actuator when you energize the liftgate lock cylinder switch? Where did you ground the meter?

George

 

There is no power going to the actuator. There is power going to the switch as I said the relay clicks. So between relay and actuator. It was properly grounded as I tested it on the light.

 

My question was an attempt to find where your problem is by cutting the possibilities in half for diagnosis. The rear liftgate lock cylinder method does not use the relay so that answer would have helped us find your problem. The relay clicking does not guarantee that it is working at full voltage under a load or that there is even power going to the relay contacts.


George

 

The liftgate uses and actuator so it must use a relay so where is it was my question? I did the diagnosis work to isolate the fault area. I was looking for someone who knows the system between the hatch button and if there is another relay in the system. Do you have any knowledge regarding that? Power is good to the hatch button and it's fine. The lift glass relay is new. The actuators work. So it's isolated. Is there an additional relay under the left side of the dash? Is there a specific wire I can send power through to make sure there isn't a fault in the hidden wiring. These are the problem areas. Do you have any knowledge to diagnosing that?