Hi all, I have a '91 Z-28 that has a power rear latch. Mine does not open or close automatically, I have to hold the release button on the console until it releases fully, then to close I have to latch the lid, then hold the button on the console again till the hatch lowers fully. I was wondering if anyone else has this problem, or if anyone knew what to do about it. Thanks in advance for any help with this.

 

PM lonsal, he has the info and parts you need!, or try a quick search as this has been covered many times and the info is at your fingertips. Welcome to the jungle.

 

Thanks for the reply and info. I had searched already without much success, but with your suggestion I gave it another go trying some different wording. I found a post that had some helpful information in it here . I have a bit of troubleshooting to do now that I know how this thing works. I have only had the car for a few weeks. It looks like lonsal has most of the parts I would need to get it fixed. Thanks again for the help, its great to see this kind of support available for these manufacturer abandoned cool cars.

 

Hmmmm...well I took my rear latch assembly out to inspect/troubleshoot it. I fully expected to find a bad switch or something. I only found 2 switches on the assembly, one at the top, a black lever switch which seems to be good. On it I get good continuity during Normally Open and Normally closed states. the Black and BlackYellow wires seem to be Normally Open and the Black and BlackRed wires seem to be Normally Closed while the switch is in the up or hatch released position.

The second switch is mounted just above the motor and seems to toggle up and down with assembly movement. I also get good continuity with this switch while flipped up and down. Pin 5 on the connector seems common and is shorted to pin 4 while switch is up, and shorted to pin 3 while the switch is down.

I am assuming this is the newer style mechanism. it has kind of a tan casing which seems to be in good condition, no cracks or anything. What I dont see, or seem to be able to figure out, is how this thing knows the hatch has been closed to initiate the pulldown procedure. The black lever switch at the top seems to sit too low for the bar on the decklid to press on. I am a bit stumped for now. If anyone has some input it would be most welcome. thanks a bunch.

 

The first switch is a sensor that sends a signal to lower or raise the unit. The second switch you talk about is basically a reverse switch.

lonsal will definately be able to help you. Does it seem like the latch is bining anywhere?

 

There is a small black plastic piece that is attached to the back of the frame with two small 6mm hex-head screws. That plastic piece can be seen if you look from above. That plastic piece opens the latch when the pull-down unit reaches the top of the cycle. Check that yours has that piece.

Lon

 

Thanks everyone, yep that peice is there, it may require adjusting after some investigation...I have the thing working somewhat now, but it isnt quite rite. there was no power getting to the relay, I didnt check this at first because I figured there had to be power there since I could raise and lower the hatch with the button. After installing a missing fuse, when i hit the hatch button, the hatch raises, pulls back down somewhat then releases the hatch. when I go to close the hatch, the mechanism raises back up and stops. then I have to push down on the hatch again and it lowers and seals the hatch. This sounds like an adjustment to me? But before I go messing with it too much, I wanted to see what you all thought. Thanks a bunch for getting me this far, I expected to have to replace the entire mechanism at first.

I have another question regarding the interior while I'm at it. The pasenger floorboard carpet and insulation seem to be getting wet. I just had the A/C system repaired and converted to R134, the carpet doesnt smell moldy, so I think the moisture is semi fresh. I was wondering if there are any known issues causing wet floorboard on pasenger side, and if anyone knows where the drain tube from the A/C system is or should be. I must say, I have not noticed any wet spots under the car common with a good working A/C system.

 

does your windsheild fog up when you turn on your vents? if not i'm sure it will be soon, the heater core is right there in the passanger side dash, if you take off the lower hush panel, and look into the passanger side dash space, you will see a "black box" of sorts, thats where your heater core is.

Your heater core is leaking.


Its not that hard to replace just takes some time, search for heater core replacement.. YOU DO NOT have to take the dash off to get to it.

 

I will look into that, but it doesnt smell like antifreeze and I just checked my coolant level and it is good.

 

My leak didnt smell until the heater core desided to open up fully (ie: make a huge pool in my passanger foot well.

 

Mystery solved. I dropped the lower passenger dash cover to investigate the heater core area, there was no moisture or evidence of moisture in that area, however I did notice that the mook that owned the car before me, had ran a power wire (probably for an amp) through the firewall there, and did not grommet or seal the hole he drilled. there was discoloration around the hole. I am pretty posetive this is the source of the water, it has rained its **** off here the last week or 2. While I was in there, I sealed it with silicone, and also sealed around the edge of the connector behind the pasenger kick panel. Hopefully it wont take too long to dry out. The foam padding on the underside dash cover was dry as a bone, but the insulation backed rubber piece that lays against the firewall is soaked.

On a side note, I had my socket set in the rear of the car, and had to open the hatch to get to it. It worked flawlessly this time. Perhaps it just needed cycled a few times? I will give further report on how the hatch is working after I put the car back together later this evening. I went ahead and pulled the drivers side carpet back to inspect the floorboards there, all is clean and dry.

 

Good to hear it's working. I actually had a question. When you hit the hatch release, you say the mechanism raises and then releases the hatch? What mine does is when I hit the hatch release it will release the hatch from the bottom point and then the mechanism will raise. Just wondering whether that's correct or not

 

His is a 91-92 pull-down unit (having a tan plastic colred frame). That style won't release until it reaches the top of the cycle. Your 1986-91 style (easily distinguished by it having a metal frame) is very different. Yours (if equipped with the optional solenoid hatch release) can be rise immediately when popped IF you have strong hatch struts. The ONLY part that is compatible between the two styles is the gear nut.

Lon

 

I still have the issue with it raising up then going back down, it releases the hatch, but when I close it it raises back up and re-releases, then I push down on the hatch and it closes normally, it seems to be doing this about 8 of 10 trys.

 

Here's what's happening in your case: The pull-down switch operates differently in the down cycle compared to the up cycle. When cycling down the striker-sensing switch MUST be pressed the entire time. If mid-cycle it is released the motor will stop. It will not re-start until the switch is pressed again. This happens sometimes if the hatch hook is not latched, yet the hook presses the switch. In that case the unit powers down until the hatch seal is contacted, which lifts the hook off of the switch. The unit still hasn't fully cycled down. You won’t be able to latch the hatch now because the latch is already partially down. In that case the unit needs to be re-set. This is done by reaching in and pressing on the switch. The motor will start again and power the unit the rest of the way down. Once fully down you'll hear a loud CLICK which is the reversing switch being tripped ending the down-cycle. Now releasing the switch will cause the unit to cycle up. Here's the difference, pressing on the switch again WILL NOT shut off the motor. It will continue to power up regardless if the switch is pressed again or released until it reaches the top of the up-cycle. At that time you'll again hear a loud CLICK which is again the reversing switch being tripped.

In your case the hatch hook isn't raising far enough to clear the latch. When the unit cycles up the hook re-latches in the latch. Remember the unit will not shut off if this happens, it will just continue to power up. That is until it reaches the top of the up-cycle. Instantly your pull-down unit will start down again because the striker-sensing switch now is pressed, which tells it to cycle down.

There are a few ways to solve it. On a Camaro the solution is easier. Just install new hatch struts. When the solenoid or manual release is actuated the hatch should raise either fully or enough so the hatch hook clears the striker-sensing switch when it powers up. This is much harder to achieve on Firebirds with the HEAVY rear aero spoiler. You could swap that spoiler for the much lighter hollow fiberglass aftermarket one along with new hatch struts and the problem will be solved. Expensive solution, but it is a solution. Another way to solve it is to adjust the hatch pull-down unit either up or down slightly so the hatch hook keeps pressing on the striker-sensing switch once the hatch release button it pressed. It will take some time to get it adjusted just right, but it can be done. Once you've adjusted it as I describe you'll have enough time to walk around to the hatch and open the hatch. Be sure to mark the current location of the pull-down unit frame to the body with a permanent marker or scratch awl so you know where you started. The three holes that the bolts go through to mount the frame to the body are large square holes, so you can adjust the pull-down unit up/down and side to side. Just be sure that you keep the hatch hook properly aligned with the latch so it latches correctly and more importantly is correctly aligned to press on the striker-sensing switch. Also inspect the lever of the switch for wear. Sometimes they fail due to a circular groove being worn in the lever of the switch. Also inspect the pull-down unit for cracks where the 3 screws mount the clear plastic housing (called the motor housing) to the frame). If it is badly cracked or loose that will cause problems too.

Good luck,

Lon

 

I got it adjusted up, it was a little too high and a little off center. after a couple tweaks it is functioning normally now. Thanks alot for all of the advice lonsal and the others. Take care.