Here's a weird hatch relase problem

[blepkowski]

So here's a weird one.

Why does my rear hatch release only work when the hatch is open?

When the hatch is open and I pull the switch the motor activates.

When the hatch is closed and I pull the switch not a thing happens.

The rear interior lights come on and off with the hatch opening/closing so the switch is good.

If I jump the hatch switch wires and shut the hatch ( to trick it into thinking its open) It pops the hatch like it should.

Something is definitely backwards here! Where should I be looking?

Thanks!

[Mrmerlin]

it sounds like the ground for the hatch motor is lost, trace the wires you should find a ground point in the PS rear corner of the hatch area ( behind the RT quarter cover a few screws and you should be able to bend it back enough to see the grounding point.
Also clean the hatch connections and all of the other wires that you can see.
Also check for an inline fuse and one at the CE panel inspect them if there are 2 the one in the CE panel is a 1 amp fuse, a 3 will work

[Alan in AZ]

Well you might try fixing the interior lights first since I presume they don't work from the door switches...

It seems everything else works correctly

Alan

[Alan in AZ]

Originally Posted by lfausty

ditto sounds like its working correctly just bound up in some direction the hatch lid is heavy on the mechanism the plte may need to come forward or back maybe not allen screwed down tight enough or to loose the mechanism when you switch seems like its trying allen screws may ned adj there too just too tight or loose to forward back , ?shocks on your hatch lid weak , the spring on the mechanism not decompressing all the way. the the hook part that catches when you close lid worn some ud have to adj allen screw plates top bottom and it wont be permanant everyone seems to agree that it has to be just right to get that opened closed without slamming shut or pushing down hard and turning key with other to open. and then it you get it and it shifts again over time

Err no - you misunderstand me & him - he says it works fine if he connects the hatch pin switch to ground... there seems to be no mechanical issue at all.

My point is the hatch works pefectly - its doing exactly what it should do there is no issue with it At ALL based on the description...

The issue is that the hatch release mechanism has an interlock with the interior lights. The intention is that you can only open the hatch when a door is open (so you can't release it while driving down the highway).

This is implemented via the door pin switches for the interior lights. So if the interior lights don't work from the pin switches - the hatch won't release. The fact that the hatch open causes it to work is only because the hatch also drives the interior lights.

Fix the door switched interior light mode and all will be fine. There is another workaround but this is the best way to do it.

Alan

[Mrmerlin]

Thanks Alan for clarifying the operation of the hatch

[blepkowski]

Just to make it more difficult, the interior lights and their switches ( both doors and hatch) operate perfectly.

[Alan in AZ]

Originally Posted by blepkowski

The rear interior lights come on and off with the hatch opening/closing so the switch is good.

What does this mean...? Does the hatch switch only operate the rear (hatch) lights - not the front roof light or door lights?

If thats what you mean that is not correct behaviour...and is the root of your problem

Alan

[blepkowski]

Originally Posted by Alan in AZ

What does this mean...? Does the hatch switch only operate the rear (hatch) lights - not the front roof light or door lights?

If thats what you mean that is not correct behaviour...and is the root of your problem

Alan

Yes only the lights for the hatch come on when the hatch is opened the roof/door lights remain off. That's not correct?



The motor does not struggle/ nor is it misaligned it works perfectly when the hatch is closed but with the hatch switch circuit is closed ( to think the hatch is open)
this is accomplished by jumping the plug for the hatch switch with a paper clip (the hatch lights also come on at this point).

[Alan in AZ]

Your lights don't work correctly - all interior lights should come on at the the same time.. this is the problem. There is a connector in the top of the hatch (near the lights) there is also a connector in the B-Pillar area near the rear passenger side speaker...

Alan

[Alan in AZ]

Originally Posted by lfausty

not to be difficult or have difficulties butttt dont start your topics weird theres nothing weird about solving a problemo weird passes all understandings of intelligent and knowledgeable people. theres only steps taken to help those who dont know how to or cant fix them themselves its kinda like saying this stupid hatch.

ohh difficult one maybe you should ask what the workaround method is my work around methods usually results in cutters in my hands and electrical tape , nothing crucial though lol

im just saying sounds like your entire system is working right maybe then the motor is struggling to hard to open motors motor going or mechanism is shifted so it cant open easyily enough.

if thats the case with doors relating to hatch safety i better get my wire strippers out cause im for sure getting pulled out of the vortex there. kidding but maybe u got the doors opened when your trying the switch to open hatch get all the way in and try and see if you here motor op too. nooo not that button i can fly ehhh haaa

Ehh - what !#@$%@!! Argghh!....

[blepkowski]

Ok so I want to make sure I'm clear here. Because my hatch switch does not trigger my door lights and vise versa. I have a bad connection somewhere?

Where are all of these signals terminating?

Does some type of brain figure out when to allow the hatch release to work?

Where should I start? Continuity or resistance checks? Starting where? Ending where?

Thanks!

[Alan in AZ]

There is no special brain - just what I said - check the connections.

Alan

[Fred111]

Resurrecting this as it’s similar to my problem. My difference is all of my lights come on together when the hatch is open. No lights come on with opening doors. Both pin switches seem ok. I cleaned them up just in case. My hatch release motor only runs with the hatch open. Can anyone point me to anything to check?

[Wet or Dry]

SO SO happy to have stumbled across this! I am dealing with nearly the same problem on my '88. Can't wait to dig in. I know my problem started with the overhead light mounted nearest the hinge of the hatch shorting out to the body because it was rotted in pieces. I just have to figure out where the current issue is since the fuse in the CE panel is ok. I will be looking in that B pillar for the connections there.

[Opelotus]

It just so happens that I am the current owner of the vehicle that blepkowski started this thread about (1984 928S).

I determined the car had 3 issues; interior lights didn't turn on when either door was opened. Alarm did not go off if armed and then either door was opened with the non-alarm key. And of course the hatch release motor was not activated unless the trunk was already open. Traced it back to the CE panel, where I found that connector F, terminal 5 had corroded, and the wires leading from the door pin switches into that connector had broken off. After repairing that connection, everything worked as it should.