When I purchased my '91 745 turbo, I did not receive a key to the rear hatch.
I'm again having problems when I unlock drivers door all doors unlock except the rear hatch then on rare occasion it will actually unlock. The inside hatch release always works. I had this same issue on my '93 240 I solved by buying
a complete unit from a pick a part. In replacing this very complex locking system I observed just how complex it is. Must have been German Engineered. I was thinking it might be easier & less expensive to remove my faulty unit and replace key cylinder with one that actually has a key that works. Of course I'm open to any suggestions. email me at 1williamleland@gmail.com

The rear hatch does not have a separate key. The ignition key(master ) operates all locks, The valet key works all locks except the glove box and trunk on a sedan, and the glove box and cargo floor on a wagon

Bob, My original ignition key won't unlock hatch I never tried the glove box. I only received the ignition key no others. From postings of other lads on this site. It seems a new cylinder & key quite pricey.

I had an occasional locking malfunction on a '92 945T that was fixed by swapping the solenoid from a junker. Mine also had a completely corroded lock cylinder that crumbled in my hands when I took it apart to inspect it (very common here in the rust belt).

Get a tailgate rattle repair kit for when you go in to swap the solenoid.

Good luck!

I'm going to Kingman after Christmas where the '92 GLE 745 IS SITTING that I've been picking parts off of and I noticed on my last trip no one has yet disassembled hatch I think I remove EVERY PART STUFF CHEAP HERE.
It pains me the wrecking yards now crushing all 200 series Volvos.I'm looking to buy 745 WITH A BLOWN MOTOR THAT I CAN BUY CHEAP TRAILER HOME FOR MY OWN PICK A PART.

MY WIFE JUST LOVES THESE RWD VOLVO WAGONS, i NEED TO MAKE MY LIFE A BIT EASIER WITH MY OWN PICK A PART CAR AS VOLVO'S NOT LEAVING MY CARPORT any time soon

Good Plan there is a '92 745 GLE I've been picking it's bones for months now.

So, the rear hatch usually does not unlock via the electric/power door lock/unlock function, when using the key in the driver's door, is that right? But it does sometimes, when using that key in the driver's door?
And, that key does not work in the keyway in the hatch itself, is that right?
The key ought to be the same for that lock as for the others. Hmm; for sedans there was a 'valet' key, which would work in the doors and ignition but not trunk; it was the same pattern but a tad thicker. I don't know about that for wagons though.
Have you tried a different locking relay?

Jerry,
My owner's book for the wagon does show a valet key, although it was probably lost years ago. While it makes no difference if the valet key can't open the hatch lock, the glove box and spare tire compartment are probably still secure, if locked.
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1992 745 approaching 500k km

Jerry, You reiterated correctly. I don't think it is a electrical issue as I can ask my wife to operate drivers door lock while I'm at hatch there is activity but no unlocking. happening I was reading on the search area of this splendid website it seems there are a number of plastic clips that permit the arms to fall out.
I think I must remove carpet cover and peer into the dark abyss and hope it is some thing easy. thanks fot your input I'll post how I resolved issue.
Regards, Bill

In my opinion, it's a waste of time replacing the hatch lock cylinder if you live in the salt belt. (But I see you're in AZ.) When I bought my '92 745 three years ago, the lock wasn't working, yet the service records I received showed that it had been repaired and lubricated at least a couple times before. I tried injecting it with penetrating oil and cleaning it out to no avail. When I checked the price of a new lock cylinder and key, I think I saw something like $60 or $80 not including shipping - outrageous. Looking at the lock today, the plastic handle around it appears to be bulging from all the corrosion festering inside because the little flap in the keyhole got lost during one of my cleaning operations. I think the lock is a poor design, not protected enough from the elements in this area of the car. At least that's my rationale for not spending the bucks and devoting the time to do this job.
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1992 745 approaching 500k km

Old Yeller, I think this car took a light hit in the rear B-4 I came into the picture. perhaps a wrecking yard hatch was installed thus no matching key. I'm not up for $80 lock cylinders. I recently met a lad here in Bullhead City
that goes my the name of Volvo John, an old Vietnam Vet he called yesterday told me bring your wagon over let me look. I'll report the fix on BRICKBOARD.
BTW: Ol' Volvo John has no less than 6 Amazon's he is restoring Lustfull IMO
THANKS FOR YOUR INPUT REGARDS, BILL

Okay, I didn't catch on that the hatch wouldn't unlock by solenoid when you unlocked the driver's door. Mine does, so it's not a big deal that the lock cylinder doesn't work.
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1992 745 approaching 500k km

What do you mean you don't "get it"? If I operate the drivers door lock it often will not unlock the hatch & I do not have a key that fits the hatch lock.
Sure I can crawl back to the inside latch that always works but that really sucks when your wearing suit. and rear area has many items stacked in back. clear enough?
Bill

Re-read my last post. I said that I DO get it now, after seeing your second posting. I have a similar problem occasionally when the left passenger door lock knob doesn't come completely up when I unlock the driver's door. Maybe a weak solenoid or needs lubrication. Usually, after unloading stuff from the hatch, I'll lock the car by opening the left passenger door and pushing down the driver's lock button instead of getting my keys out again. Sometimes it won't open because the button isn't all the way up.
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1992 745 approaching 500k km

I had wife use button only this AM on drivers door then I used a straw and flooded the mechanism with 3 in 1 oil I think in view of my past experiences with this over engineered mechanism I'll add a prayer for a blessing. I'll post what Volvo John does. thx, Bill