My 850 came with 1 keyfob remote.

It sort of worked, but the tether that attached it to the keys was missing.

Through the generosity of another Volvo owner, I got a used but broken remote and was able to salvage the tether from it, moving it to my remote.

The fob now works, but not exactly as intended.

For example, if I hit unlock, it unlocks the drivers door maybe 20% of the time.

If I hit it again, it typically re-locks the door. Maybe 10% of the time, it unlocks the rest of the doors on the car.

I thought maybe the fob was faulty, so I found another one on eBay and bought it. The seller said it worked fine for him, and while I don't know him personally, he seemed honest and after doing some research, determined there are at least 2 different 850 fobs that look identical, and that the difference is likely the frequency that they operate at.

I tried to program it, using the ignition switch on/off 5 times within 10 seconds, starting the car, waiting for the alarm LED etc to flash. When I hit the button on the working remote, the LED reacts as the online instructions indicate it should. When I hit the button on the non-working remote, the LED is unaffected. It continues to flash - doesn't go out, stay on solid, or anything. Both remotes 'chirp' when you press the buttons.

I was told to look at the sticker on my working fob, but of course, after almost 20 years, there is no sticker or writing left on the back of the fob, it wore off.

Is there any way to determine what frequency fob I need? I imagine a new one from the dealer can get pretty expensive. Guess I could keep picking up whatever used fobs I can find a deal on, and hope I can get my $$ back out of them if I buy the wrong frequency?

I'd like 2 good ones when I'm done. Not sure if the problem with my fob is the fob or something in the car that needs adjusted/replaced/etc. Can't tell how I'd know unless I got another fob that works with the car.

Any ideas, tips/tricks/troubleshooting steps/links are much appreciated!

 

If the FCC id number is worn off the good one the only way I know of is to pull out the glove box to get the number off the unit itself.

You might try the dealer with your VIN handy, I didn't try that.

You also want to go to an auto parts store like oreilly, autozone ... to have your transmitter checked. They have a unit where you can check for free if your transmitter is transmitting. Make sure it's working before you go through a lot of trouble trying to sync it with the car or taking the car apart to find out why it won't.

If an ad for a remote shows up at the bottom when you view the picture, that's not from me and I have no idea who they are or if they are reliable.

 

It sounds to me like the thread opener has the guard system, because normally the LED will not flash when you try to "learn" a standard fob (the one with lock and unlock buttons separately).
The Guard relay is under the dash in the 2nd row and has a green connector on top.

 

My remote is the variety with 2 buttons, one on top of each other, not side by side.

 

I see yours is a 97 model. In this year the 850 had also a red relay for the central locking which aknowledges closing and opening with the turn lights. The fob looks identical to the Guard II system (I think they're the same actually).
Either way on the relay a PN should be present which gives you a clue for which market the system was build.

 

From what you are saying do 3 door locks work properly and only the drivers door is having issues or is it all of them?

 

So, I pulled out the glove box liner - and surprise, no module on the right side behind the liner.

Might it be anywhere else?

The problem I have... I can press the shared lock/unlock button and it just locks.. and locks... and locks. It has to be pressed a good 10 times before it unlocks once.

It never, or next to never, will let me unlock a second time to unlock the other doors and tailgate. If you hit the button the 2nd time to make it unlock the rest of the doors, it just locks everything, drivers door included.

 

Anyone know where the keyless entry receiver on a '97 850 is ??
Pretty clear I don't
Sorry about that, can't imagine they'd have moved it.

I've had the same problem with mine. Mine didn't come with remotes. I found the unit and the code so ordered two new ones off ebay. Fought to get them synched. Tried the key on off, tried with drvs door locked from outside, rear lock locked and reached in to operate ign. I tried so many different combinations I forget what worked. Now they still seem a little intermittent. Sometimes they will lock and unlock, other times only lock or only unlock. Can't get a grip on what makes it freak out.
My 5th door power lock actuator isn't working so I think it has something to do with my problem but haven't had a chance to rig a new actuator to it yet. Trying to find the thread someone posted on how to do it and what actuator they used.

 

I wrote in a previous post that the receiver is a relay unterneath the dash. Take out the dash cover on the drivers side. Then you will see 3 big connectors when you look up. These 3 connectors are all together on a metal plate. The plate itself is hold my two bolts with 10 head, you only need to loosen them a little. The plate can be unhinged then and you have full access to the relais.
The relay you are searching is in the 2nd row counting from the lowest, in the middle and has a green 5 pin connector on top.
If the relay is black than you have the Guard II alarm relay, if it's pink or red it's just the receiver.
The remote receiver looks like in the pic, the Guard looks the same but is black.