Help: Volvo 850 Automatic Transmission Problems

I recently purchased a 1996 Volvo 850 non-turbo as my sacrificial salt car for the winter. It will only upshift if you drive it like you stole it with your foot right to the firewall. It will not downshift when decelerating and there's an orange arrow flashing in the gauges all the time. I had the car at a dedicated Volvo shop to cure this. They replaced the TCM and both speed sensors. Now the car will shift perfectly if you let it sit overnight with the battery disconnected. But after three miles of driving, it goes back into the mode described above. A good friend of mine was the shop foreman at a volvo dealership when these cars were new. He told me to get an updated Servo cover to solve the problem. The only updated Servo covers I can find come from ipd, but they're only for the 2000+ models. Does anyone have any idea how to make this junk shift properly? I don't believe the transmission itself is bad because it shifts after the battery has been disconnected for a time.

My father had a 96 850. It's been a long time but I think that arrow means that the traction control is activated, which would probably mean that it wouldn't want to downshift.

So... I guess maybe you should see if someone pushed the traction control button first, but you may have a faulty sensor. Or, maybe you just have an accumulation of crud around the ABS stuff at the hub. Pull the wheels and make sure everything is clean around the toothed ring behind the hub.

Woody wrote: My father had a 96 850. It's been a long time but I think that arrow means that the traction control is activated, which would probably mean that it wouldn't want to downshift.

Sounds right to me and I think the TC should be controlled by the speed sensors. I believe you still have a sensor related problem, Sir.

In reply to N Sperlo:

Thank you. I believe it's sensor related as well.

You need to flash out the codes (If it has the AB connector under the hood), or get someone with a PROPER scanner to read the trans. The flashing upshift light means it is in limp mode, and something is dead. The part about it working correctly after resetting means the internal mechanical parts all work right.

The are prone to mode switch failure, but they usually work ok most of the time when that goes bad.

Streetwiseguy wrote: The part about it working correctly after resetting means the internal mechanical parts all work right.

This is my gut feeling, as well.

Any update on this car?

I'm curious as I may have found a deal on a 99 that's stuck in limp home mode.

My friend who used to be the shop foreman at a Volvo dealer says the problem is that the PNP switch I put in is the cheap Chinese one. He says replace it with the $200 OE Volvo part and the problem will go away. I'm just a little loathe to spend $200 on a $500 car, just on a lark.

I bet you could source a junkyard one for cheeeeeeeap. Any self service yards near you? Switches usually sell for $5 or something and those aren't a particular trouble spot.

I tried a used one but it didn't fix the problem either

I'm not sure this is any help, but we had similar issues with my g/f's '96 850 wagon back in the Spring. We threw a ton of parts at it (everything mentioned and more) and none fixed the problem. Eventually gave up and sent the car to a Volvo specialist. $3900 for a new transmission later and the car has been more or less ok.

Good luck. I feel your pain.

The flashing arrow is the upshift arrow. Has nothing to do with traction control. This light comes on when you are in the manual shift mode (not in D), and it's the way the cars computer indicates to you that it thinks you need to upshift.

So, I agree the problem is likely your PNP switch. Not that it's out of adjustment, just that it's likely gotten dirty in its contacts. This prevents the unit from fully knowing it is in D.

I wouldn't replace the switch myself, I'd simply take it off and clean it. This switch is accessable after you remove the air filter and battery tray. It's right there on the top of the transmission, under these parts.

Edit: (Since you posted apparently using a junkyard replacement switch) make sure the junkyard switch is clean and in good working order. Many times they are not.

An ebay tool you may find yourself wanting for this car is the FCR scan tool. You'll also need the software, but that can be found as a torrent. Makes diagnosing and resetting things on that car far easier.

In reply to foxtrapper:

I tried both a used switch, then a new Chinese one. I've changed it twice myself already. I'm not looking forward to a third time. Could it be out of adjustment or something? I have the proper scan tool & software, hence all the parts I've thrown at this piece of E36 M3!

There might be some useful information in this article:

http://volvospeed.com/volvo_repairs_how_tos/transmissions_driveshafts/pnp_switch_replacement.html

There is an adjustment for the PNP switch, and the link provided by Shawn will get it done for you.

If you've got the scan tool and software, what is it saying when you go into the transmission diagnostics?

Edit: Scratch that, I see the FCR doesn't read transmission codes on the 850.

Edit: Double scratch that. Check your OBDII codes, which you can do with a normal OBD code reader. The transmission shifter solenoid codes are read through OBD not FCR. See if you've got any stored.

There were two speed sensor codes. I replaced both speed sensors, to no avail.

Interesting. So we can rather reasonably rule out internal failure or such of the tranny. Instead, it seems there is something that is confusing it.

The later V70 and early 740 both used a kickdown cable, connected to the spool the throttle cable ends at. So I suspect the 850 used the same. If that cable gets hung, it could be constantly telling the transmission you're floored, which would keep it from upshifting normally. It could also be causing the indicator to tell you to upshift.

I'm a little confused by your description of downshifting. Are you saying once it finally upshifts to say 3rd, it won't downshift to 2nd?