My 850 turbo is doing several bad sounding things. For starters, the arrow is flashing and it starts up in 2nd gear. If I put it in reverse, it goes forward!!! I have code 311 on A1, which is "RPM signal from transmission missing" according to bay 13. Does the car not go in reverse because it thinks the car's speed may be too high? Should I try replacing the speed sensor? My haynes manual covers that. I think the PNP switch is ok because I don't get the 313 code. How do I reset the flashing arrow? The switch was replaced at 80K, but now I'm at 140K.

If I get this working, I promise to finally flush the transmission.

From what I have been able to gather about the Neutral Safety Switch problems on the 850, the symptoms can be many and varied.
The "normal" code for PNP switch problems seems to be 313 in the A1 socket.
But,,, there are other codes that can occur as well. Mine consistently shows 322 but maybe when I replace the switch, I will get another code. I did not get a "classic" flashing up arrow as a warning. My car simply stopped going into reverse,no warning. However, once I tried to drive it a little ways, I got the flashing arrow. Ratcheting the shift lever did nothing.
I'm pretty much convinced that my problem is the PNP switch and I've ordered a new one, $80 from Groton. The problem may be something else but I figure that if I get a new code, I'll fix that.

I finally gave up and took mine to the transmission shop. I was able to see the transmission after teardown and the clutch plates were worn out and warped which provided enough engagement to make the car go forward when reverse was selected. It wasn't shifting into reverse because one of the hydraulic seal rings was out of position because the stub shaft it mounts on had worn away below the ring. I still don't have it back yet, but the bill will be about $2K.

"For starters, the arrow is flashing and it starts up in 2nd gear."

This is a classic PNP switch indicator...
--
96 850T, Bilstein HD, IPD swaybars

I have the same kind of problem, flashing up arrow, reverse doesn't work, starts off in winter mode. The code is 322 incorrect gear ratio. I've written to several Volvo boards and no one knows what the problem is. Ratcheting the shift lever several times doesn't help. A mechanic suggested a sticky or bad solenoid.
Tried Seafoam, didn't help
The 322 code might suggest that the PNP switch has slipped from alignment??

I'm seriously considering a manual swap.

Well for the 322 code here's a few things to check: Most of this stuff needs to be done at a shop, because the average owner won't have the tools needed. But this is the troubleshooting guide from the shop manual. There are a few simple things the owner can do though. Such as checking the fluid, cleaning the sensor contacts, etc....



Mike


DTC 322/P0730: GEAR RATIO INFORMATION INCORRECT -

1) Check transmission oil level. If oil level is low, top off
as necessary and check for leaks. Repair as necessary. If oil level is
okay, turn ignition on and check DTCs. Test drive vehicle while
observing automatic transmission warning light. If light begins to
flash note any unusual symptoms in transmission operation or function.
If transmission does not show any mechanical fault or malfunction, go
to next step. If transmission has a mechanical malfunction and DTC 322
is not reset, repair or replace transmission as necessary.

2) Turn ignition off. Connect measuring unit to TCM. Raise
and support front of vehicle. Turn A/C off. Idle engine. Set gear
selector to position "D" so front wheels begin to rotate. Increase and
keep engine speed at 2000 RPM. Set DVOM to Hz scale, then connect DVOM
between measuring unit terminals No. 1 and 2. If DVOM gives a stable
Hz reading when engine speed is constant and transmission is not
shifting, go to step 5). If Hz frequency reading shows wide
fluctuations, go to next step.

3) Ensure ignition is off. Disconnect TCM. Connect ohmmeter
between measuring unit terminals No. 1 and 2. If ohmmeter does not
read 300-600 ohms, go to next step. If ohmmeter reads 300-600 ohms,
ensure RPM sensor wiring is not located near sources of interference
such as electric motors or spark plugs.

4) Disconnect transaxle connector. Check TCM connector for
poor terminal contact. Repair as necessary. Reconnect transaxle
connector. Connect ohmmeter between measuring unit terminals No. 1 and
2. If ohmmeter reads about 300-600 ohms, DTC was set because of poor
contact in transaxle connector. If ohmmeter does not read about 300-
600 ohms, replace RPM sensor.

5) Connect DVOM (digital volt and ohm meter...) between measuring unit terminals No. 20 and 48. Shift transmission to "D" so front wheels begin to rotate.
Increase engine speed to 1800-2000 RPM. If DVOM displays a stable Hz
reading when engine speed is constant, go to step 8). If DVOM does not
display a stable Hz reading when engine speed is constant, go to next
step.

6) Replace VSS. Connect DVOM between measuring unit terminals
No. 20 and 48. Shift transmission to "D" so front wheels begin to
rotate. Increase engine speed to 1800-2000 RPM. If DVOM displays a
stable Hz reading when engine speed is constant, system is okay. If
DVOM does not display a stable Hz reading when engine speed is
constant, go to next step.

7) Ensure ignition is off. Ensure wiring between VSS and
instrument cluster is not located near sources of interference such as
electric motors or spark plugs. If wiring is okay, replace instrument
cluster. See appropriate INSTRUMENT PANELS article in ACCESSORIES &
EQUIPMENT.

8) Ensure ignition is off. Disconnect TCM. Connect ohmmeter
between measuring unit terminals No. 20 and 27 (solenoid S1), then
between measuring unit terminals No. 20 and 28 (solenoid S2). If
ohmmeter reads 10-15 ohms, go to next step. If ohmmeter does not read
10-15 ohms, check transaxle connector for poor terminal contact.
Repair as necessary.

9) Ensure ignition is off. Reconnect TCM. Turn ignition on.
Set gearshift selector to "D" position. Connect voltmeter between
measuring unit terminals No. 5 and 20. If voltmeter reads 0-.5 volt,
twist gear position sensor lever/shaft up, down, and to side. If
voltage reading remains constant, system is okay. If voltage reading
does not remain constant, go to next step.

10) Turn ignition off. Check gear position sensor adjustment.
Repair as necessary. See DTC 313: GEAR POSITION SENSOR SIGNAL
INCORRECT. If adjustment is okay, replace gear position sensor.
The DTC 313 is just the PNP switch adjustment. Set the emergency
brake. Adjust the PNP switch so that your reverse lights come on
correctly when you have the shifter in Reverse with the ignition ON.
That's all there is to it. :))

I've done a bit of work on it today, but no improvement. I flushed my fluid for starters. I also cleaned the main connector contacts and pulled out the RPM sensor out. The sensor had some chips and other gunk on it, so I wiped it off. Put it all back together, and no different except I noticed now I also have code 322. Not sure what parts to throw at it. I called the dealer and they were no help over the phone. Anyone have any ideas for the next step. I'm about to seek professional help, but I'm afraid of the answer.

Why are you waiting to flush the tranny? Do it now! Because R and D are so far apart on the selector lever, I too discount the PNP. At least disconnect the wires to the speed sensor and clean the contacts.

Klaus
--
(V♂LV♂s 1995 854T, 1998 V70R)

Could be the PnP again. Try rachetting the gear shift with the engine off about 20 times and see if things live again.
--
1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon. My cars have been running so well lately they've got me worried.

I've tried that, but no joy. I'm thinking it's not the pnp switch. I'm not seeing the failed backup lights or the 313 code.