1996 850R transmission. Stall or winter mode no codes

[nickm]

Hi All
Wondering if anyone could suggest a way of diagnosing this issue.

I have an intermittent stall or stuck in winter mode on a 1996 850R auto.
The issue is not temperature related it can happen from a cold or warm start and generally occurs in less than a minute into moving. It does not occur at idle.
The orange arrow will flash with the engine check and the car will stall. It always starts straight back up.
Or the trans will shift into winter mode and then disengage.
No faults are recorded. The arrow does not flash. I'm checking errors through Volfcr.
Trans fluid is good the cars drives well. The trans shifts fine when this is not occurring.

So far I have checked and cleaned the PNP The mode selector switch.

So could this be an ECU issue or possibly a solenoid issue....

Thanks Nick

[Clemens]

i fortunately haven't had to deal with my trannies too much (*knockonwood*), but if the switches are okay it could likely be a solenoid.
I know there is a way to test their resistance and i think you can also try to move them by putting the right voltage on the connectors. I remember a gentleman from switzerland with a t5r had a similar problem, it was the S2 solenoid if i recall correctly.
I doubt it is the ecu or the tcm, they are known to be very sturdy.
I hope someone smarter than me chimes in.

[bmdubya1198]

That's strange. Does your car have the little diagnostic code box in front of the ECU? Have you checked for codes on that? I'm not 100% sure the 850 still had that in '96, but if you do I would use it. It seems odd to me that the up arrow would be flashing yet you wouldn't have any transmission codes. Have you checked OBD2 codes?
Also, how does the ATF look? Is it clean or does it look dark or dirty?

[nickm]

thanks...Yes it is an odd issue.
My fluid is good. I flushed it 12 months ago when I changed the rear main seal. Levels are spot on.

1996 Australian R's have an OBD2 port in the console. But It runs motronic 4.3. so it is not fully OBD2 compliant.
so no under hood/bonnet diagnostic port.

Engine ECU , EEC and Cruse control codes can be read with on LED and a switch. The others can be read with VOLFCR.

I have looked through the Volvo trouble shooting guides. I can force a code by removing the Mode switch.

It seems the car will drop into winter mode and sometimes stall (not always). When it stalls the engine check light will flash up once. No code is stored.
It will come out of winter mode on its own after about 30 seconds . Or If I shut the car down and start it back up.
So I am suspecting a transmission fault causing the problem. It is difficult to trace or test the solenoids as the fault is intermittent and by the time it has occurred. I shut the car down to test the fault has gone.
But surely if solenoid S1 or S2 are failing it would show a code?
Do you know if the solenoids could cause a stall?
I am leaning toward changing the solenoids. But Avoiding it as it is a more complex job and may not solve the issue.

[Clemens]

are the solenoids that tough of a job? I thought they are accessile under the airbox/battery.
if you get a chance to get used ones from a junk yard it might be worth a try.

[bmdubya1198]

Usually if one of the solenoids fail, it will throw a code.
From what I've heard, I think one of them is easier and can be accessed through that panel on the front of the transmission under the battery tray, and the other is a bit more of a pain.
BUT, since you're not getting any codes and the car is stalling, I would check wiring. I had a huge thread and spent LOTS of time trying to figure out what was wrong with my car after I put it back together, and the transmission was in a failsafe mode, which felt like it was stuck in winter mode. However I didn't have the up arrow light at all, it just wouldn't work. After lots of dead ends, I eventually found that this gray square connector right near the purge valve under the air intake tube had been crushed. I put it back together and my transmission has worked perfectly ever since.
Check the wiring and connectors around the transmission, especially those connected to the PNP switch.

[nickm]

Yes I think I'll bite the bullet and change them.
I been over wiring and rebuilt the PNP in the process.

You need to either jack the engine or drop the subframe to get the front cover off for access to the S1 S2 solenoids.