I just had the PNP switch replaced in my 1993 850 glt. Picked it up from the shop and the car shifted fine until I had been driving it for more than 15 minutes. That's when the car fails to shift properly and the up arrow starts flashing.

I took it back and the guy said he "made an adjustment to the PNP switch." When I picked it up, the same thing happened, starts out fine, then kinda goes into limp mode when the car gets hot (also seems to be a strong odor of antifreeze when this happens).

I took it back again and the guy says he got a vehicle speed sensor code. Says that could be the problem and will run me about $150.

I'm confused and have no idea what it could be or what do to do. Any help is appreciated...

 

Hello mtoerner,

Greetings from Yokohama, Japan.

I have a feeling that the guy is trying to wring you out of $$$, though I'm not 100% sure. I'm not sure if the PNP switch is even adjustable.

First, try resetting the ECU → http://volvospeed.com/Repair/a1.html

Second, visually inspect the colour of the coolant in the expansion reservoir when the engine is cold. It should be clear green (in general. Some coolant use different colours such as red, yellow or blue). If it looks darker, the radiator may have a leak for transmission fluid and mixing with coolant.

Then, inspect the transmission fluid, by pulling out the dipstick, which is kind of hidden but you'll find it to the right of the engine compartment, close to the radiator. It should have an yellow top. Pull it out and check the colour, it should be clear red and should not have burnt smell. If cloudy, the situation is the same as above.

Next, check the transmission fluid level. Drive the car for about 15 minutes and then apply parking brake fully, and with your foot on the brake pedal firmly, shift through ALL detentes, pausing at eachdetent for 2-3- seconds. I mean, shift from P-R-N-D-3-L, then L-3-D-N-R-P. Leaving the engine idling and parking brake fully applied (and wheel chocks if available), open the hood, pull out the transmission dipstick, wipe clean with lint-free cloth or paper towel and re-insert it fully, making sure that there is no foreign object on the dipstick. Pull it out again and check the fluid level, it should be within "HOT" mark.

I have a feeling that your tranny is low on fluid. Low fluid can turn on the flashing arrow and can put the car into limp mode. I once had this problem, and it was caused by low fluid, by as little as a half quart.

Some helpful resource:
http://volvospeed.com/Repair/pnpswitch.php

Try getting a 2nd opinion, preferably from a Volvo dealer or a shop that specialises in Swedish/European makes (if the first place was a dealer, try another dealer) and see if they tell you the same thing. But you can check codes by yourself, since your 850 is of '93. Do a bit of search in this section of the forum, and you'll find the procedure for retrieving codes.

I hope this helps.


JPN

 

The PNP switch can be adjusted, but typically the symptoms to that are the car not being in drive when the gear selector is in drive or some other gear.

 

Update...

the guy says my transmission is toast.

it's weird though, the car seems to shift fine when it's cool, but it gets worse when the car gets hot.

I may take it to one more place before I drop $2,000+ on a tranny.

Any other things I could check out?

 

I'd try getting the tranny flushed if it hasn't been done recently. - AB

 

↑+1

Did you check the fluid level & condition? If it works fine when cold, I don't think the gearbox is toast.

I would forget the "guy" and try someone else.


JPN

 

a bad solenoid in the valve body will do it-it works fine when cold, but will shut down when hot. Valve body is the unit that shifts the transmission. Solenoids can be changed without taking tranny out.

2. using diagnostic box under the hood, pull ALL the codes and look them up or post here. Use Volvospeed.com for info how to pull the codes.

P.S.
2K is probably to much to spend on 1993.

 

Aisin-Warner (AW, Toyota's main supplier of automatic transmission) AW50-42 Solenoid-Related Codes (I cannot remember the dash number for 850's gearbox, but usually they keep same codes for same model, check your owner's manual or look at the label on the gearbox):

112: S1 Solenoid Circuit Positive-Side Short Circuit
121: S1 Solenoid Circuit Ground-Side Short Circuit or Faulty TCM (Transmission Control Module)
122: S1 Solenoid Circuit Severed Wiring
123: STH Solenoid Circuit Positive-Side Short Circuit
131: STH Solenoid Circuit Ground-Side Short Circuit or Faulty TCM
212: S2 Solenoid Circuit Positive-Side Short Circuit
221: S2 Solenoid Circuit Ground-Side Short Circuit or Faulty TCM
222: S2 Solenoid Circuit Severed Wiring
331: SL Solenoid Circuit Positive-Side Short Circuit
332: SL Solenoid Circuit Severed Wiring or Faulty TCM
333: SL Solenoid Circuit Ground-Side Short Circuit or Faulty TCM

If the solenoid is shot, one or more of these codes should generally appear on an OBD-II scanner, or at OBD-I terminal. I said generally, because Volvo's self diagnostic is sometimes not very accurate or overly sensitive.

I've never worked on the solenoid before, but if the wiring can be visually inspected, see if you can disconnect, clean and re-connect the connector to see if it solves the problem, or if there is a wire that is damaged. If not, you may need a new solenoid assembly.

>P.S.
2K is probably too much to spend on 1993.

Agreed.

Good luck,


JPN

 

Did you sort this out? Mine is changing from 1st to 4th after warmup. TSS shows a fault, this was replaced and still the same problem exists. All works fine when cold.

 

If it shifts when it's cold. That means your tranny is NOT toast! Go tell that so-called mechanic to wipe his greedy rag on some one else! I swear$$$ bastards!