1997 S90 - Slipping Transmission/DTC's

S90_Texas · Post by **S90_Texas** » 18 Jun 2014, 14:14

Hi everyone! I have a giant mess on my hands and need some advice and/or feedback on how to proceed. I bought a '97 S90 at an auction last December. The body and interior were in very good shape and it has barely 135,000 miles on the clock. It has a new-looking Bosch alternator and a few other parts that seemed to indicate it had been well-cared for up until recently. However, I knew the transmission would be a problem as the fluid looked like Hershey's syrup and, sure enough, when I tried to drive it, I found the transmission was slipping badly.

I pulled the engine and transmission as a unit (which seemed to be the consensus amongst the various manuals I have) only to find that there was a small, seeping leak from behind #6 between the head and crankcase, so that got fixed while it was out as well as a few other items that were a lot easier with the engine out (heater hoses, EGR hoses, etc.) Now that everything was back in the car, the car starts and runs great, though there are a few things that still need to be fixed. However, the big nightmare is now that the transmission is seriously malfunctioning.

Reverse seems to work OK, though Drive and Reverse clunk rather audibly when engaged. The forward gears however now seem to be lumped into one pile of Jell-O. There are no noticeable shifts (I carefully got the car up to about 40mph driving down the block and back) and the car slowly lurches forward from a full stop. The Check Engine light is on, and the Upshift arrow and drive mode (ESW) lights flash in an alternating pattern. My scanner pulls the following codes:

P0500 - Speed sensor A
P0740 - Torque Converter Clutch Solenoid
P0755 - Shift Solenoid B

also:
P0116 - Coolant temp sensor
P0340 - Cam position sensor circuit malfunction

I'm not terribly worried about the last two yet, at least not until I can determine how/if to fix the transmission. The transmission was a gamble, and a losing one at that, purchased off of Craigslist. The cables looked in very good condition and the fluid was clear and smelled OK.

Needless to say, I'm rather emotionally and financially invested in this car and am hoping to get some clarity on how to proceed and whether this. If it really is the solenoids, I understand they're not really that hard to replace, but I don't want to throw more money at it without knowing that's really the solution. I'm also not interested in $150 worth of towing to find out the transmission again needs to be totally replaced (or the torque converter). If that's the case, I may just walk away.

Is it possible that a mis-matched wiring harness could cause the transmission to slip so badly? Could the slipping be electrical at all? Or due to the solenoids? Thank you in advance for the advice and input!

Ethan Rode · Post by **Ethan Rode** » 18 Jun 2014, 15:12

Here's a good thread about P0500 in a 960:
https://www.matthewsvolvosite.com/forums ... =2&t=27071

Both P0740 and P0755 relate to solenoids that are easily accessible by dropping the transmission pan, as you mentioned. It'd be a good idea to check the plastic wiring connectors. They have a habit of breaking and letting the wires back out.

Good luck, Hope you figure it out!

S90_Texas · Post by **S90_Texas** » 18 Jun 2014, 16:26

Thank you for the reply. I think I'm going to start with the wiring first, making sure that each terminal is getting the proper voltage.

So you do think that either of these two solenoids could make the torque converter slip like that? Now that I'm thinking about it, it's almost behaving more like it's starting out in third or fourth gear.