Finally got it out. Now I have yet another question:
How do I determine if this solenoid is bad? Is there a way to check it with a voltmeter for resistance or something? I originally got a "shift solenoid A" DTC code. Should I trust that this solenoid is bad, or can I check it to make sure? n It's like the car only has third gear or something, and won't downshift into 1st or second....it stays in high gear all the time, I get the trans. up arrow flashing and the CEL is on. Any thoughts? It's in "limp" mode for sure. I just don't have the money to just throw parts at it, and I want to make sure I replace the right solenoid...Thanks guys

 

bumped...

 

I'll bump you all right

You should be able to test it for continuity. It's just an electro-magnet so it should have a complete circuit through it. If the circuit is open it's definitely bad. If your meter on "ohms" reads infinite, same thing - bad.

This article had testing and values in it.
http://www.matthewsvolvosite.com/for...hp?f=1&t=47779

 

Dude, you are the man!! I tested the S1 and got a resistance value of 14.2 ohms. I think that may be borderline ok, so I'm gonna check the S2 tomorrow. Thanks so much for the help. If I run into you sometime, I'll have to buy you a beer!

 

Thank you for saying so. I've found most people on here are truly helpful and it's a matter of each of us saving the other from a painful visit to the dealer.

 

Okay, I got the S2 out and it reads 14.6 ohms......

Okay, so they both seem like they are in spec, so now what?? Is there another shift solenoid I am missing? All the wiring I have seen and come in contact with has looked good so far and all the connectors and clips are all there and in great condition, so I am frustrated. Please forgive my rant. I am almost bald, but I'm pretty sure I will be totally hairless when this job is over!

 

Cking a solenoid with a VOM is only one test and it is inconclusive; i.e. if it fails the resistance test then it's definitely bad, but passing the resistance test doesn't mean it's necessarily good either.

Google "automatic transmission solenoids + testing"

Here are some hits:



// this one is educational and nice robot voice too:



BTW: What was your specific fault code? Did the trans have shifting problems?

 

The coil inside could be good. When the computer energizes it, it does produce a magnetic field but the rod inside might be jammed, stuck, corroded .... whatever and it's not moving. The computer thinks everything is ok as electrically it's reading normal but physically it isn't opening or closing the fluids path as it should.

 

gdog, the computer is throwing a"shift solenoid A malfunction" code and the trans. up arrow is on, along with the CEL. Also the car is in limp mode is only using high gear. It will not shift into 1st, or low gear.

 

Okay, another update in this saga;

Thanks gdog for the two videos posted earlier. I watched both videos and then hooked up an air line to each solenoid one at a time and then supplied 12v to the electrical connector. Both the S1 and the S2 operated properly and they both opened and closed as they should with no air leaks at 40psi air pressure. I was afraid to use any more air press. because I didn't want to blow out the guts in the solenoids. I believe they are not the culprit.

So now, I have to think that the supply wires that feed these solenoids has an issue, either by not supplying the power to the solenoid leads, or maybe when I put the trans. in drive, or low, the wires are not hot when they should be to operate the solenoids...

Please keep the ideas and suggestions coming, as I have ran out of ideas. I wonder if maybe a fuse for the transmission has blown somewhere...or if there is a malfunction in the gear position switch on top of the tranny...would that switch turn on/off the power to the solenoid feed wires?

 

If the PNP switch on top of the transmission is going it should change the way the solenoids work as that would be part of selecting D, 3, 2 or 1. If the switch is telling the computer you want second gear and you actually have it in drive it's going to act up.

I think I missed the PNP from your first post because I was answering your question about the solenoids.

Have you tried to "row" it slowly through all gears a number of times yet?

 

So the switch on top of the trans is the pnp switch. Ok. Is there a way to check that the pnp is activating the solenoids in the car's current state? What I mean is, can I connect the trans. harness and battery and row it through the gears, and check that the solenoids are in fact operating? Or can I use a test light on the solenoid feed wires to check that they are getting power when I shift through D-2-1?

 

anyone?

 

I am almost sure it is the pnp switch. If I understand this correctly, the contacts in that switch control the power to the solenoids when you shift into D,2,1. Also, it makes sense that the computer would spit out the code "shift solenoid A malfunction" because the solenoid would not be getting any power to operate. It would also explain why I have no blown fuses anywhere, and why I have no 1st or 2nd gear. I'll let you know on Wednesday if this is the fix...

 

Dude, I gotta say it, you're impressive! Most DIYers would not even attempt what you have done so far; hat's off to you.

Now onward. Don't know about your leaning toward the PNP switch. The PNP supplies signals to the TCM (trans control module); it's the TCM that interprets those inputs from the PNP and then sends high-side (12v) signals to the shift solenoids to activate them. You could ohm out the wires from the solenoid connectors back to the TCM pins just to be sure there's not a problem there. Do you have a schematic?

And 40 psi is nothing to these solenoids; they can see upwards of 200 psi. So crank it up and try again.

Back to your DTC or Pxxxx code; what was the actual code number please?

I found a doc in my collection you should read: AutoTransDiagnosis.pdf. It's a volvo doc with lots of good info. Will see if i can find it on the web for you...
Here it is:
http://www.volvoclub.org.uk/tech/ser...sDiagnosis.pdf

 

gdog, thanks for hanging in there to help me get this figured out. I am a mechanic as well, but unfortunately, not a Volvo mechanic. My hat's off to you for reading this. This thread is getting long winded, but I need to get this car past emissions for a friend of mine. So now, ONWARDS we go!!

To answer your questions,

No, I don't have a schematic, and the obd code I got was a P0750 shift solenoid A malfunction.

Also, I will retest the solenoids tomorrow afternoon before work, and I;ll jack up the pressure to make sure the solenoids are okay.

I am reading the link you gave, and will ohm out the feed wires tomorrow as well.

 

Here's where i got most of my docs:
Volvo 850 Maintenance And Service Documents

Look at SystemWiringDiagrams.pdf there for schematics. TCM connections are in there. Unfortunately these docs are all for '95 MY but don't think they changed much between years.

That P0750 code points to S1 not functioning, so if the electrical connections ck out, I would replace the solenoid.

Usual Disclaimer: Keep in mind this is all my opinion based on the info i have access to; ultimately you need to make the call..