Still trying to not blame the transmission for my issue. The short of it is, that my 850 transmission is shifting
1) too early, but does go through each gear. It shifts into the next highest gear before it should, causing a little bogging, but does go through each gear
2) releases too late. It doesn't release the high gear it is in until really bogging down

What controls this? I believe I MAY have a bad solenoid, as the 'L' position on the shifter should allow the car to shift between first and second gear, but it never leaves first gear when in L. In '3' it goes 1-2-3 no problem, and 'D' = 1,2,3,4 just fine.

No cel, no arrow, no codes (95, so OBD1 and 2)

Replaced PNP switch by mechanic (no change). Replaced TPS, which fixed another issue I had (cold starts).

How does the Speed Sensor play in this? Is this the same unit that measures Speedometer speed? If I recall correctly the GPS I had in the car said I was going say 50, but the speedo says 45...

Anyway, 'What does the TCM look at to determine shift points/when to up and down shift?' I would like to swap TCMs with a known good as well to see if something went in the board... it has a slight rattle (like solder broke off) when shaken.

I have a replacement transmission standing by if it is in fact the solenoids, but I'd rather not pay the $ to install it if not needed =D Fluid level is fine and clean red.

 

As you mentioned it uses the TPS signal and the wheel speed sensors signals. There is a communications channel between the TCM and the ECU so they could be sharing other information too, like RPM.

Is kickdown working ok? Does the tranny shift down correctly when you floor the throttle?

Have you cleaned the wheel sensors? Is your ABS working ok?

 

ABS - Yes, just did a brief test and I got 3 pulses (was only going about 30 in the parking lot), and it did come on, no errors/warning lights. Cleaned wheel sensors? No, haven't done that. Finally have a Haynes, so I can look there or poke around online (unless you have it handy).

Kickdown does work. If I am in the wrong gear (3rd or 4th typically) and I put the pedal down even a quarter of the way, I will get my kickdown, which seems to work fine. Not super smooth though, but would be acceptable if everything else was going on at the correct time.

Also of note, I use very little of the pedal travel, as in, I *never* use half of the travel (the 50% point) unless I am consciously trying to use the travel up... but I think this is typical of most cars, no? I also just coast along as I do not have much traffic to worry about, and only go the speed limit... =)

 

http://www.matthewsvolvosite.com/dow.../Volvo_850.zip

This one might help you too.

Have you gone to a Volvo dealer to get your TCM scanned with a Volvo Scan Tool?

 

I went in to ask them to run the tests to test S1, S2, and SL solenoids and they basically told me not worth replacing them because it will just 'bite us in the end', in the end. I can scan for transmission codes with OBD1, and originally had some, but no one has come back.

 

Also, if I am in drive, and idling (starts off from 1st just like it should), if I hit the winter mode button, the car stalls in less than 4 seconds (last 2 times I've tried it). Instead of starting off in 2nd like the button is supposed to, it's trying either 3rd, or 4th! Kills the car, dead. Does not do this in L, 3, R, or N. Not sure if Winter Mode Button even 'works' in those settings, but just something to note... SOMETHING is telling the trans to be in too high of a gear, it might a slow/lazy solenoid (makes sense), but want to make sure before swapping out.

 

!! After reading the two pages posted, I get kickdown much, MUCH easier than 'flooring' the pedal... again, less than 50% and it will kick down from the too high 3rd or 4th, into a lower gear... I've never even come close to flooring the pedal... Don't see how this could be causing my issue but I'm open to ideas... Also, it seems there is a Vehicle Speed Sensor as well as a Transmission Speed Sensor...

Does the VSS do Speedometer speed? How difficult is it to replace the TSS? Looks like it's just as bad as S1, S2, and SL... (pita involving dropping the subframe (part, anyway) ).

 

I have no idea. I hope somebody else can help you.

 

Are you able to get kick down by going <50% of throttle travel?

 

When I want kick down I usually do 100% throttle, so I can´t answer your question right now. I´ll check that the next time I use the Volvo.

 

Would be appreciated... I wonder if adjusting the kickdown cable could help... ? =\

 

My 854 kicks down at 50% throttle. Regarding the wheel speed sensors, I don't know if that info is accurate. I was thinking more about that yesterday and it doesn't make too much sense that the TCM would need signals from both wheels. I probably just asks the ECU what the current speed and RPM are, plus the TPS signal. That should be enough to calculate gears. Obviously it receives the gear selector signal too.

 

One last big help. Put the car in 'L'. Does it EVER shift to second gear. Mine does not... that's why I think (I forget which, S1 or S2, I lookd it up via PDF) is 'lazy' or slow or stuck or something... Transmission replacement set up for Monday .

 

Your car doesn't have a kick down cable the computer controls the kickdown through the TPS and the TCM and ECM.
Yes in L it should shift into second.

 

Never has, and I've had it to 5k and pretty much up to the speed it is going to get... I will read the manual and see when it is supposed to... sounds like solenoid as per mechanic...