Leepman65

Did the av6 swap everyone recommended. Used the FAQ on the forums.. Car will only shift into 1st and 2nd gear. Won't shift into any gear after that. What could the problem be?

fsttyms1

Did you switch over the range switch and solenoids?

Leepman65

I switched everything on the 2 transmissions just to be safe. It through a code P0780, Shift Malfunction code.

3.2TLc

Was the torque converter filled with ATF prior to installation ?
As Fsttyms1 previously suggested rechecking your work, as it may be something simply overlooked.

Check the fluid level and all of the solenoid connections after verifying that the gear range switch is ok.

P0780 = Mechanical problem in hydraulic control system

Could possibly be the shift control solenoid valve "A" or the A/T clutch pressure control solenoid valve set "A/B".

Leepman65

The transmission I got was used and it came with the original torque converter, they were both drained of fluids. I did not fill the converter prior to installing it. I filled the transmission with fluid then started the car, shifted through the gears and then added more fluid for what was pumped into the converter I'm guessing. I've help rebuild 2 Allison transmissions for durmax diesels and we always installed converters dry with no problems....

Leepman65

Is this the solenoid you are speaking of?

3.2TLc

Yeah, that's the A/T clutch pressure control solenoid valves "A/B" set.

Pull the cover with the 6 bolts on it, be careful of the plate's gasket. Underneath, you'll see 3 tubes which have screens on the bottom of each. The middle tube's screen tends to get clogged up and restrict the fluid's flow. The tubes will individually pull out, make sure that ya do only one at a time and seat them back in to the receiving hole. There's an o-ring on the bottom of each tube.

You can test the solenoids by applying power to the connector.

Leepman65

Thanks 3.2TLc. That's the only thing I didn't swap out on the transmissions. The gear range switch was fine when I had the TL trans in it, I read that when you install that on to the transmission, it has to be in neutral; I had it in park. Should that be a problem??

3.2TLc

Does the shift indicator show up normally when each gear is selected ?
If in doubt, simply readjust the gear position switch or shift cable as recommended by the manual.

Leepman65

Ok I swapped out the A/T clutch pressure control solenoid and nothing changed. I then swapped two that are ontop of the transmission under the throttle body and coolant piping. After swapping them I now have what I think is 3rd. To get it to start in 1st gear I have to shift all the way down to 1st, shift to 2nd but have to let off the gas for it to shift and then it will shift to 3rd but it is really weak like its in a higher gear or slipping really bad but can still get up to speed. What to do next? Any suggestions?

3.2TLc

Any CEL codes ?
Is the ATF fluid level ok ?
Was the gear range selector replaced ?

How many miles were on the donor "AV6" ?
Perhaps try having the tranny's line pressure checked ?

Leepman65

I haven't checked for any codes dice the last one I posted. The fluid level is good. Gear range selector was swapped from the tl trans to the av6. Miles I am unsure of. The donor vehicle had an interior fire so they couldn't confirm mileage. Where is the shift control solenoid valve "A" located?

3.2TLc

The shift control solenoid "A" is located on the front side of the tranny, just above valve "C".
It's just a bit inside towards the motor, of where the ATF sensor and 3rd & 4th pressure switches are.

ErickUa5

If I understood right:
The trans is on 3rd gear the whole time when the shifter is on D5, (meaning its in limp mode)
You're putting the shifter on 1 and 2 in order to get the car moving.

Does your speedometer currently work ?
Did you bolt down all 3 grounds on the trans ?

Leepman65

Speedometer works, I only unbolted 2 grounds. I don't think there was ever a 3rd. I looked for one could not find it. I unplug the battery to clear any codes or the limp mode. When it's in D5 it will be in a high gear when I take off. I can shift down into 1st to take off. Shift to 2nd but it lags until I let of of the gas. Shift to 3rd and it shifts really hard. Shift to 4th it shifts fine but the D5 light starts flashing, engine light comes on and I only have 2nd and 4th gear until I unplug battery and do it all over again

3.2TLc

Get the codes as they may help narrow down the problem. Could be as simple as a faulty solenoid or wiring connection ? These tranny's are electronically controlled, ya know !!!

Leepman65

P0758 shift solenoid B
Can anyone give me a location on this?

outlawspeeder

It is next to the A solenoid.

All joking aside, to orientate the image to find the shifting solenoids. This image is where they would be if the case was shown.

Hope this helps.

3.2TLc

^^^ Excellent diagram, except the way that the tranny's end case as depicted is actually in reality ,oriented upside down from the diagram shown. So, try to visualize the shown pic with the A/T Clutch Pressure Control Solenoid Valves "A & B" on top of the tranny's case. That set is located under the TB intake hose, right behind the battery. Sure hope this helps to better visualize the solenoid's positioning on the tranny !!!

Oh boy, there's sure a lot of shit to check......bah humbug !!!

3.2TLc

P0758 = Problem in Shift Control Solenoid B Circuit

Check the solenoid's wiring connection and grounds.
Check for a blown #6 fuse(15A) within the driver's side kick-panel fuse box and if ok, replace the solenoid.

Leepman65

Is there a wiring diagram out there for the transmission?

Leepman65

I tested the solenoids and they seemed fine.... Clicked everytime I put power to them

ErickUa5

If you have warranty on the trans I would ask for an exchange. The wiring diagram is in the service manual, I believe theres a thread on how to download it.