2001 Oldsmobile Aurora Trans Issue

[strongt]

My 2001 Oldsmobile Aurora has the 4T80E trans has been having a weird shifting issue. It's been having shifting issues now that the temps in my area have been above 100 degrees. What's been going on is when its cold or the temps are below 100 outside it shifts just fine. Above 100 degrees, it's fine if started cold and will shift fine on the road till I shut it off. If I restart the car in a few minutes it'll shift very hard into gear. If I disconnect the battery, then start it. She will shift fine after the computer resets.
Sometimes I can just turn the car off, then back on and it will start shifting fine again.

Trans has had the filters & fluid changed, but no change in it's hard shifting above 100 degrees outside. The funny thing is it'll only happen if I just shut the car off like to fuel up and start it up and put it into R or D?

Any idea's guys ?

Also no codes stored.

 

[Chris142]

I'm guessing a solenoid is acting up when warm.

 

[14Accent]

PCS (pressure control solenoid) heat soaking when you turn it off, also possibly a sticking pressure valve in the valve body.

Try dumping a can of trans tune in it for starters, then possibly add an aux. cooler to keep trans temps down.

 

[clinebarger]

I'm thinking PC Solenoid (Pressure Control Solenoid)..... Sometimes called a "Force Motor".


*Your driving around from a cold start with the "Applied Amperage/Duty Cycle" to the PC Solenoid varying all over the place.
*The Solenoid gets nice & hot.
*You shut off the vehicle off.
*The Solenoid slams shut....No amperage applied & gets stuck in the "Max Torque Signal" position when amperage is restored on the hot start.
*It can be unstuck by cycling the the key or letting cool down.

This NOT a condition the PCM would recognize as a circuit fault.






I would like to see (Symptoms occurring & not occurring) .....

*Commanded PC Amperage/Duty Cycle via scan data.
*Actual Amperage via a meter between the 2 PC control wires.
*Actual Line Pressure via a Pressure Gauge/Transducer at the pressure tap.

 

[strongt]

Thanks guys for the info. I may have to have a shop look into it. PC solenoid is in the side cover. Got to drop the trans in this car to get the side cover off. What funny is it's maybe a 50/50 it will shift fine if I cycle the key. But its been 100% chance if I disconnect the battery it will shift fine afterward.

 

[GMBoy]

Off topic...but I had a 2001 Aurora 4.0 in deep metallic green, tan interior loaded. Loved that car! It was one of the BEST interiors GM ever did and was better than Cadillac of the time.

 

[clinebarger]

Originally Posted By: strongt
Thanks guys for the info. I may have to have a shop look into it. PC solenoid is in the side cover. Got to drop the trans in this car to get the side cover off. What funny is it's maybe a 50/50 it will shift fine if I cycle the key. But its been 100% chance if I disconnect the battery it will shift fine afterward.


I'm going off the assumption that there are NO trouble codes! That's why I would do the diagnostics that I outlined in the above post.

You "can" back the side cover off just enough to change the PC Solenoid....I can do it in 2-3 hours depending on the platform.

TIPS......
Remove the TCC Solenoid before removing the PC Solenoid (Makes access a little easier), Replace the TCC Solenoid while your in there as it will probably break anyway.

The cover O-ring will most likely stick to the main case, Carefully reinsert it back in the cover channel. Do not pull-on or stretch the O-ring!!

Be careful with the solenoid connector locking tabs, bend them just enough to release the connector.

The PC Solenoid bracket hold down bolt has a 8mm/5/16" head, A magnetic socket is a good idea here as is a extendable pencil magnet.

Use ONLY Borg Warner or AC-Delco solenoids!!!!




This is how the Upper Valve Body sits in the car (Looking at the left wheel)