1990 q45 2nd gear is not engaging.

[subtle_driver]

So my q45 was shifting perfectly, no slipping, etc. until after an oil change.I put my car on the lift for an oil change then I took it home. This is what happened immidiately after, on the drive back:

First gear nothing unusual, no slipping even on a wot pull. Then it switches to 2nd; 2nd gear acts as if the transmission was in neutral, it just revs and does nothing. Then if I let off on the throttle, it will engage 3rd. 3rd gear does not slip and engages just fine then smoothly shifts into 4th. 4th acts just as normal as 1st, and 3rd. 2nd won't engage when driving normal or when i kick it down. It does the same when i manual shift to 2nd. And the scanner shows that the gear selector is working properly. The TCU has no codes, and the ECU shows nothing, and the ABS is perfectly fine too.

Is there something i could have bumped or jostled when i changed my oil that would directly effect 2nd gear? I already swapped out the tcu with a known good one, but nothing changed. The fluid is at the correct level, and I have a external transmission cooler added, and I change my fluid and filter screen and clean off the magnets every 15k.

If i can't fix this cheap and quickly, ie. sticky solenoid, or connector, then I'm Swapping in a z32 5-speed. I'm looking for parts if you have anything that will help lmk. thanks!

I checked the I did some searching last night untill 1am, and called around today and checked the connectors and diagrams but nobody seems to have encountered this before. And I'm pretty stumped. Thanks again.

[goody90q45]

There's a connector cluster under the transmission for 3 external sensors- revolution sensor, turbine revolution sensor and (brain f*rt) I can't think of the third sensor. All three can be ohm tested to see if they're functioning properly. They talk to each other and the TCU to tell the transmission when to shift. Read through the transmission section of the FSM for the testing of each sensor. Ohm testing is a DIY and will take about 5 minutes laying on your back under the car.

In my case, my 94Q would occasionally refuse to shift from 1st to 2nd and the cure was to pull over, turn off the engine for 2 seconds and restart. It was a dead turbine revolution sensor that took a shop less than 30 minutes to replace. It sounds like you may have the same problem.

[qship96]

"I race it at rally,autocross,drag,and drift" lots of stress on the old girl

[subtle_driver]

There's a connector cluster under the transmission for 3 external sensors- revolution sensor, turbine revolution sensor and (brain f*rt) I can't think of the third sensor. All three can be ohm tested to see if they're functioning properly. They talk to each other and the TCU to tell the transmission when to shift. Read through the transmission section of the FSM for the testing of each sensor. Ohm testing is a DIY and will take about 5 minutes laying on your back under the car.

In my case, my 94Q would occasionally refuse to shift from 1st to 2nd and the cure was to pull over, turn off the engine for 2 seconds and restart. It was a dead turbine revolution sensor that took a shop less than 30 minutes to replace. It sounds like you may have the same problem.

I'll try this sometime next week. thanks for the tip! I appriciate it!