5AT gear selection problem

Thanks in advance for any leads; admittedly I’ve done no diagnostic work but I’ve found it’s often easier these days to start with a keyboard than a wrench...

I have the 5 speed auto on my TRD OR, 120k miles. Recently I cannot manually select “2” or “L”. The shift level will move into position, but the lights do not illuminate on the dash, and the truck does not downshift into those gears. If I leave the lever in one of those 2 positions, it will behave as if it is in “D”, and move through all 5 gears plus overdrive. This is quite an inconvenience for engine braking on long descents. Thoughts? The trans is super quiet, all shifts are smooth. I know the fluid level is proper (I had the joy of bursting a trans cooler line ~7k miles ago and personally did the repair). I would be psyched to find out it’s the switch or contacts or something simple. I searched for similar issues and haven’t found any, but am hoping someone else has been through this already.
Thanks again

 

I’d you can not get it into 2 and the light does not illuminate, I’d suspect a bad Park Neutral Safety Switch. There is a possibility the shift linkage is out of alignment, but I’d doubt it.

Look here for a similar issue. It’s not exactly your issue, but it might help you.


https://www.tacomaworld.com/threads/2005-auto-5sp-wont-stay-in-low-1st-gear.677616/#post-23847298

 

My guess is electrical gremlins. Which can be simple, or hard to track down. I've seen situations where mice have gotten under the hood and chewed insulation off wires leading to weird transmission issues. The fix was as simple as shrink wrapping the exposed wire.

 

Follow the shift cable to the transmission. On the other side is a switch. This switch will bind up over time causing the shifter to be hard to move.
Spray that switch on both sides with WD-40 or something and run the shifter back and forth. It may need several sprayings to make it feel normal again.

 

Thanks for the replies. There is no stickiness anywhere in the shift gate, nor does the lever refuse to move into any position. It moves smoothly through each position, but if I leave the lever in “2” or “L” the truck behaves as if it’s in “D”. It will remain in “3” or “4” if I select those. Starting to sound like an electrical issue. Does the signal for these positions come from the Park Neutral Safety switch?

 

I believe that switch tells the computer(s) which hear you've selected. Then sends a signal to the appropriate light on the dash.

From what I've read here, 1st and 2nd gears are actually gears. The rest controlled through solenoids in the tranny.

I'd be looking at the switch on the tranny first.

Perhaps someone has the details on the switch and you could verify its operation with a multi meter.