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2008 Sorento EX Transmission not downshifting under throttle.

1516 Views 24 Replies 6 Participants Last post by  Yogi-4
Edit - I'm in the US so it's the V6 gasoline engine.

I recently bought a Sorrento with 176K miles on it. It's part time 4x4 and it won't down shift when I mash the pedal or go up a hill. The trans shifts normally in auto mode only from a stop. It is maybe a bit to quickly to get in to 4th or 5th but it does it on it's own. However once in 4th or 5th it won't downshift. I can floor it and it does nothing. The ESC off light is lit.

I can manually shift the truck without any problem I can tell. Both up and down work just fine.

There had been a CEL for a lean condition (P0171 - P2187) that I believe I sorted out buy checking the intake for leaks and cleaning the crap out of the throttle plate.

Also there is no 4x4 right now. When I switch to 4 hi (trans in neutral) nothing happens. When I switch to 4lo the 4 low light blinks and still no 4 wheel drive.

I've reset the whole truck by disconnecting the battery for a few hours and I also reset the trans a few hours later by removing the fuse.

I tried to check the TPS but it's not like one I've ever seen. It has 8 pins I think and looks like it also has the throttle actuator on the same connector. What's up with the coolant line to the throttle body anyhow? There isn't any trans codes or my cheap scanner can't read them I shows "No codes found" when I select the A/T section.

Any thoughts or suggestions are welcome.
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I was just refreshing my memory from the documentation. I am not convinced you need to pull the T/C to change the sensor. The tone wheel is on the shaft, the sensor that reads it is (I'm convinced) is on the casing. The tone wheel is right next to the speedo gear on the shaft.
For sure I'm going to look on the outside before turning a wrench.

What's tripping me up is I found the description in the service manual for the "output speed sensor" and the picture above it show the sensor inside some sort of case. I can't copy paste but it says "they output speed sensor is installed in front of the parking gear to determine the parking gear rpms by counting the frequency of the pulses.

It's odd that it's not throwing a code though. I'd have though zero signal from that sensor would set a code. Things just aren't adding up to me.

Any idea of a not super expensive code reader than can pull trans and abs and CANbus codes?
they output speed sensor is installed in front of the parking gear
I have a feeling we are talking about 2 different sensors. (Which sort of makes sense o_O ) This might be the output speed sensor on the auto transmission - not on the transfer case! Some of the codes then might make more sense and the reluctance of the shop to get into the actual transmission. (Which was never intended by Kia - Transmission faults were always "replace and return faulty unit to factory for investigation".) The parking gear is part of the transmission.
I think that is it. Not on the transfer case but in the trans. Other than being a pain to get at it doesn't look bad. Remover the trans pan, removed the controller and solenoids and such, disconnect the sensor and assuming you are into the tail housing replace the sensor. Connect it and put the guts back in.

I am tempted to look in to known good used trans though but I think I'll beat my head on swapping some parts first. I really think there are two or more things happening here. The sensor not working and the trans not being in limp home mode is jamming me up though. I shouldn't be able to manually shift if it were really in limp home.
I'll keep updating though. Maybe my struggle will help someone else. Thank you for the suggestions and keep them coming if you don't mind.
Yes please do!! If my headache story can help someone else, to me, it's worth it.
On another note, it failed the state inspection for a bad upper ball joint. You have to replace the whole control arm as the ball joint is built into it. It's not that bad at all to change, actually. 3 bolts. Heading back to get it reinspected and an alignment done here shortly. I did clean up the headlight assembly while I was waiting for the control arm to arrive. I used Sylvania's headlight restorer. Holy cow they now look brand new!! $20 very well spent. What's next you ask?? Well.... the right side valve cover gasket. I already did the left side.
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