My Lexus IS300 P0980 Shift Solenoid Drama.C Control Circuit High Open Short Valve Transmission Error

2005 Lexus IS300 with a P0980 Shift Solenoid C Control Circuit High Open Short Valve error code. This is me Fixing it. @Squishey

DONT CLICK THIS: https://tinyurl.com/33r6z6cu

I’ve been getting this error code for some time now. It’s P0980 Shift Solenoid Circuit C Control Circuit High
The manual says Open or short in shift solenoid valve No.3 circuit. Combing the internet left me even more confused. I couldn’t get a good idea which solenoid I had to order.

I changed the transmission fluid and it improved to only throw the code when the car wasn’t warmed up. There are some that say bending the connector does the trick. I figure for all the work that had to go in it because of an exhaust bracket, I’ll just replace it

I remembered I have a FSM Field Service Manual. There is even a Technical Service Bulletin, it is a common problem that I felt would be a lot of work, but not overly difficult. I ordered these parts, They are down in the description. Leave a comment if you find they changed.

Transmission Fluid, Toyota Type T-IV Toyota Part Number 00279-000T4-01
Transmission Drain Crush Washer Part Number: 35178-30010 cost $1.80 ea
35230-30010 Automatic Transmission Control Solenoid
Solenoid Assembly, Transmission 3Way, No.2 [aka Solenoid "C"] Part #: 35230-30010
Genuine Seal Packing (FIPG) 103 Liquid Oil Pan gasket 0029500103
It replaces 08826-00090
Transmission seal cutter SST 09032–00100

This Exhaust bolt bracket (Pipe Support bracket) that blocks these transmission bolts here.
I can’t get a socket or wrench in there because there is no clearance and the bolt sticks out so the small socket doesn’t get down on it all the way.

I picked up these go thru wrenches at harbor freight and they worked perfectly.

I kept getting the error code P0420 Catalyst System Efficiency Below Threshold Bank 1. Which is an exhaust leak. I thought I messed up the donut exhaust gasket here or messed up an oxygen sensor. Finally after tightening the bolt down really well, I was able to get that code to stop tripping.


Shift Solenoid 56 in Lbs torque or 5.66 ft lbs
Transmission Pan Bolts 56 in Lbs torque or 5.41 ft lbs
Exhaust Bolt 33 ft lbs
EXHAUST BRACKET 32 FT LBS

To test it, I drove the car around the block and then jacked it up and ran a paper towel around the new seal to check for leaks. No Leaks! So then I drove it a mile and did it again, no leaks! Finally I drove it 5 miles and jacked it up and ran a paper towel around the new seal. No Leaks and I consider it a success. Also, no more Cat code 420.

I just found this video where the gut checks the solenoids through the transmission ECU wiring box.    • "I CAN'T BACK UP!" Lexus No Reverse (...  

Chapters
00:00 - Intro Drain Pan
01:08 - Bracket Blocking Bolts
02:49 - Remove Transmission Pan Bolts
03:34 - Remove Transmission Pan
04:40 - Solenoid Replacement
08:54 - Transmission Pan Gaskets
10:34 - Transmission Pan Installation
12:35 - Transmission Fluid




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