Please help - Volvo iShift, no throttle response

For about 2 months now I cannot figure out this issue. Took it to 3 shops they cannot figure the issue out as well. Transmission was rebuilt 2 years ago and has been amazing. No issues with engine or turbo.

Basically what happens i will be driving on the highway or come to a stop and out nowhere, I will lose throttle pedal response, no cruise control, no engine brakes, you can still hear the engine running but won’t be responding. Sometimes you hit the throttle pedal and the engine will rev and will stop reving, or it will rev up a couple hundreds RPMs or couple thousands or no response at all. I have to shut the truck off for 15-30 mins then it will be good to drive again.

This issue is very random, I can be driving for 3-4 hours no problems at all, then all of sudden I lose throttle response. Sometimes it happens after 40 mins of driving in the morning or after 2 hours of driving.

This issue started after my mechanic replaced my steering wheel tilt cable and after I put in some airline antifreeze in the red air line going to the trailer. Over the 2 months I used about 3 small bottles of airline antifreeze. A few days ago I constantly drain my tanks every time I stop , about 2-4 times a day and I notice lots of water/yellow moisture coming out. Issue is still present.

Some of the codes are

Transmission ÉCU - MID 130, PSID 204, FMI 8
Transmission ÉCU, value too high, value too low, data erratic.
Brake ÉCU - MID 136, SID 4, FMI 2

Sometimes this code would come on

Engine ÉCU - MID 128, SID 230, FMI 5

ABS & TCS Light only come on when it’s raining right snowing then goes away... these lights would come before this issue started.

Also only when E log is connected to the port I get these 2 codes, when E log is disconnected these codes go away,

Brake ÉCU - MID 136, SID 103, FMI 9
Brake ÉCU - MID 136, SID 89, FMI 9

these 2 codes show active for steering angle position sensor and yaw rate sensor but we checked these and their both fine.

 

Some people saw it’s the ribbon harness in the transmission? Can I replace this harness without removing the transmission?

 

Thanks for the reply. The truck drives perfectly fine once I start the day and only after a 2-3 hours of driving it will start to cut off for 10 seconds and go then repeat every 20-40 mins, once I shut off the truck for 30 mins it’s as if the problem never existed. Could it be a air issue somewhere ? Could a bad pressure control valve on the transmission tank cause this issue? The ishift is shifting perfect showing no issues and it was rebuilt 2 years ago and it had a new clutch actuator put in. I can fly through hills with this truck up, down, left, right with 80k lbs but this issue is very random. I noticed it only happens right below the 100PSI mark. I’m not noticing any large air leaks, I do hear a small air leak though somewhere

 

Ok will check and let you know thank you

 

But this happens while on cruise control as well? Would the sensor still be involved ?