I can use all the help I can get on this one. Beating my head against the wall at this point.
2005 GMC 2500 6.6 Diesel
### 1/18/2020 @ 8am (16 degrees snow & ice)
* Truck has sat since 1/10/2020. Drove around 40 miles in the snow on the that day.
* Started truck, transmission selector (underscore under gear) not present. Put in drive started up the driveway. Lost power half way up. Reverse not present, only 1 gear.
* Upon restart truck showed “Range Shift Inhibited”
* Check engine light was on and code read “P0700” Malfunction with Transaxle Controls.
### 1/20/2020 @ 4pm (36 degrees, sunny)
* Truck didn’t move from driveway over night due to no available reverse gear.
* Checked all connections to the TCM to determine if a pin had slipped out. Looked fine.
* Purchased Ignition Switch and NSBU Controller.
* Changed out Ignition Switch
* Truck started, Check engine light went off.
* All gears were available and no warning lights.
* Took truck for test drive. Out of driveway, 300 yards, shifted to second, maybe third gear. Truck lost power ABS & Brake light came on and displayed “Service Brake System” on dash.
* Limped the truck into a place to turn around, put truck in 1st gear and slowly drove back to house.
* Truck did not show a check engine light so no code was present.
### 1/21/2020 @ 3pm (33 degrees, rainy)
* Started truck to check if anything had changed. Exhibited same scenario.
* Note: parking brake had been pretty bad. Every once in a while I had to engage and release the brake because it had fallen in to the engaged position but the brake were so bad it didn’t actually engage. This made the “Brake” light go right off.
### 1/22/2020 @ 5pm (Truck was in heated garage all day, 72 degrees)
* Purchased and installed rear brake pads
* Drivers side rear was down to metal.
* Passenger side rear needed to be changed but not terrible.
* Both front brakes looked almost perfect.
* All rotors looked and felt fine. No vibrations or groves ever.
* Started truck, “Service Brake System” still read out on display.
* Check engine light illuminated with code: P0802 - Transmission Control System MIL Request Circuit/Open.
* Cleared Code. Restarted. Check engine light came back on. Same code.
* Drove about 300 ft to park it and I am observing hard shifting when going from park to reverse to drive. This has not been observed before.
### 1/23/2020 @ 4:00 (Truck in heated garage)
* When first started just the “Service Brake System” was showing, No gear indicator but no “Range Shift Inhibited” or check engine light.
* Cleaned ABS sensors on driver front. Didn’t show signs of any issues.
* Cleaned and lubed parking brake on passenger rear. Notice it wasn’t returning to an open state. I could motivate it by tapping it back in place with hammer/screwdriver. Left in fully open state, did not clear “Service Brake System”
* When restarting the truck, “Range Shift Inhibited” returned as well as the Check Engine light. Code was P0700- Malfunction with Transaxle Controls.
* Reverse was not available. Drive was underpowered as well as 1st.
* Replaced NSBU controller.
* No change. Cannot remove truck from garage due to no Reverse.
2005 GMC 2500 6.6 Diesel
### 1/18/2020 @ 8am (16 degrees snow & ice)
* Truck has sat since 1/10/2020. Drove around 40 miles in the snow on the that day.
* Started truck, transmission selector (underscore under gear) not present. Put in drive started up the driveway. Lost power half way up. Reverse not present, only 1 gear.
* Upon restart truck showed “Range Shift Inhibited”
* Check engine light was on and code read “P0700” Malfunction with Transaxle Controls.
### 1/20/2020 @ 4pm (36 degrees, sunny)
* Truck didn’t move from driveway over night due to no available reverse gear.
* Checked all connections to the TCM to determine if a pin had slipped out. Looked fine.
* Purchased Ignition Switch and NSBU Controller.
* Changed out Ignition Switch
* Truck started, Check engine light went off.
* All gears were available and no warning lights.
* Took truck for test drive. Out of driveway, 300 yards, shifted to second, maybe third gear. Truck lost power ABS & Brake light came on and displayed “Service Brake System” on dash.
* Limped the truck into a place to turn around, put truck in 1st gear and slowly drove back to house.
* Truck did not show a check engine light so no code was present.
### 1/21/2020 @ 3pm (33 degrees, rainy)
* Started truck to check if anything had changed. Exhibited same scenario.
* Note: parking brake had been pretty bad. Every once in a while I had to engage and release the brake because it had fallen in to the engaged position but the brake were so bad it didn’t actually engage. This made the “Brake” light go right off.
### 1/22/2020 @ 5pm (Truck was in heated garage all day, 72 degrees)
* Purchased and installed rear brake pads
* Drivers side rear was down to metal.
* Passenger side rear needed to be changed but not terrible.
* Both front brakes looked almost perfect.
* All rotors looked and felt fine. No vibrations or groves ever.
* Started truck, “Service Brake System” still read out on display.
* Check engine light illuminated with code: P0802 - Transmission Control System MIL Request Circuit/Open.
* Cleared Code. Restarted. Check engine light came back on. Same code.
* Drove about 300 ft to park it and I am observing hard shifting when going from park to reverse to drive. This has not been observed before.
### 1/23/2020 @ 4:00 (Truck in heated garage)
* When first started just the “Service Brake System” was showing, No gear indicator but no “Range Shift Inhibited” or check engine light.
* Cleaned ABS sensors on driver front. Didn’t show signs of any issues.
* Cleaned and lubed parking brake on passenger rear. Notice it wasn’t returning to an open state. I could motivate it by tapping it back in place with hammer/screwdriver. Left in fully open state, did not clear “Service Brake System”
* When restarting the truck, “Range Shift Inhibited” returned as well as the Check Engine light. Code was P0700- Malfunction with Transaxle Controls.
* Reverse was not available. Drive was underpowered as well as 1st.
* Replaced NSBU controller.
* No change. Cannot remove truck from garage due to no Reverse.