P080DUpshift/Skip Shift Solenoid Control Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- GM's skip-shift (CAGS) on manual gearboxes such as the T56 and TR6060 uses an engine-module solenoid that, at light load, blocks the way from 1st into 2nd so the driver shifts 1 to 4; the 1-4 lamp shows it (P0804). The engine module drives the solenoid with a low-side driver; P0803 is the open circuit. P080D means the control line is shorted to positive: with the low-side driver on, the line should be pulled to ground but reads high (GM: 0.5 Ω or less to the supply). The solenoid cannot be energized and the driver is protected or switched off. GM checks it only with the driver on, from 9 V (2015/16: 11–32 V) and above 250 rpm, 5 of 6 samples of 250 ms, type B with the MIL after two trips in all tables from 2015 to 2019. Without power the solenoid does not lock, so 1 to 2 stays free.
- What you may notice
- Check engine lamp after two trips
- 1-4 lockout not working
- Otherwise no change in driving
- Likely causes
- LikelyControl wire shorted to battery voltage (damaged harness)
- PossibleSolenoid coil with shorted turns (resistance near zero)
- PossibleSubstitute resistor ('eliminator') with too low a value
- RareEngine module driver faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.