P2780 code meaning
Downshift Switch Circuit Low
What P2780 means
P2780 tells you the downshift switch voltage has fallen under its lower limit. GM's twin-clutch TCM (tables 23OBDG07 and 24OBDG07) checks the TAPDN input against 2.519 V; if the signal stays under that mark for 150 ms while the supply is inside 8.75–18 V and the starter is not engaged, P2780 is logged as Type C, no MIL. In Ford's TR9070 listing from July 2024, P2780 is the out-of-window-low entry for the downshift paddle. A minus-paddle signal pulled toward ground usually comes from a wire rubbed through near the steering column, a pinched harness behind the wheel trim or an internal short in the switch. P2781 is the high-side failure, P2779 the implausible value within range. Manual downshifts are lost; automatic operation carries on.
P2780 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2780
- Downshift paddle has no effect
- Manual mode not available, normally no check engine light
Common causes of P2780
- Most likelySignal wire rubbed through or pinched to ground
- PossibleMinus paddle shorted internally
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Downshift switchWiring harness
What each part of P2780 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 7 | Area: transmission. |
| 80 | The exact fault in that area. |
What to do next
- Note P2780 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2780
What does P2780 mean?
P2780 means "Downshift Switch Circuit Low". P2780 tells you the downshift switch voltage has fallen under its lower limit. It is a generic code, so it means the same on every make.
Is it safe to drive with P2780?
P2780 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P2780 fail an emissions test?
P2780 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P2780 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. This is a job for a workshop.
Will P2780 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.