U302D code meaning
Ignition Output On/Start
What U302D means
U302D concerns the output that powers the On/Start circuits, i.e. everything that has to work with the engine running and through cranking but not in Off or Accessory. On GM's 2012 pickups the body control module handles this by switching the coil of the run/crank relay over circuit 5199. GM bulletin PIT5817A, covering 2020–2021 models such as Escalade, Tahoe, Corvette and CT5, shows what goes wrong on that side: the BCM keeps driving ignition main relay KR73 after shut-off, circuit 5199 stays live and the battery runs down, while engine, transmission and brake controllers store P2535 and the cluster stores U300D; the repair is a new BCM. GM records that case through input codes in the receivers, not as U302D. A module that checks its own on/start output would catch the same fault at the source. No manufacturer documents U302D publicly.
U302D at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U302D
- Battery repeatedly flat, often after a remote start
- Engine lamp at start-up with P2535 stored in engine and transmission modules
- No start or modules without power if the output fails open
Common causes of U302D
- Most likelyRelay driver in the body control module staying on after shut-off
- PossibleIgnition main relay contact welded or relay not pulling in
- PossibleRelay coil control wire open or shorted to voltage
- Less likelyRetrofitted device feeding voltage back into the run/crank circuit
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Ignition outputIgnition relayBody control moduleOutput wiring
What each part of U302D means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 2D | The exact fault in that area. |
What to do next
- Note U302D 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 U302D
What does U302D mean?
U302D means "Ignition Output On/Start". U302D concerns the output that powers the On/Start circuits, i.e. It is a generic code, so it means the same on every make.
Is it safe to drive with U302D?
U302D does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U302D fail an emissions test?
U302D 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 U302D to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U302D clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.