DTC Advanced Diagnostics: U3501 (1.5L Engine, PGM-FI System) (2025)
DTC U3501 : Input Power A Circuit Low Voltage
General Description
The powertrain control module (PCM) draws power for main CPU from +B_BACKUP_FI-ECU terminal, and draws power for driver ICs which drives each device from FI_MAIN_RLY_OUT terminal. If FI_MAIN_RLY_OUT voltage is a specified voltage, the PCM detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Continuous |
| Sequence | None |
| Duration | 5.0 seconds or more |
| DTC Type | One drive cycle, MIL on |
Enable Conditions
| Condition | |
|---|---|
| Vehicle | ON mode |
Malfunction Threshold
The FI_MAIN_RLY_OUT voltage is 0.07 V or less for at least 5.0 seconds.
Possible Cause
The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
- PCM internal circuit failure
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected, the MIL comes on and a Pending DTC, a Confirmed DTC, the freeze data, and the on-board snapshot are stored in the PCM memory.
Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, the freeze data, and the on-board snapshot can be cleared with the scan tool clear command.