DTC Advanced Diagnostics: P068B
DTC P068B:Powertrain Control Module (PCM) Power Source Circuit Unexpected Voltage

General Description

The powertrain control module (PCM) monitors the PGM-FI main relay 1 circuit for electrical malfunctions. The driver IC of the PGM-FI main relay 1 circuit is monitored for a specified number of test pulses. If a stuck or a short to ground in the PGM-FI main relay 1 circuit is detected, the PCM stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Continuous*, once per driving cycle**
Sequence
None
Duration
0.5 second or more*, 75 milliseconds or more**
DTC Type
Two drive cycles, MIL off
*: Short to ground
**: Stuck

Enable Conditions
Condition
 
Vehicle
OFF (LOCK) mode

Malfunction Threshold
Short to ground
A short to ground in the PGM-FI main relay 1 circuit is detected for at least 3 test pulses.
Stuck
A stuck in the PGM-FI main relay 1 circuit is detected for at least 75 milliseconds after the PCM commanded OFF.

Possible Cause
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
PGM-FI main relay 1 circuit stuck on failure
PGM-FI main relay 1 circuit FI MAIN RLY CL- line short to ground
Fuse blown
PCM internal circuit failure

Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, a Confirmed DTC and the freeze data are stored. The MIL does not come on.

Conditions for clearing the DTC
The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command.