Possible Causes

Always perform the PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

The table below shows the FPCM DTCs and the correlating INTENDED failure modes. NOTE: On some vehicles the faults may not always set as expected which may lead to a misdiagnosis (See the know issue information). Therefore, it is usually best to perform the "Complete Fuel Pump Control Module System Testing (Not DTC Specific)" in the diagnostic information.

FPCM 1 DTC	FPCM 2 DTC	FAILURE MODES	POSSIBLE CAUSES	PCM/FPCM REACTION
P023F	P2632	Missing PWM Command signal from PCM	PCM to FPCM Command Signal open PCM to FPCM Command Signal shorted low or high FPCM PCM	If the PCM is unable to communicate with the FPCM the U0109 or U016C will also set.
P025A	P027A	Invalid PWM Command signal from PCM	PCM to FPCM Command Signal shorted low or high Invalid PWM signal - frequency out of range FPCM PCM	FPCM defaults the output to the Fuel Pump to 80% duty cycle. NOTE: It is not uncommon for the P025A DTC to set erroneously for several other failure modes.
P025B	P027B	Output driver over temp	FPCM Output partially shorted to ground Faulty Fuel Pump (high mechanical resistance) Faulty FPCM internal driver	PCM sets fault, waits a calibrated period and commands a safe duty cycle. FPCM output to Fuel Pump to 50% duty cycle for a calibrated period. If over temp continues, shut down output driver.
P025C	P027C	System under voltage - Fuel Pump Relay output voltage to FPCM is below a calibrated threshold (approximately 6.0 volts)	High resistance in the Fuel Pump Relay output circuit FPCM	PCM requests 100% Fuel Pump operation. FPCM defaults the output to the Fuel Pump to 80% duty cycle.
P025D	P027D	System over voltage - Fuel Pump Relay output voltage to FPCM is above a calibrated threshold (approximately 16.0 volts)	Charging system issue	PCM applies over voltage strategy. FPCM reacts to PCM input command.
P0628	P2633	FPCM output to Fuel Pump shorted to ground	Fuel Pump PWM Control circuit shorted to ground	PCM reduces PWM duty cycle until issue clears. FPCM reacts to PCM input command.
P0629	P2634	FPCM output to Fuel Pump shorted to voltage	Fuel Pump PWM Control circuit shorted to voltage	FPCM output to Fuel Pump to 50% duty cycle for a calibrated period. If condition continues, shut down output driver.
P064A	P26EA	Current draw exceeds calibrated threshold	Fuel Pump PWM Control circuit shorted to voltage Faulty Fuel Pump - internal short or high mechanical resistance	PCM reduces PWM duty cycle until issue clears. FPCM reacts to PCM input command.
P1205	P120A	FPCM Micro internal fault	Fuel Pump Control Module	FPCM continues to run in normal mode - run Fuel Pump according to PCM command signal.
P1206	P120B	FPCM output to Fuel Pump open circuit	Fuel Pump PWM Control circuit open Fuel Pump Return/Ground circuit open FPCM Ground circuit open FPCM	PCM reduces PWM duty cycle until issue clears. FPCM reacts to PCM input command.
P2635	P2635	Actual fuel pressure is above or below the desired fuel pressure by more than a calibrated threshold. Fixed pressure system - 5.8 psi above or 14.5 psi below Variable pressure system - 10.9 psi above or below	No fuel in the Fuel Tank Fuel supply tube broken/leaking Fuel supply tube pinched/restricted FPCM defaulted to 80% due to another failure detected FPCM duty cycle output reduced due to another failure detected Faulty Fuel Pump	PCM requests 100% Fuel Pump operation. FPCM defaults the output to the Fuel Pump to 80% duty cycle.
U0109	U016C	PCM Loss of Communication with FPCM	FPCM PWM Feedback circuit open FPCM PWM Feedback shorted low or high Fuel Pump Relay output circuit to FPCM open or shorted to ground FPCM Ground circuit open Fuel Pump PWM Control circuit shorted to ground FPCM PCM	PCM requests 100% Fuel Pump operation. FPCM defaults the output to the Fuel Pump to 80% duty cycle.