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Home >> Jeep >> 2021 >> Renegade Trailhawk >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> 1.3L - DTCS P0108 To P025C >> DTC Troubleshooting >> P025A: Fuel Pump Module Control Circuit Open >> Possible Causes
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Possible Causes

FPCM 1 DTC FPCM 2 DTC INTENDED FAILURE MODES POSSIBLE CAUSES PCM/FPCM REACTION
P025A P027A Missing or invalid PWM Command signal from PCM
  1. PCM to FPCM Command Signal open
  2. PCM to FPCM Command Signal shorted low or high
  3. Invalid PWM signal - frequency out of range
  4. FPCM
  5. PCM
  • FPCM defaults the output to 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
  1. FPCM Output partially shorted to ground
  2. Faulty Fuel Pump
  3. 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)
  1. High resistance in the Fuel Pump Relay output circuit
  2. FPCM
  • PCM requests 100% Fuel Pump operation
  • FPCM defaults the output to 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)
  1. Charging system issue
  • PCM applies over voltage strategy
  • FPCM reacts to PCM input command
P064A P026E Current draw exceeds calibrated threshold
  1. Fuel Pump PWM Control circuit shorted to voltage
  2. Faulty Fuel Pump - internal short or high mechanical resistance
  • PCM reduces PWM duty cycle until issue clears
  • FPCM reacts to PCM input command
P0628 P2633 FPCM output to Fuel Pump shorted to ground
  1. Fuel Pump PWM Control circuit shorted to voltage
  • PCM reduces PWM duty cycle until issue clears
  • FPCM reacts to PCM input command
P0629 P2634 FPCM output to Fuel Pump shorted to voltage
  1. Fuel Pump PWM Control circuit shorted to ground
  • FPCM output to Fuel Pump to 50% duty cycle for a calibrated period. If condition continues, shut down output driver.
P1206 P120B FPCM output to Fuel Pump open circuit
  1. Fuel Pump PWM Control circuit open
  2. Fuel Pump Return/Ground circuit open
  3. FPCM Ground circuit open
  4. FPCM
  • PCM reduces PWM duty cycle until issue clears
  • FPCM reacts to PCM input command
P1205 P120A FPCM Micro internal fault
  1. Fuel Pump Control Module
  • FPCM continues to run in normal mode - run Fuel Pump according to PCM command signal
P062A P062A 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
  1. Fuel supply tube broken/leaking
  2. Fuel supply tube pinched/restricted
  3. No fuel in the Fuel Tank
  4. FPCM defaulted to 80% due to another failure detected
  5. FPCM duty cycle output reduced due to another failure detected
  6. Faulty Fuel Pump
  • PCM requests 100% Fuel Pump operation
  • FPCM defaults the output to Fuel Pump to 80% duty cycle
U0109 U016C PCM Loss of Communication with FPCM
  1. FPCM PWM Feedback circuit open
  2. FPCM PWM Feedback shorted low or high
  3. Fuel Pump Relay output circuit to FPCM open or shorted to ground
  4. FPCM Ground circuit open
  5. Fuel Pump PWM Control circuit shorted to ground
  6. FPCM
  7. PCM
  • PCM requests 100% Fuel Pump operation
  • FPCM defaults the output to Fuel Pump to 80% duty cycle

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

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