Fuel System Control Module Diagnosis
AT THE BOTTOM OF THIS PAGE, YOU WILL FIND THE YOUTUBE VIDEO FOR THIS PROCEDURE. YOU WILL ALSO FIND THE PIN OUT DIAGRAM FOR THE FUEL SYSTEM CONTROL MODULE FOUND ON 2007 AND NEWER GM VEHICLES. PLEASE REFERENCE THE DIAGRAM TO HELP PROPERLY DIAGNOSE A FAULTY FUEL SYSTEM CONTROL MODULE.
BEFORE TESTING, ENSURE THAT BOTH FUEL RELATED FUSES HAVE BEEN REPLACED:
-FUSE (56) ECM 15AMP
-FUSE (21) FSCM 20AMP
STEPS TO DIAGNOSE:
1. CONNECT PIN1 (BLACK GROUND) TO PIN16 (PINK GROUND)
2. CONNECT PIN32 (RD/WH BATT + ) TO PIN47 (GY FUEL PUMP 12+)
THIS WILL POWER THE PUMP TO RUN AND CHECK FOR A FAULTY FUEL PUMP.
3. NEXT, CHECK FOR FUEL PUMP SIGNAL AT THE FUEL SYSTEM CONTROL MODULE.
4. FIND THE DARK GREEN/WHITE WIRE IN PIN13. WITH A TEST LIGHT CONNECTED TO THAT WIRE, TURN THE KEY TO THE RUN POSITION. IF THE POWERTRAIN CONTROL MODULE IS SENDING THE SIGNAL TO COMMAND THE FUEL PUMP ON, THEN THE TEST LIGHT WILL BE ILLUMINATED.
*IMPORTANT GREEN/WHITE WIRE CONDITIONS*
CHECK FOR ONE OF THE FOLLOWING THREE CONDITIONS.
1. CONSTANT 12V POWER
2. POWER ONLY WHEN CRANKING
3. POWER FOR 3 to 6 SECONDS WITH KEY ON. WIRE/PCM INTEGRITY PASSES IF ANY OF THE THREE CONDITIONS HAVE BEEN SATISFIED.
AFTER COMPLETING THE STEPS ABOVE, IF YOU FIND NO POWER AT THE FUEL SYSTEM CONTROL MODULE, AT THE DARK GREEN/WHITE WIRE, MOVE TO THE POWERTRAIN CONTROL MODULE. AT THE POWERTRAIN CONTROL MODULE, CHECK PIN 50, IN THE BLACK CONNECTOR, FOR 12 VOLTS WITH THE KEY ON, FROM THE DARK GREEN/WHITE WIRE.
IF YOU FIND POWER AT THE POWERTRAIN CONTROL MODULE, LOCATE THE BREAK IN THE WIRE TO REPAIR. IF NO POWER IS FOUND AT THE POWERTRAIN CONTROL MODULE, REPLACE WITH PROGRAMMED UNIT.
IF YOU CHECK YOUR VEHICLE WITH A SCAN TOOL, THE MOST COMMON BAD FUEL SYSTEM CONTROL MODULE ERROR CODE IS P069E. (FUEL SYSTEM CONTROL MODULE REQUEST MIL ILLUMINATION)
| Pin1- | 3 BLK | GROUND |
| pin2-4 | – | NA |
| pin5- | GY | LOW REF |
| Pin6- | TN | HIGH SPEED LAN- |
| Pin7- | TN/BK | HIGH SPEED LAN+ |
| Pin8-9 | – | NA |
| Pin10- | pU | FUEL LINE PRESSURE SIGNAL |
| Pin11-12 | – | NA |
| Pin13- | D-GN/WH | FP RELAY CONTROL – PRIMARY |
| PIN14- | – | NA |
| PIN15- | PK | IGN 1 VOLTAGE |
| PIN16- | PK | LOW REF |
| PIN17- | L-BU | SERIAL DATA ENABLE 12+ |
| PIN18-20 | – | NA |
| PIN21- | TN | HIGH SPEED LAN- |
| PIN22- | TN/BK | HIGH SPEED LAN+ |
| PIN23-31 | – | NA |
| PIN32- | RD/WH | BATTERY POSITIVE VOLTAGE |
| PIN33-35 | – | NA |
| PIN36- | BN | 5-VOLT REF |
| PIN37-43 | – | NA |
| PIN44- | GY | FSCM SHIELD EXT |
| PIN45-46 | – | NA |
| PIN47- | GY | FUEL PUMP SUPPLY VOLTAGE |