Got a P1238 code, car will not go into boost, help !
- Thread starter hmg_57
- Start date
Here's what I found on another website.
P1238 - Fuel Pump Secondary Circuit Malfunction See DTC P1237. P1238 is identical to P1237 except P1238 will not illuminate the MIL.
P1237 - Fuel Pump Secondary Circuit Malfunction Note: For LS6/LS8, the FPDM functions are incorporated in the rear electronics module (REM). Also, the REM does not use a FPM circuit. Diagnostic information will be set through SCP.
Indicates that the FPDM has detected a fuel pump secondary circuit fault. The FPDM will send a message to the PCM through the FPM circuit, indicating that this failure has been detected. The PCM will set the DTC when the message is received.
Open or shorted FP PWR circuit
Open FP RTN circuit to FPDM
Open or shorted circuit in the fuel pump
Locked fuel pump rotor
Damaged FPDM
For LS6/LS8, circuits associated with the Fuel Pump relay
The FPDM sends a 75% duty cycle (750 msec ON, 250 msec OFF) through the FPM circuit to the PCM while the fault is being detected by the FPDM. If the fault is no longer detected, the PCM will return to sending an "all OK" (50% duty cycle) message to the PCM. The PCM will keep P1237 stored in Continuous Memory.
The FPDM controls pump speed by supplying a "variable" ground on the RTN circuit.
I don't know what is the LS6 / LS8 they refer to and I do have the MIL even though it says P1238 will not illuminate it.
Blown fuse would obviously create an open condition, will check and report back any findings.
P1238 - Fuel Pump Secondary Circuit Malfunction See DTC P1237. P1238 is identical to P1237 except P1238 will not illuminate the MIL.
P1237 - Fuel Pump Secondary Circuit Malfunction Note: For LS6/LS8, the FPDM functions are incorporated in the rear electronics module (REM). Also, the REM does not use a FPM circuit. Diagnostic information will be set through SCP.
Indicates that the FPDM has detected a fuel pump secondary circuit fault. The FPDM will send a message to the PCM through the FPM circuit, indicating that this failure has been detected. The PCM will set the DTC when the message is received.
Open or shorted FP PWR circuit
Open FP RTN circuit to FPDM
Open or shorted circuit in the fuel pump
Locked fuel pump rotor
Damaged FPDM
For LS6/LS8, circuits associated with the Fuel Pump relay
The FPDM sends a 75% duty cycle (750 msec ON, 250 msec OFF) through the FPM circuit to the PCM while the fault is being detected by the FPDM. If the fault is no longer detected, the PCM will return to sending an "all OK" (50% duty cycle) message to the PCM. The PCM will keep P1237 stored in Continuous Memory.
The FPDM controls pump speed by supplying a "variable" ground on the RTN circuit.
I don't know what is the LS6 / LS8 they refer to and I do have the MIL even though it says P1238 will not illuminate it.
Blown fuse would obviously create an open condition, will check and report back any findings.
GT Charlie
Member
The most common cause of your concern is a faulty relay. Just swap the fuel pump 2 relay with a wiper relay below it ( they are the same) and recheck to see if your concern is still present. If concern is still present It will not be so simple to diagnose. Most likely the pump or an overheated wire connection. The fuse for the relay is in the same aux fuse box #2 15 amp.
nz05gt
GT Owner
Just so you know the fuel pumps are accessable through the centre tunnel under the console/handbrake there is an access hole.
:cheers
Neil
To follow up on this issue, I brought the car to the dealer and it turns out one of the fuel pumps was dead. We didn't open it so I'll never know if it was an electrical or mechanical problem but the car is back on the road. For the record, the GT only had 700 miles when the pump died.
Thanks for the help guys, love this community !!
Thanks for the help guys, love this community !!