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Error Code P1233 is defined as Fuel Pump Driver Module Disabled Or Off Line. This means the fuel pump is not starting up correctly, which could be caused by problems with the FPDM (fuel pump driver module).
This error code is a generic trouble, meaning it applies to all vehicles equipped with OBD-II system, especially vehicles made since 1996 up to present. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.
Error Code P1233 is set when the fuel pump is not starting up correctly. This could be caused by two primary reasons that interfere with fuel pump startup – the fuel pump relay, or the inertia switch.
The most common symptom and usually the only symptom for this error code is the activation of the Check Engine light and the registration of the error code.
The PCM (Powertrain Control Module, also known as ECM or engine control module in other vehicles makes) monitors the FPM (Fuel Pump Monitor) circuit from the FDPM (Fuel Pump Driver Module). With the key on, the FDPM sends duty cycle signal to the PCM continuously through FPM circuit. If this fails (the PCM stops receiving the duty signal), then the Error Code P1233 will set.
As said earlier, this error code could be caused by a lot of factors. Some of the most common possible causes include:
- IFS (Inertia Fuel Shutoff) switch needs to be reset
- Faulty IFS (Inertia Fuel Shutoff) switch
- Faulty FDPM (Fuel Pump Driver Module)
- Open or shorted FDPM (Fuel Pump Driver Module) harness
- Poor electrical connection in FDPM (Fuel Pump Driver Module) circuit
- Faulty PCM (rare)
How to Check
To check for this code, technicians usually start by checking the fuel pump fuse.
Next, they reset the inertia switch manually.
If both things still don’t work, technicians will check for power at the fuel pump connector. If the connector is not getting power, technicians will pull the fuel pump relay (or change I with another relay with the same part number) or jumper the relay contacts to power the pump.
If that doesn’t fix the problem, technicians will now check for power coming into the relay. If there is sufficient power, they will re-jumper the relay contacts and then check for power coming from the fuse box and straight to the pump.
If the problem persists, technicians will now test the wiring crimp connectors. In some cases, faulty factory crimps at the relay box could be causing this issue.
How to Fix
- Repair or replace faulty fuel pump fuse
- Reset the inertia switch manually
- Repair or replace faulty fuel pump connector
- Repair or replace faulty wirings in the crimp connectors
Faulty PCM is not usually the cause of this error code, but in some occasions, it could because of faulty or outdated PCM.