Diagnostic Trouble Code (DTC) Information

Diagnostic trouble code (DTC) information CEM-3F91

Condition




Central electronic module (CEM) checks the fuel pump relay, and activates it, when an approved check has been made by the system for Immobilizer. The fuel pump relay is located internally in the Central electronic module (CEM). The fuel pump relay sends voltage feed to the fuel pump when the relay is activated.
If Central electronic module (CEM) detects that the output to the fuel pump is short-circuited to voltage, the diagnostic trouble code is generated.
The diagnostic trouble code (DTC) can be diagnosed in ignition position II and if the fuel pump relay is activated at the same time.

Note!
Applies to vehicles to and incl. model year 2006
- When troubleshooting, the fuel pump may not be supplied with voltage by an external power source without first disconnecting the connector to the Central electronic module (CEM). If the connector is not loosened and the fuel pump is supplied with voltage, this can lead to failure of an internal ground conductor in the Central electronic module (CEM).

Applies to vehicles from and incl. model year 2007
- The case with the ground cable described above does not apply to Central electronic module (CEM) from and incl. model year 2006. This diagnostic trouble code can be generated if the cable for voltage feed to the fuel pump has an open circuit or if the fuel pump is not connected.

The following applies to vehicles with fuel pump module (PEM):
Central electronic module (CEM) checks the voltage feed to the fuel pump module. The Central electronic module (CEM) activates the voltage supply to the fuel pump control module after the checks carried out by the function for the immobilizer have been approved. The diagnostic trouble code (DTC) is stored if the central electronic module (CEM) registers that the voltage in the signal cable is too high.
The diagnostic trouble code (DTC) can be diagnosed in ignition position II and if the relay for power supply to the fuel pump control module is not activated.

Substitute value
- None.

Possible source
- The cable for voltage feed to the fuel pump module is short-circuited to voltage.

Note! Applies to vehicles to and incl. model year 2006If the signal cable has been short-circuited to voltage, there is a risk of failure of an internal ground conductor on one of the circuit boards in the Central electronic module (CEM). This may lead to the relay for 15-feed, on Central electronic module (CEM), not working as intended. A result of incorrect function of 15-feed may be, e.g., that diagnostic trouble codes are generated for the seat heater in front seats and also that the communication with Brake control module (BCM) doe not work when the engine is on (BCM is not supplied with voltage when the 15-relay is not grounded). The malfunction may have different effects in different vehicles, depending on the vehicle's configuration (which units that are supplied via 15-feed), but also depends on where the ground conductor has failed.

Fault symptom[s]
- Battery discharges