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Home >> Jaguar >> 2003 >> XJ8 Base >> Repair and Diagnosis >> External Pages >> Different car >> Section 112 (Module Communications Network) >> Module Communications Network >> Communications Network - Diagnostic Procedures >> Pinpoint Tests >> Pinpoint Test E: DTC P1637; CHECK THE DSCCM SUPPLIES AND GROUNDS

Pinpoint Test E: DTC P1637; CHECK THE DSCCM SUPPLIES AND GROUNDS

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2006 Jaguar XKR, 2006 Jaguar XK8, 2005 Jaguar XKR, 2005 Jaguar XK8, and 2004 Jaguar XKR. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK THE IGNITION SWITCHED POWER SUPPLY TO THE DSCCM 

    Disconnect the DSCCM electrical connector, LF37.

    Turn the ignition switch to the ON position.

    Measure the voltage between LF37, pin 04 (WU) and GROUND.

    Is the voltage less than 10 volts? 

    YES:  REPAIR the circuit between the DSCCM and battery. This circuit includes the engine compartment fuse box, (fuse 4) the ignition positive relay and the high power protection module. For additional information, refer to the wiring diagrams. Test the system for normal operation.

    NO:  Go to step  2.

  2. CHECK THE PERMANENT SUPPLIES TO THE DSCCM 

    Turn the ignition switch to the OFF position.

    Measure the voltage between LF37, pin 01 (NR) and GROUND.

    Measure the voltage between LF37, pin 32 (NW) and GROUND.

    Is either voltage less than 10 volts? 

    YES:  REPAIR the circuit between the DSCCM and battery. This circuit includes the engine compartment fuse box, (fuses 16 and 18) and the high power protection module. For additional information, refer to the wiring diagrams. Test the system for normal operation.

    NO:  Go to step  3.

  3. CHECK THE PERMANENT GROUNDS TO THE DSCCM 

    Measure the resistance between LF37, pin 16 (B) and GROUND.

    Measure the resistance between LF37, pin 47 (B) and GROUND.

    Is either resistance greater than 5 ohms? 

    YES:  REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams. Test the system for normal operation.

    NO:  Go to step  4.

  4. CHECK THE SWITCHED GROUND TO THE DSCCM 

    Close the DSC switch on the center console.

    Measure the resistance between LF37, pin 38 (R) and GROUND.

    Is the resistance greater than 5 ohms? 

    YES:  REPAIR the high resistance circuit. Make sure the switch is closing fully before beginning harness tests. For additional information, refer to the wiring diagrams. Test the system for normal operation.

    NO:  If the CAN tests are satisfactory, contact dealer technical support for advice on possible DSCCM failure.

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