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Home >> Jeep >> 2005 >> Wrangler Rubicon, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 598 (DTCS B1059 To U0200) >> Diagnosis And Testing >> U0019-Can B Bus (ATC) >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2005 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
  1. 1)  VERIFY DTC U0019-CAN B BUS IS ACTIVE 

    Turn the ignition on.

    With the scan tool, read HVAC DTCs.

    Does the scan tool display active: U0019-CAN B BUS? 

    Yes 

    1. Go To step  2).

    No 

    1. If the DTC is stored, check for an intermittent condition by inspecting the related wiring harness for chaffed, pierced, pinched, and partially broken wires. Also, inspect the related connectors for broken, bent, pushed out, spread, corroded, or contaminated terminals.
    2. Perform BODY VERIFICATION TEST - VER 1 .
  2. 2)  CHECK FOR ACTIVE CAN B BUS RELATED DTCS IN THE FRONT CONTROL MODULE (FCM) 

    With the scan tool, read Front Control Module (FCM) DTCs

    Does the scan tool display any active CAN B BUS related DTCs? 

    Yes 

    1. Diagnose and repair the DTC(s). (Refer to ELECTRICAL/ELECTRONIC CONTROL MODULES - DIAGNOSIS AND TESTING) .

    No 

    1. Go To step  3).
  3. 3)  CHECK (D55) CAN B BUS (+) CIRCUIT FOR AN OPEN 
    Fig 1: Checking CAN B Bus (+) Circuit For Open
    GC0028296Courtesy of DAIMLERCHRYSLER CORP.

    Turn the ignition off.

    Disconnect the negative battery cable.

    Disconnect the A/C Heater Control C1 harness connector.

    Disconnect the Front Control Module (FCM) C1 harness connector.

    Measure the resistance of the (D55) CAN B Bus (+) circuit between the Front Control Module C1 harness connector and the A/C Heater Control C1 harness connector.

    Is the resistance below 2.0 ohms? 

    Yes 

    1. Go To step  4).

    No 

    1. Repair the (D55) CAN B Bus (+) circuit for an open.
    2. Perform BODY VERIFICATION TEST - VER 1 .
  4. 4)  CHECK (D54) CAN B BUS (-) CIRCUIT FOR AN OPEN 
    Fig 2: Checking CAN B Bus (-) Circuit For Open
    GC0028297Courtesy of DAIMLERCHRYSLER CORP.

    Measure the resistance of the (D54) CAN B Bus (-) circuit between the Front Control Module C1 connector and the A/C Heater Control C1 harness connector.

    Is the resistance below 2.0 ohms? 

    Yes 

    1. Replace the A/C Heater Control in accordance with the Service Information.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Repair the (D54) CAN B Bus (-) circuit for an open.
    2. Perform BODY VERIFICATION TEST - VER 1 .
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