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Home >> Jeep >> 2005 >> Wrangler Rubicon, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 556 (DTCS U1412 To U1418, Symptom Tests, Powertrain Verification Test & Schematics And Diagrams) >> Diagnosis And Testing >> *No Response With A No Start Condition >> 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)  (A209) PCM FUSED B+ CIRCUIT 
    Fig 1: Checking PCM Fused B+ Circuit
    GC0003077Courtesy of DAIMLERCHRYSLER CORP.
    NOTE: The scan tool and cable must be operating properly for the results of this test to be valid.
    NOTE: Make sure the ignition switch was on while trying to communicate with the PCM.

    Turn the ignition off.

    Disconnect the C1 PCM harness connector.

    CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

    Using a 12-volt test light connected to ground probe the appropriate terminal of special tool #8815.

    Does the test light illuminate brightly? 

    Yes 

    1. Go To step  2).

    No 

    1. Repair the open or short to ground in the (A209) Fused B+ circuit. Inspect and replace fuses as necessary.
    2. Perform POWERTRAIN VERIFICATION TEST .
  2. 2)  (F942), (F1), (F26) PCM FUSED IGNITION SWITCH CIRCUITS 
    Fig 2: Checking PCM Ignition Circuits
    GC0003020Courtesy of DAIMLERCHRYSLER CORP.

    Using a 12-volt test light connected to ground, probe the (F942), (F1), (F26) PCM Fused Ignition Switch Output circuit in the appropriate terminals of special tool #8815.

    Does the test light illuminate brightly? 

    Yes 

    1. Go To step  3).

    No 

    1. Repair the (F942), (F1), (F26) Ignition Switch Output circuit. Inspect and replace fuses as necessary.
    2. Perform POWERTRAIN VERIFICATION TEST .
  3. 3)  (Z130), (Z816) PCM GROUND CIRCUITS 
    Fig 3: Checking PCM Ground Circuits
    GC0003078Courtesy of DAIMLERCHRYSLER CORP.

    Using a 12-volt test light connected to battery voltage, probe the (Z130), (Z816) PCM ground circuits in the appropriate terminals of special tool #8815.

    Does the test light illuminate brightly? 

    Yes 

    1. Go To step  4).

    No 

    1. Repair the (Z130), (Z816) PCM ground circuits.
    2. Perform POWERTRAIN VERIFICATION TEST .
  4. 4)  (F855) 5-VOLT SUPPLY CIRCUIT 
    Fig 4: Checking 5-Volt Supply Circuit
    GC0002827Courtesy of DAIMLERCHRYSLER CORP.

    Turn the ignition off.

    Connect the PCM harness connectors.

    Disconnect the Crankshaft Position Sensor harness connector.

    Ignition on, engine not running.

    Measure the voltage on the (F855) 5-volt Supply circuit.

    Is the voltage between 4.5 and 5.2 volts? 

    Yes 

    1. Go To step  5).

    No 

    1. Go To step  6).
  5. 5)  CKP SENSOR 
    Fig 5: Checking 5-Volt Supply Circuit
    GC0002827Courtesy of DAIMLERCHRYSLER CORP.

    Turn the ignition off.

    Disconnect the TP Sensor harness connector.

    Ignition on, engine not running.

    Measure the voltage on the (F855) 5-volt Supply circuit in the TP Sensor harness connector.

    Is the voltage between 4.5 and 5.2 volts? 

    Yes 

    1. If communication is available with a PCM on a like vehicle, replace and program the Powertrain Control Module per Service Information.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Replace the Crankshaft Position Sensor.
    2. Perform POWERTRAIN VERIFICATION TEST .
  6. 6)  (F855) 5-VOLT SENSOR OPEN/SHORTED 
    Fig 6: Checking 5-Volt Supply Circuit
    GC0027052Courtesy of DAIMLERCHRYSLER CORP.
    Fig 7: Checking 5-Volt Supply Circuit
    GC0002683Courtesy of DAIMLERCHRYSLER CORP.

    Turn the ignition off.

    Disconnect the TP Sensor/Throttle Body harness connector.

    Ignition on, engine not running.

    Measure the voltage on the (F855) 5-volt Supply circuit.

    Disconnect all the sensors that use the (F855) 5-volt Supply circuit.

    Did the voltage return to 4.5 to 5.2 volts when disconnecting any of the sensors. 

    Yes 

    1. Replace the sensor that is pulling down the (F855) 5-volt supply.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go To step  7).
  7. 7)  (F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND 

    Turn the ignition off.

    Disconnect PCM harness connectors.

    Disconnect all the sensors that share the (F855) 5-volt Supply circuit.

    Measure the resistance between ground and the (F855) 5-volt Supply circuit at one of the sensor harness connectors.

    Is the resistance below 100 ohms? 

    Yes 

    1. Repair the short to ground in the (F855) 5-volt Supply circuit.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go To step  8).
  8. 8)  (F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND 

    Disconnect all the sensors that share the (F856) 5-volt Supply circuit.

    Measure the resistance between ground and the (F856) 5-volt Supply circuit at one of the sensor harness connectors.

    Is the resistance below 100 ohms? 

    Yes 

    1. Repair the short to ground in the (F856) 5-volt Supply circuit.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go To step  9).
  9. 9)  PCM 
    NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

    Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

    Were there any problems found? 

    Yes 

    1. Repair as necessary.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Replace and program the Powertrain Control Module per Service Information.
    2. Perform POWERTRAIN VERIFICATION TEST .
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