LEMON Manuals: Even more car manuals for everyone
Home >> Jeep >> 2021 >> Grand Cherokee L Laredo, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 25 (8HP75 Automatic Transmission - DTCS P1D79-00 To U1489) >> Diagnosis And Testing >> U0074-00: Dedicated Powertrain (D-Pt) Can Bus Off >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different variant/trim than selected.
  1. READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR DTC TO RETURN 
    NOTE:

    For vehicle communication problems, use the scan tool to refer to the Network Review Screen. The screen depicts a high level view of the vehicle network. Fault and problem areas appear in red. Selecting any of the network components allows access to the source of the problem.

    1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
    2. With the scan tool, run a vehicle Scan Report, or record the Environmental Data related to the DTCs.
    3. With the scan tool, erase all DTCs.
    4. Turn the ignition off for a minimum of 10.0 seconds.
    5. Turn the ignition on.
    6. Using the recorded Environmental Data and the When Monitored Conditions above, operate the vehicle in the conditions that set the DTC.
    7. With the scan tool, read DTCs.

    Did the DTC return?

    Yes 

    • Go To  2

    No 

  2. CHECK THE PRIVATE CONTROLLER AREA NETWORK (CAN) CIRCUIT VOLTAGE 
    1. Turn the ignition off.
    2. Disconnect the TCM harness connector.
    3. Turn the ignition on.
    4. Measure the voltage between ground and the (D310) Private CAN (+) circuit at the TCM harness connector.
    5. Measure the voltage between ground and the (D309) Private CAN (-) circuit at the TCM harness connector.

      Is the voltage between 2.4 and 2.6 volts for each circuit?

      Yes 

      • Using the schematics as a guide, check the Transmission Control Module (TCM) connector and all related in-line connector terminals for corrosion, damage, or pushed out terminals. Pay particular attention to the power and ground circuits. If no problems are found, replace the TCM in accordance with the Service Information. Refer to MODULE, TRANSMISSION CONTROL (TCM), REMOVAL AND INSTALLATION .
      • Perform the TCM VERIFICATION TEST. Refer to TRANSMISSION VERIFICATION TEST .

      No 

      • Go To  3
  3. CHECK THE (D310) PRIVATE CAN (+) CIRCUIT FOR AN OPEN CIRCUIT OR HIGH RESISTANCE 
    1. Turn the ignition off.
    2. Disconnect the ESM harness connector.
    3. Measure the resistance of the (D310) Private CAN (+) circuit between the ESM harness connector and the TCM harness connector.

    Is the resistance below 3.0 Ohms?

    Yes 

    • Go To  4

    No 

    • Repair the (D310) Private CAN (+) circuit for an open or high resistance.
    • Perform the TCM VERIFICATION TEST. Refer to TRANSMISSION VERIFICATION TEST .
  4. CHECK THE (D309) PRIVATE CAN (-) CIRCUIT FOR AN OPEN CIRCUIT OR HIGH RESISTANCE 
    1. Measure the resistance of the (D309) Private CAN (-) circuit between the ESM harness connector and the TCM harness connector.

    Is the resistance below 3.0 Ohms?

    Yes 

    • Go To  5

    No 

    • Repair the (D309) Private CAN (-) circuit for an open or high resistance.
    • Perform the TCM VERIFICATION TEST. Refer to TRANSMISSION VERIFICATION TEST .
  5. CHECK THE (D310) PRIVATE CAN (+) CIRCUIT FOR A SHORT TO GROUND 
    1. Check for continuity between ground and the (D310) Private CAN (+) circuit at the TCM harness connector.

      Is there continuity between ground and the (D310) Private CAN (+) circuit?

    Yes 

    No 

    • Go To  6
  6. CHECK THE (D309) PRIVATE CAN (-) CIRCUIT FOR A SHORT TO GROUND 
    1. Check for continuity between ground and the (D309) Private CAN (-) circuit at the TCM harness connector.

    Is there continuity between ground and the (D309) Private CAN (-) circuit?

    Yes 

    No 

    • Go To  7
  7. CHECK THE (D310) PRIVATE CAN (+) CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT 
    1. Check for continuity between the (D310) Private CAN (+) circuit and all other circuits at the TCM harness connector.

    Is there continuity between the (D310) Private CAN (+) circuit and any other circuit?

    Yes 

    • Repair the (D310) PRIVATE CAN (+) circuit for a short to another circuit.
    • Perform the TCM VERIFICATION TEST. Refer to TRANSMISSION VERIFICATION TEST .

    No 

    • Go To  8
  8. CHECK THE (D309) PRIVATE CAN (-) CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT 
    1. Check for continuity between the (D309) Private CAN (-) and all other circuits at the TCM harness connector.

    Is there continuity between the (D309) Private CAN (-) and any other circuit?

    Yes 

    No 

    • Using the schematics as a guide, check the Electronic Shift Module (ESM) connector and all related in-line connector terminals for corrosion, damage, or pushed out terminals. Pay particular attention to the power and ground circuits. If no problems are found, replace the ESM in accordance with the Service Information. Refer to MODULE, ELECTRONIC SHIFT (ESM), REMOVAL AND INSTALLATION .
    • Perform the TCM VERIFICATION TEST. Refer to TRANSMISSION VERIFICATION TEST .
scientia non olet · About LEMON Manuals