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Circuit/System Testing

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Initial Test

  1. Ignition ON, verify 4-6 volts between the PTLAN circuits of the DLC connector terminals 3 and 11.
    • If not within the specified range, refer to Active U0074 Test below.
  2. Verify that DTC U18xx is not set in any module listed.
    • ECM
    • HPCM
    • SDGM

Active U0074 Test

  1. With the ignition OFF, disconnect the module/component harness connectors listed below one at a time. After each disconnect and with the ignition ON, test for 4-6 volts between PTLAN circuits of DLC connector terminals 3 and 11 until the voltage is within specified range.
    1. Data link resistor 2 - X1
    2. Yaw rate and lateral acceleration sensor - X1
    3. Engine control module (ECM) - X3
    4. Hybrid powertrain control module (HPCM) - X1
    5. Accessory DC power control module (APM) - X1
    6. Electronic brake control module (EBCM) - X1
    7. Serial data gateway module (SDGM) - X1
    • If all module/components are disconnected and not within the specified range, test all 4 PTLAN circuits of SDGM connector X1 for a short between them, short to voltage, or a short to ground. If the circuits test normal, replace the SDGM.
    2. IMPORTANT: If either the data link resistor or the ECM is the module/component disconnected before voltage at the DLC terminals is within the specified range no further testing is necessary, replace the last module/component disconnected.
  2. Test for infinite resistance between both PTLAN circuits of the last module disconnected that lead to the previously disconnected module/component.
    • If less than the specified value, test the circuits for a short together.
  3. Test for infinite resistance between ground and both PTLAN circuits of the last module disconnected that lead to the previously disconnected module/component.
    • If less than the specified value, test the circuit for a short to ground.
  4. Test for less than 1 volt between ground and both PTLAN circuits of the last module disconnected that lead to the previously disconnected module/component.
    • If greater than the specified range, test the circuit for a short to voltage.
  5. If the circuits test normal, replace the last module disconnected.
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