Circuit/System Testing

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.
2. Verify that DTC U18xx is not set in any module listed.
   • ECM
   • HPCM
   • SDGM

• If DTC U18xx is set in any of the above modules, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

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.
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.