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Circuit/System Testing

WARNING: This page is about a different car, the 2008 Isuzu i-370, 2008 Isuzu i-290, 2008 GMC Canyon, and 2008 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Test for less than 1.0 ohm of resistance between the DLC ground circuit terminal 5 and ground.
    • If greater than the specified range, test the ground circuit for open/high resistance.
  2. Ignition OFF, disconnect the harness connector X 3 at the engine control module (ECM).
  3. Test for less than 1 ohm of resistance between each ground circuit of the ECM and ground.
    • If greater than the specified range, repair the ground circuit for an open/high resistance.
  4. Ignition ON, test for battery voltage between each voltage input circuit of the ECM and ground.
    • If less than specified, test each voltage input circuit of the ECM for a short to ground or open/high resistance, and each voltage output circuit of the ECM for a short to ground. If the circuits test normal, replace the ECM.
  5. Test for infinite resistance between DLC serial data circuit terminal 14 and ground.
    • If less than the specified range, test both serial data circuits for a short to ground. If the circuits test normal, replace the transmission control module (TCM).
  6. Test for 0 volts between DLC serial data circuit terminal 14 and ground.
    • If greater than the specified value, test both serial data circuits for a short to voltage. If the circuits test normal, replace the TCM.
  7. Ignition OFF. Test for less than 1 ohm of resistance between the DLC serial data circuit terminal 14 and the ECM serial data circuit terminal 33.
    • If greater than the specified range, test the serial data circuit for open/high resistance. If the circuits test normal, replace the TCM.
  8. Ignition OFF. Test for less than 1 ohm of resistance between the DLC serial data circuit terminal 6 and the ECM serial data circuit terminal 53.
    • If greater than the specified range, test the serial data circuit for open/high resistance. If the circuits test normal, replace the TCM.
  9. Ignition OFF, disconnect the harness connector at the TCM.
  10. Test for 110-130 ohms between the DLC serial data circuit terminal 6 and terminal 14.
    • If greater than the specified range, replace the terminator resistor.
    • If less than the specified range, test for a short between the + and - serial data circuits. If the circuits test normal, replace the terminator resistor.
  11. Connect the harness connector at the TCM.
  12. Test for 115-125 ohms between the DLC serial data circuit terminal 6 and terminal 14.
    • If less than the specified range, test for a short between the + and - serial data circuits between the TCM and ECM. If the circuits test normal, replace the TCM.
  13. If the circuits test normal, replace the ECM.
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