Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Sierra and 2008 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Start the engine and observe the Transmission ISS parameter on the scan tool. Measure the TCM voltage of the ISS reference circuit to ground. Wiggle the engine harness.
- If the value measures near 12-volt, measure the voltage from the ISS 12-volt reference to the ISS low reference circuit.
- If the value is other than 12-volt, test the ISS 12-volt reference for an open or a short to ground. If no condition found, replace TCM.
- Measure the voltage of the ISS 12-volt reference circuit to the ISS low reference circuit.
- If the value is near 12-volt, connect the J 38522 variable signal generator to the ISS signal circuit
- If the value is not 12-volt, check the ISS low reference circuit for an open or a short to voltage.
- Adjust the J 38522
to 12-volt, frequency to 300 Hz and Duty Cycle to 50 percent.
- If the ISS RPM value is near 600 RPM, check the internal harness for an open, short to ground or a short to voltage.
- If the ISS RPM value is not 600 RPM, check the ISS signal circuit for an open, short to ground or a short to voltage.
- Remove the AT ISS sensor. Refer to Oil Pump Disassemble
.
- If all circuit/connections test normal, test or replace the ISS.