Diagnostic Aids

WARNING: This page is about a different car, the 2002 Saturn LW200, 2002 Saturn L200, and 2002 Saturn L100. However, it is still accessible from the selected car via links, so may be relevant.

To locate an intermittent problem, use scan tool to monitor any of the sensors tied to 5-volt reference circuit (A/C pressure sensor, fuel tank pressure sensor and TP sensor). Wiggling wires while watching for a change in any sensor may locate area where a short to ground or short to voltage on 5-volt reference circuit could lie.

If all 3 sensors tied to 5-volt reference circuit set low sensor voltage DTCs, a short to ground probably exists on 5-volt reference circuit.

If DTCs P0453 and P0105 are set, a short to voltage on 5-volt reference circuit may exist. If a short to voltage occurs on 5-volt reference circuit, scan tool will display TP ANGLE 20-30 percent with throttle plate closed, A/C HIGH SIDE PRESSURE will read more than 2.4 volts with A/C off and FUEL TANK PRESSURE will read more than 4 volts.

MAP sensor circuit contains it's own 5-volt reference supply. ECT and IAT circuits are on their own 5-volt reference supply also.

Inaccurate readings will occur if resistance measurements are taken on A/C pressure sensor or fuel tank pressure sensor. These sensors contain an internal amplifier circuit that requires applied voltage to function properly.