DTC P0073: Ambient Temp Sensor High: Testing
- Turn ignition on, engine not running. With the DRBIII®, read the Ambient Temperature Sensor voltage. Is the voltage above 4.8 volts? If yes, go to next step. If no, go to step 7.
- Turn the ignition off. Disconnect the Ambient Temperature Sensor harness connector. Measure the voltage of the Ambient Temperature Sensor Signal circuit in the Ambient Temperature Sensor harness connector. Is the voltage above 5.2 volts? If yes, repair the short to battery voltage in the Ambient Temperature Sensor Signal circuit. If no, go to next step.
- Turn the ignition off. Connect a jumper wire between the Ambient Temperature Sensor Signal circuit and the Sensor Ground circuit in the Ambient Temperature Sensor harness connector. Turn ignition on, engine not running. With the DRBIII®, read Ambient Temperature Sensor voltage. Is the voltage below 1.0 volt? If yes, replace the Ambient Temperature Sensor. If no, go to next step.
- Turn the ignition off. Disconnect the PCM harness connectors. Measure the resistance of the Ambient Temperature Sensor Signal circuit from the Ambient Temperature Sensor harness connector to the appropriate terminal of the Miller Special Tool. Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the open in the Ambient Temperature Sensor Signal circuit.
- Measure the resistance of the Sensor Ground circuit from the Ambient Temperature Sensor harness connector to the appropriate terminal at the Miller Special Tool. Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the open in the Sensor Ground circuit.
- There are no possible causes remaining, replace PCM. Program the new PCM. See PROGRAMMING .
- The conditions that set the DTC are not present at this time. The following may help in identifying the intermittent condition. With the engine running at normal operating temperature, monitor the DRBIII® parameters related to the DTC while wiggling the wiring harness. Look for parameter values to change and/or a DTC to set. Review the DRBIII® Freeze Frame information. If possible, try to duplicate the conditions under which the DTC was set. Refer to any Technical Service Bulletins (TSB) that may apply. Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or partially broken wires. Visually inspect the related wiring harness connectors. Look for broken, bent, pushed out, or corroded terminals. Were any of the above conditions present? If yes, repair as necessary. If no, test is complete.
CAUTION:
Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal-to-pin connection. Use Miller Special Tool (8815) when performing diagnosis at PCM harness connectors.
NOTE:
Before continuing, check the PCM harness connectors for corrosion, damage or terminal push out. Repair as necessary.
WARNING:
When the engine is operating, do not stand in a direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing.