DTC P1493: Ambient/Batt Temp Sen Volts Too Low: Testing

Turn ignition on. Using scan tool, read ambient temperature sensor voltage. If voltage is less than .3 volt, go to next step. If voltage is .3 volt or more, go to step 6 .
Turn ignition off. Disconnect ambient temperature sensor harness connector. See Figure . Turn ignition on. Using scan tool, read ambient temperature sensor voltage. If voltage is one volt or less, go to next step. If voltage is more than one volt, replace ambient temperature sensor.
Turn ignition off. Disconnect PCM harness connectors. See Figure . Measure resistance between ground and signal circuit (Violet/Light Green wire) at ambient temperature sensor harness connector. If resistance is 100 ohms or more, go to next step. If resistance is less than 100 ohms, repair short to ground in Violet/Light Green wire.
Measure resistance between ambient temperature sensor harness connector terminals. If resistance is 100 ohms or more, go to next step. If resistance is less than 100 ohms, repair short between signal circuit and sensor ground circuit.
If no other possible causes are remaining, replace PCM.
Conditions that set DTC are not present at this time. Perform the following to help identify intermittent condition:
- With engine running at normal operating temperature, wiggle related wiring harness while monitoring related parameters on scan tool. If voltage changes or DTC sets while wiggling wiring harness, repair connectors or wiring harness where wiggling caused voltage to change or DTC to set.
- Review freeze frame information on scan tool. Duplicate conditions present when DTC was set.
- Refer to any technical service bulletins that may apply.
- Visually inspect related wiring harness. Check for chafed, pierced, pinched or partially broken wires.
- Visually inspect related wiring harness connectors. Check for broken, bent, pushed out or corroded terminals.
If a problem is found, repair as necessary. If no problems are found, test is complete.