DTC P1478: Battery Temp Sensor Volts Out Of Limit: Testing
NOTE:
If DTC P1492 or P1493 are also present, perform diagnosis for those DTCs first.
- Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and equal to zero, go to next step. If GOOD TRIP counter is not displayed and equal to zero, go to step 7 .
- Turn ignition off. Disconnect ambient temperature sensor harness connector. See Fig 1 . Turn ignition on. Using scan tool, read ambient temperature sensor voltage. If voltage is more than 4.6 volts, go to next step. If voltage is 4.6 volts or less, go to step 4 .
- Turn ignition off. Connect a jumper wire between ambient temperature sensor harness connector terminals. Turn ignition on. Using scan tool, read ambient temperature sensor voltage. If voltage is one volt or more, go to next step. If voltage is less than one volt, replace ambient temperature sensor.
- Reconnect ambient temperature sensor harness connector. Start engine and let it idle. Measure voltage drop in sensor ground circuit (Black/Light Blue wire) by backprobing between ambient temperature sensor connector and terminal No. 43 at PCM C2 connector. See Figure and Figure . If voltage drop is less than .1 volt, go to next step. If voltage drop is .1 volt or more, repair high resistance in sensor ground circuit.
- With engine idling, measure voltage drop in ambient temperature sensor signal circuit (Violet/Light Green wire) by backprobing between ambient temperature sensor connector and terminal No. 52 at PCM C2 connector. If voltage drop is less than .1 volt, go to next step. If voltage drop is .1 volt or more, repair high resistance in ambient temperature sensor signal 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.