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DTC P0071: Ambient Temp Sensor Performance: Testing

  1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0071 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0071 or displayed count is not "0", go to step  6 .
  2. Turn ignition off. Disconnect BTS connector. BTS is located under battery and has a Black 2-pin connector. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, connect a jumper wire between BTS harness connector terminals. Turn ignition on. Using scan tool, read BTS voltage. If voltage is less than one volt, replace BTS. If voltage is one volt or more, go to next step.
  3. Turn ignition off. Reconnect BTS connector. Using a voltmeter, backprobe Black/Light Blue wire between BTS harness connector and terminal A4 at PCM C1 harness connector. See Figure . PCM is located on firewall in right rear corner of engine compartment. Start engine and note voltage reading. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance in Black/Light Blue wire.
  4. Turn ignition off. Using a voltmeter, backprobe Pink/Yellow wire between BTS harness connector and terminal C15 at PCM C3 harness connector. See Figure . Start engine and note voltage reading. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance in Pink/Yellow wire.
  5. At this time, PCM is assumed to be defective. Replace PCM.
  6. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor parameters related to DTC while wiggling connectors and wiring harness. If value changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused value to change. If value does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.
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