P1799

DTC P1799: Problem in Intake Air Temperature Sensor Circuit

NOTE: Record all freeze data and review General Troubleshooting Information before you troubleshoot.

1. Check whether the OBD II scan tool indicates a code for the intake air temperature (IAT) sensor in the fuel and emissions system.
Does the OBD II scan tool indicate a code for IAT sensor?
YES-Do the DTC Troubleshooting for the IAT sensor circuit. Recheck for DTC P1799 after troubleshooting.
NO-Go to step 2.
2. Turn the ignition switch OFF.
3. Disconnect TCM connectors A (31P) and C (17P).
4. Turn the ignition switch ON (II).





5. Measure the voltage between TCM connector terminals C14 and A23 or A24.
Is thereabout 5 V?
YES-Go to step 6.
NO-Repair open or short in VREF wire between TCM connector terminal C14 and the ECM.





6. Measure the voltage between TCM connector terminals C8 and A23 or A24.
Is there 0.1 - 4.8 V?
YES-Check the terminal fit at TCM connector terminal C8. If the connection is OK, update the TCM if it does not have the latest software, or substitute a known-good TCM, then recheck. If the symptom/indication goes away with a known-good TCM, replace the original TCM.
NO- Repair open in the wire between TCM connector terminal C8 and the IAT sensor.