Ambient Air Temperature Sensor, Checking
Special tools and workshop equipment required
- Multimeter.
- Wiring diagram.
Test procedure
-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK
Start diagnosis
-- Connect the scan tool.
-- Engine MUST be at room temperature.
-- Turn the ignition switch ON.
-- Using the scan tool, check the ambient air temperature:
| Diagnostic text | Specified value | |||
|---|---|---|---|---|
| Ambient Air Temperature (AAT) Sensor | approx. ambient air temperature | |||
-- Turn the ignition switch OFF.
If the specified value was obtained:
-- Fault may be intermittent. Check for proper connection, damaged wiring or loose terminals.
The reading will default to 419 °F if the circuit is open or shorted to ground. The display on the cluster will read 3 dashes.
If the specified value was Not obtained:
Checking internal resistance
-- Disconnect the Ambient Air Temperature Sensor -G17- electrical harness connector.
-- Using a multimeter, check the Ambient Air Temperature Sensor -G17- terminals 1 to 2 for resistance.
Use the chart below for the specified values:
Specified values:
| AAT Temperature vs Resistance | ||
| Temp (C) | min. value ohms | max. value ohms |
| - 40 | 31811 | 37560 |
| - 35 | 22941 | 26863 |
| - 25 | 12415 | 14289 |
| - 15 | 6958 | 7880 |
| - 5 | 4036 | 4495 |
| 0 | 3120 | 3442 |
| 5 | 2422 | 2655 |
| 15 | 1519 | 1623 |
| 25 | 968 | 1031 |
| 35 | 629 | 676 |
| 45 | 419 | 455 |
| 55 | 286 | 314 |
| 65 | 195 | 217 |
| 75 | 136 | 155 |
If the specified values were Not obtained:
-- Replace the Ambient Air Temperature Sensor -G17-. Refer to the Repair information.
If the specified values are obtained, continue the test according to the following table:
Checking wiring
-- Turn the ignition switch ON.
-- Connect a multimeter to terminals 1 and 2 of the Ambient Air Temperature Sensor -G17- electrical harness connector.
Specified value: near 5.02 V
-- Turn the ignition switch OFF.
If the specified value was Not obtained:
-- Remove the Instrument Cluster. Refer to the Repair information.
-- Disconnect the Instrument Cluster harness.
-- Using a multimeter, check the Ambient Air Temperature Sensor -G17- electrical harness connector to the Instrument Cluster electrical harness connector for an open circuit or a short, refer to the chart below.
| Ambient Air Temperature Sensor -G17- electrical harness connector terminals: | Instrument Cluster -J285- electrical connector T32 terminals: |
|---|---|
| 1 | 20 |
| 2 | 19 |
Specified value: 1.5 Ω max.
If the specified value was Not obtained:
-- Check the wiring for an open, high resistance or short circuit to Battery positive or ground.
-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
-- If necessary, repair the faulty wiring connection.
If the specified value was obtained:
Replace the Instrument Cluster. Refer to the Repair information.
Final procedures
After the repair work, the following work steps must be performed in the following sequence:
- Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
- If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
- If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .