Diagnostic Test

1) AAT SENSOR VOLTAGE BELOW 0.078 OF A VOLT
NOTE: Diagnose any CAN - C Communication DTCs before continuing.

Ignition on, engine not running.

With a scan tool, read the Ambient Air Temperature Sensor voltage.

Is the voltage below 0.078 of a volt?

Yes
1. Go To 2).
No
1. Refer to INTERMITTENT CONDITION .
2. Perform POWERTRAIN VERIFICATION TEST .
2) CHECKING AAT SENSOR
Turn the ignition off.

Disconnect the Ambient Air Temperature Sensor harness connector.

Ignition on, engine not running.

With a scan tool, read the AAT Sensor voltage.

Is the voltage above 4.6 volts?

Yes
1. Replace the Ambient Temperature Sensor.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To 3).
3) (G31) AAT SIGNAL CIRCUIT SHORTED TO GROUND

Fig 1: Checking Ambient Air Temperature Sensor Signal Circuit Shorted To Ground
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the C2 FCM harness connector.

Measure the resistance between ground and the (G31) AAT Signal circuit in the AAT Sensor harness connector.

Is the resistance below 100 ohms?

Yes
1. Repair the short to ground in the (G31) AAT Signal circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To 4).
4) (G31) AAT SIGNAL CIRCUIT SHORTED TO THE (G931) SENSOR GROUND CIRCUIT

Fig 2: Checking AAT Sensor Signal Circuit Shorted To Ground
Courtesy of DAIMLERCHRYSLER CORP.

Measure the resistance between the (G931) Sensor ground circuit and the (G31) AAT Signal circuit in the AAT Sensor harness connector.

Is the resistance below 5.0 ohms?

Yes
1. Repair the short between the (G931) Sensor ground circuit and the (G31) AAT Signal circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To 5).
5) FRONT CONTROL MODULE
NOTE: Before continuing, check the FCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

Were there any problems found?

Yes
1. Repair as necessary.
2. Perform BODY VERIFICATION TEST - VER 1 .
No
1. Replace and program the Front Control Module per Service Information.
2. Perform BODY VERIFICATION TEST - VER 1 .