Diagnostic Test

1) IAT SENSOR VOLTAGE ABOVE 4.98 VOLTS
Ignition on, engine not running.

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

Is the voltage above 4.98 volts?

Yes
1. Go To 2).
No
1. Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to ENGINE - STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
2) IAT SENSOR

Fig 1: CHECKING IAT SENSOR
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the Intake Air Temperature Sensor harness connector.

Connect a jumper wire between the (K21) IAT Signal circuit and the (K900) Sensor ground circuit in the IAT Sensor harness connector.

Ignition on, engine not running.

With a scan tool, read the IAT Sensor voltage.

Is the voltage below 1.0 volt with the jumper wire installed?

Yes
1. Replace the IAT Sensor.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to ENGINE - STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
No
1. Go To 3).
  NOTE: Remove the jumper wire before continuing.
3) (K21) IAT SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE

Fig 2: MEASURING VOLTAGE AT THE IAT SIGNAL CIRCUIT
Courtesy of DAIMLERCHRYSLER CORP.

Ignition on, engine not running.

Measure the voltage on the (K21) IAT Signal circuit in the IAT Sensor harness connector.

Is the voltage above 5.2 volts?

Yes
1. Repair the short to battery voltage in the (K21) IAT Signal circuit.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to ENGINE - STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
No
1. Go To 4).
4) (K21) IAT SIGNAL CIRCUIT OPEN

Fig 3: MEASURING RESISTANCE OF THE IAT SIGNAL CIRCUIT
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the PCM harness connector.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

Measure the resistance of the (K21) IAT Signal circuit from the IAT Sensor harness connector to the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?

Yes
1. Go To 5).
No
1. Repair the open in the (K21) IAT Signal circuit.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to ENGINE - STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
5) (K900) SENSOR GROUND CIRCUIT OPEN

Fig 4: MEASURING RESISTANCE OF THE SENSOR GROUND CIRCUIT
Courtesy of DAIMLERCHRYSLER CORP.

Measure the resistance of the (K900) Sensor ground circuit from the IAT Sensor harness connector to the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?

Yes
1. Go To 6).
No
1. Repair the open in the (K900) Sensor ground circuit.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to ENGINE - STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
6) PCM
NOTE: Before continuing, check the PCM 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 the POWERTRAIN VERIFICATION TEST. (Refer to ENGINE - STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
No
1. Replace and program the Powertrain Control Module per Service Information. Refer to MODULE-POWERTRAIN CONTROL and STANDARD PROCEDURE - PCM/ECM/SKREEM PROGRAMMING .
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to ENGINE - STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .