Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P0640: Intake Air (IA) Heater Control CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage |
|---|---|---|---|
IA Heater Temperature Signal | -- | P154D | P154D |
IA Heater Command 2 | P154B | P154B | P154B |
IA Heater Voltage Signal | P154B | P154B | P154B |
IA Heater Command 1 | P154B | P154B | P0640 |
IA Heater Current Signal | P154C | P154C | P154C |
IA Heater Feedback Signal | P154A | P154A | P154A |
IA Heater Battery Positive Voltage | P154B | P154B | -- |
Circuit/System Description
The intake air (IA) heater is located in the air inlet tube and is used to warm the incoming air to aid in starting the engine and for proper cylinder combustion. The glow plug control module (GPCM) will command the IA heater ON when the engine coolant temperature is below 40°C (104°F). The power to the IA heater is supplied by the battery positive voltage circuit. The IA heater is connected to the GPCM by the following circuits:
| • | The IA heater temperature signal circuit |
| • | The IA heater command 1 circuit |
| • | The IA heater command 2 circuit |
| • | The IA heater voltage signal circuit |
| • | The IA heater current signal circuit |
| • | The IA heater feedback signal circuit |
If there is a fault on any of these circuits, a DTC will set.
Conditions for Running the DTC
| • | The IA heater is commanded OFF. |
| • | DTC P0640 runs continuously when the above condition is met. |
Conditions for Setting the DTC
The digital response signal is high and the command 2 signal is activated.
Action Taken When the DTC Sets
DTC P0640 is a Type B DTC.
Conditions for Clearing the DTC
DTC P0640 is a Type B DTC.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
- Ensure that the IA heater Command 1 CKT Short to Voltage parameter displays OK.
- Ensure that the IA heater can be commanded ON.
- Engine running, observe the DTC information with a scan tool. DTC P0640 should not set.
- Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
- Disconnect the IA heater
- Turn ON the ignition. Test the IA heater command 1 circuit terminal 2 for less than 12 volts.
- If the command 1 circuit tests normal, replace the IA heater.
| ⇒ | If greater than 12 volts, test the command 1 circuit for a short to voltage. If the circuit tests normal, replace the glow plug control module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for GPCM replacement, setup, and programming |
