P154C
DTC P154C
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provide an overview of each diagnostic category.
DTC Descriptor
DTC P154C
- Intake Air (IA) Heater Current Signal Circuit.
Diagnostic Fault Information
Circuit/System Description
The intake air heater (IAH) 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 IAH on when the engine coolant temperature is below 40°C (104°F). Power to the IAH is supplied by the battery positive voltage circuit. The IAH is connected to the GPCM by the following circuits. If there is a fault on any of these circuits a DTC will set.
* The IAH temperature signal circuit
* The IAH command 1 circuit
* The IAH command 2 circuit
* The IAH voltage signal circuit
* The IAH current signal circuit
* The IAH feedback signal circuit
Conditions for Running the DTC
* The IAH is commanded ON.
* The IAH battery voltage is more than 6.9 volts.
* GPCM ignition voltage is more than 6.9 volts.
* DTC 154C runs continuously when the above conditions are met.
Conditions for Setting the DTC
The GPCM detected an open, short to ground or short to battery on the IAH current signal circuit.
Action Taken When the DTC Sets
DTC P154C is a Type B DTC.
Conditions for Clearing the DTC
DTC P154C is a Type B DTC.
Reference Information
Schematic Reference
Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
Observe the following with a scan tool.
1. The IA Heater Driver Open parameter should display OK.
2. Engine running, observe the DTC information with a scan tool. DTC P154C should not set.
3. 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.
1. Test the IAH current signal circuit between IAH terminal 4 X1 and GPCM terminal 29 X2 for an open, a short to ground, or a short to voltage:
2. Ignition OFF, disconnect the X1 harness connector of the IAH. Connect any other circuits that were previously disconnected.
Important: Set the DMM to the 4V DC hertz scale.
3. Turn ON the ignition. With a DMM measure between command 2 circuit terminal 3 of the connector and a good ground for 0.78-1.1 Hz.
• If the DMM does not measure between 0.78-1.1 Hz, replace the GPCM.
Important:
* Do not supply 12 volts to terminal 2 on the IAH for more than 20 seconds.
* Set the DMM to the 4V DC hertz scale.
4. Turn OFF the ignition. Install a jumper wire between temperature signal circuit terminal 1 of the connector and the corresponding terminal on the IAH.
5. Install a jumper wire between the IAH harness command 2 circuit terminal 3 of the connector and the corresponding terminal on the IAH.
6. Supply 12 volts to terminal 2 on the IAH.
7. Turn ON the ignition. Measure for 1 hertz on terminal 4 at the IAH.
• If 0.7-1.1 hertz is measured on terminal 4, replace the GPCM.
• If 0.7-1.1 hertz is not measured on terminal 4, replace the IAH.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Intake Air Heater Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for GPCM replacement, setup, and programming