P154B
DTC P154B
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 P154B
- Intake Air (IA) Heater Voltage Signal Circuit
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The intake air heater is located in the air inlet tube and is used to warm the incoming air to aid in cylinder combustion during cold weather operation. The engine control module (ECM) sends commands to the glow plug control module to enable or disable the IAH when certain conditions met. The glow plug control module monitors the voltage and feedback circuits of the intake air heater to verify proper operation. If any of the following circuits are open, shorted to voltage, or shorted to ground DTC P154B may set.
* Intake Air Heater Voltage Feedback Signal
* Intake Air Heater Switch On/Off Signal
* Intake Air Heater Heart Beat Signal
Conditions for Running the DTC
* The intake air heater is commanded ON.
* The glow plug control module battery voltage is between 9.5-15 V.
* DTC P154B runs continuously when the above condition is met.
Conditions for Setting the DTC
DTC will set when any of the following conditions exists:
* Intake air heater voltage is greater than 16 V while the glow plug control module voltage is between 9.5-14 V for more than 650 ms.
* Intake air heater voltage is less than 6.9 V while the glow plug control module voltage is between 9.5-16 V for more than 1000 ms.
* Intake air heater signal voltage is greater than 1.5 V after the intake air heater has been commanded OFF for more than 65 ms.
Action Taken When the DTC Sets
DTC P154B is a Type B DTC.
Conditions for Clearing the DTC
DTC P154B is a Type B DTC.
Diagnostic Aids
* A poor intake air heater ground or loose connection on the battery positive voltage circuit may cause this DTC to set.
* This DTC may only occur when the intake air heater is hot.
* The scan tool does not allow the IAH to operate at 100% and may not produce the fault condition. If the DTC is intermittent the most likely cause is the IAH.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)
Description and Operation
Intake Air Heater System Description Description and Operation
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 Control Module References for scan tool information
Circuit/System Verification
1. Engine running.
2. All accessories OFF, measure and record the battery voltage at the battery terminals. The voltage should be between 12.6 and 15.0 V.
• If not between 12.6 and 15.0 V
Refer to Charging System Test Testing and Inspection.
• If between 12.6 and 15.0 V
3. Ignition ON.
4. Verify the scan tool IAH Voltage Status parameter displays OK.
• If parameter does not display OK
Refer to Circuit/System Testing.
• If parameter displays OK
5. Verify the scan tool Intake Air Heater and Ignition 1 voltage parameters closely match.
• If parameters do not closely match
Refer to Circuit/System Testing.
• If parameters closely match
6. Verify the intake air heater can be commanded ON and OFF with a scan tool.
• If the Intake Air Heater cannot be commanded ON and OFF
Refer to Circuit/System Testing.
• If the Intake Air Heater can be commanded ON and OFF
7. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
• If DTC resets
Refer to Circuit/System Testing.
• If DTC does not reset
8. All OK.
Circuit/System Testing
Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
1. Measure and record the voltage between the Battery Positive Voltage circuit terminal 1 X2 at the intake air heater and ground.
• If voltage is not B+
Repair the open or high resistance in the Battery Positive Voltage circuit.
• If voltage is B+
2. Test the following circuits for an open, short to ground, or short to voltage:
* The Intake Air Heater Voltage Feedback Signal circuit between terminal 23 X2 of the glow plug control module and terminal 5 X1 of the intake air heater.
* The Intake Air Heater Switch On/Off Signal circuit between terminal 30 X2 of the glow plug control module and terminal 2 X1 of the intake air heater.
* The Intake Air Heater Heart Beat Signal circuit between terminal 31 X2 of the glow plug control module and terminal 3 X1 of the intake air heater.
• If an open, short to ground, or short to voltage was found
Repair as necessary.
• If no open, short to ground, or short to voltage was found
3. Connect any circuits that were disconnected.
4. Ignition ON.
5. Verify the scan tool displays the IAH Voltage Status parameter as OK.
• If parameter does not display OK
Replace the E24 Intake Air Heater.
• If parameter displays OK
6. Replace the E24 Intake Air Heater and clear the DTC. Road test the vehicle under the conditions to run the DTC. Verify the DTC does not reset. If the DTC resets, replace the K34 Glow Plug Control module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Intake Air Heater Replacement Service and Repair
* Control Module References Control Module References for glow plug control module replacement, programming, and setup