P154A
DTC P154A
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 P154A
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Intake Air (IA) Heater Feedback 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 intake air heater 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 the Intake Air Heater Digital Response Signal circuit does not match the commanded state of the intake air heater or is opened, shorted to voltage or short to ground DTC P154A may set.
Conditions for Running the DTC
* Engine speed is greater than 600 RPM.
* The intake air heater is commanded ON.
* The battery voltage is more than 8.6 V.
* DTCs P154A runs continuously when the above conditions exists.
Conditions for Setting the DTC
The glow plug control module detects an open, short to ground or short to battery voltage on the intake air heater digital response signal circuit for less than 1 s.
Action Taken When the DTC Sets
DTC P154A is a Type B DTC.
Conditions for Clearing the DTC
DTC P154A is a Type B DTC.
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
Glow Plug System Description Glow Plug System Description
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, command the Intake Air Heater ON and OFF, with a scan tool while observing the IAH Feedback Circuit Status parameter.
The IAH Feedback Circuit Status parameter should display OK.
2. 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.
Circuit/System Testing
1. Test the Intake Air Heater Digital Response Signal circuit between the glow plug control module connector X2 terminal 17 and the intake air heater connector X1 terminal 6 X1 of the intake air heater for an open, a short to ground, or a short to voltage.
• If a condition is found, repair as necessary.
2. Ignition OFF, disconnect the intake air heater X1 harness connector. Connect any other circuits that were previously disconnected.
Note:
Set the DMM to the 4V DC hertz scale.
3. Ignition ON, command the intake air heater OFF with a scan tool , measure the frequency between Intake Air Heater Heart Beat Signal circuit terminal 3 and ground, Verify the frequency is within 0.78-1.1 Hz.
• If not within the specified value, replace the K34 glow plug control module.
Note:
* Do not supply 12 volts to terminal 2 on the intake air heater for more than 20 seconds.
* Set the DMM to the 4V DC hertz scale.
4. Ignition OFF, install a jumper wire between Intake Air Heater Temperature Signal circuit terminal 1 and the corresponding terminal on the intake air heater.
5. Install a jumper wire between the Intake Air Heater Heart Beat Signal circuit terminal 3 and the corresponding terminal on the intake air heater.
6. Supply 12 volts to the Intake Air Heater Switch On/Off Signal circuit terminal 2 on the intake air heater.
7. Ignition ON, measure the frequency between the Intake Air Heater Digital Response Signal circuit terminal 6 at the intake air heater and ground. Verify the frequency is within 0.7-1.1 Hz
• If within the specified range, replace the K34 glow plug control module.
• If not within the specified range, replace the E24 intake air heater.
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.