• | 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 provide an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage |
---|---|---|---|
IAH Temperature Signal | -- | P154D | P154D |
IAH Command 2 | P154B | P154B | P154B |
IAH Voltage Signal | P154B | P154B | P154B |
IAH Command 1 | P154B | P154B | P0640 |
IAH Current Signal | P154C | P154C | P154C |
IAH Feedback Signal | P154A | P154A | P154A |
IAH Battery Positive Voltage | -- | P154B | -- |
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 |
• | 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. |
The GPCM detected an open, short to ground or short to battery on the IAH current signal circuit.
DTC P154C is a Type B DTC.
DTC P154C is a Type B DTC.
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Observe the following with a scan tool.
Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
Important: Set the DMM to the 4V DC hertz scale.
⇒ | 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.
⇒ | 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. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for GPCM replacement, setup, and programming |