P279A Possible Causes
- Faulty Engine Control Module (ECM)
- Engine Control Module (ECM) harness is open or shorted
- Poor electrical connection in Engine Control Module (ECM) circuit
How to Fix Code P279A
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.
Possible Symptoms
Illuminated engine light (or service engine soon warning light)
P279A Meaning
The Engine Control Module (ECM) uses the following two methods to determine whether the transfer case is in 4WD Low, 4WD High, or Neutral.
1. The first method is to compare the transmission output speed sensor with the transfer case output speed sensor to calculate the transfer case range.
2. The second method is to use a LAN message sent from the transfer case shift control module to the ECM.
The ECM uses this message to determine required engine torque and transmission shifting.
Internal fault detection is handled within the control module. No external circuit diagnosis is involved.