Powertrain Control Software

Powertrain Control Software

Communications
The vehicle has 2 module communication networks: one high speed and one medium speed controller are network (CAN), which are comprised of unshielded twisted pair cable. Both networks are connected to the data link connector (DLC). For additional information, see COMMUNICATIONS NETWORK.

Engine RPM/Vehicle Speed Limiter
The PCM disables some or all of the fuel injectors whenever an engine RPM or vehicle over speed condition is detected. The purpose of the engine RPM or vehicle speed limiter is to prevent damage to the powertrain. The vehicle exhibits a rough running engine condition, and the PCM stores one of the following continuous memory DTCs: P0219, P0297, or P1270. Once the driver reduces the excessive speed, the engine returns to the normal operating mode. No repair is required. However, the technician should clear the DTCs and inform the customer of the reason for the DTC.

Excessive wheel slippage may be caused by sand, gravel, rain, mud, snow, ice, etc. or excessive and sudden increase in rpm while in NEUTRAL or while driving.

Fail-Safe Cooling Strategy
The fail-safe cooling strategy is activated by the PCM only in the event that an overheating condition has been identified. This strategy provides engine temperature control when the cylinder head temperature exceeds certain limits. The cylinder head temperature is measured by the cylinder head temperature (CHT) sensor.

A cooling system failure such as low coolant or coolant loss could cause an overheating condition. As a result, damage to major engine components may occur. Along with a CHT sensor, the fail-safe cooling strategy is used to prevent damage by allowing air-cooling of the engine. This strategy allows the vehicle to be driven safely for a short period of time when an overheat condition exists.

The engine temperature is controlled by varying and alternating the number of disabled fuel injectors. This allows all cylinders to cool. When the fuel injectors are disabled, their respective cylinders work as air pumps, and this air is used to cool the cylinders.

Failure Mode Effects Management
Failure mode effects management (FMEM) is an alternate system strategy in the PCM designed to maintain engine operation if one or more sensor inputs fail.

When a sensor input is determined to be out-of-limits by the PCM, an alternative strategy is initiated. The PCM substitutes a fixed value for the incorrect input and continues to monitor the suspect sensor input. If the suspect sensor begins to operate within limits, the PCM returns to the normal engine operational strategy.

All FMEM sensors display a sequence error message on the scan tool. The message may or may not be followed by key on engine off (KOEO) or continuous memory DTCs when attempting key on engine running (KOER) self-test mode.