Starting Mode

WARNING: This page is about a different variant/trim than selected.

ECM Wake-Up Fuel Pump Prime

When specific enable criteria are met, a fuel pump prime event will occur at any ECM wake up, prior to ignition ON. Voltage is supplied to the ECM via the KR171 Engine Control Module Wake-Up Relay. When a wake up is detected, the BCM supplies a signal via CAN Bus to the ECM, closing the ground switch at the coil side of the KR171 Relay. Ignition voltage is then sent to the ECM to activate the K111 Fuel Pump Control Module. After voltage has been provided for 2 s, the relay ground switch is turned off, ending this fuel pump prime event.

Ignition On Fuel Pump Prime

If enable criteria is not met, the ECM supplies voltage to the fuel pump control module when the ECM detects that the ignition is ON. The voltage from the ECM to the fuel pump control module remains active for 2 s, unless the engine is in Crank or Run. While this voltage is being received, the fuel pump control module closes the ground switch of the fuel tank fuel pump module and also supplies a varying voltage to the fuel tank fuel pump module in order to maintain the desired fuel line pressure. The ECM calculates the air/fuel ratio based on inputs from the engine coolant temperature (ECT), manifold absolute pressure (MAP), mass air flow (MAF), and throttle position sensors. The system stays in starting mode until the engine speed reaches a predetermined RPM.

During a cold start, the ECM commands dual-pulse mode during Open Loop operation to improve cold start emissions. In dual-pulse mode, the injectors are energized twice during each injection event.

Model Year 2019 and Later

Starting mode occurs when the below conditions are present:

The vehicle has been sitting for a predetermined length of time
Engine coolant is below a specific temperature

Starting mode is only allowed once per key cycle, or up to three accessory wake up events. Below are examples of a wake up event:

Unlocking the doors using the key fob
Unlocking the doors through passive entry
Opening the truck/hatch/tailgate using the key fob
Opening the truck/hatch/tailgate through passive entry
Commanding a remote start event using the key fob
Accessory mode is enabled

Below are the conditions why Starting mode would be disabled:

The vehicle has been in a collision
Coolant temperature is out of starting mode range
DTC present in the fuel system
Hood ajar or Hood switch DTC is present
Number of Starting Mode attempts exceeded
Power mode switch, not in off or accessory mode