Theory Of Operation

This vehicle uses a START/STOP Button for Keyless starting and for cycling the ignition on/off.

When the operator presses the Start/Stop Button, the FOBIK is validated wirelessly by the RF Hub (Radio Frequency Hub Module). If the FOBIK is recognized as belonging to the vehicle and is inside the vehicle, the system allows the ignition state of the vehicle to be changed by the operator between the LOCK, ACCESSORY, RUN, and START ignition states.

The RF HUB will log a DTC indicating an incorrect Ignition status value is present; in this state the ignition status is unknown. This will continue until the correct signal is received by the RF Hub.

EVIC Operation 

The Keyless Go feature requires the vehicle to be equipped with an EVIC display for prompts and status information. The display messages are:

• Service Keyless System
• FOB Not Detected
• FOB Left Vehicle
• Not in Park
• Push Brake Pedal and Push Button to Start
• Push Clutch Pedal and Push Button to Start
• Vehicle not in Park Warning

BCM/RF Hub Module Interaction 

There are a few things that must take place before the starter relay can apply voltage to the starter. Below are some key points to check when diagnosing a no crank condition.

The BCM requires two signals from the RF HUB to verify the ignition is in the run or start position. The voltage on the F20 circuit is one of these signals. It can be monitored in both the RF HUB and BCM data display screens as the Ignition Run/Start under the "Sensor" value. The run or start position voltage on this circuit should be at or close to battery voltage.

Simultaneously the RF HUB busses the Ignition Run/Start status to the BCM. The BCM monitors the bussed input information as the secondary verification on the Ignition Run/Start status. The bussed messages can be monitored with the scan tool in both the RF HUB and BCM data display screens.

The F20 circuit voltage and the bussed ignition run/start status message received by the BCM must agree to enable starting. Once the vehicle is started, the loss of only one ignition signal will not cause the vehicle to cycle off as long as the other feed still indicates a "run status".

The RF HUB also requires an input from the Gated park switch (hardwired) and the OK to start CAN Bus message from the TCM (Crank Enable).

Diagnostic Aids 

The No Crank Diagnostic Test assumes all of the following to be true: 

• Communication to all configured modules in the vehicle is possible with the scan tool.
• The condition is currently present.
• The TCM, PCM, RF HUB, and BCM are at the latest calibration (part number) levels.
• There are no active DTCs.
• There are no applicable Recalls.
• There are no applicable TSBs.
• There are no PCM inhibits (i.e. RPM, Trans Range, Clutch).
• The FOBIKs complete function and operation is correct.
• All battery cables and connections are clean and tight.
• There are no open fuses.
• The battery is fully charged and can pass a load test from the GR8 tester.
• The engine rotates freely.
• Any aftermarket equipment/wiring that has been installed is operating correctly.

Starter Relay Operation 

In a no crank condition the Starter Relay can be missing power at pin 85, feed at pin 30, controlled ground at pin 86 or output at pin 87. Further explanation of how a relay operates is listed below:

• Pin 85 receives power from the BCM once the parameters for the Ignition Switch position and status, and all inhibit monitors (i.e. clutch switch, RPM, etc.) are satisfied.
• Pin 30 is a constant B+ feed.
• Pin 86 is a controlled ground by a module (i.e. PCM or BCM). Once power is sent from the BCM to the pin 85 of the relay it passes through a coil and leaves the relay through pin 86 to the control module.
• Pin 87 is an output circuit to the Starter solenoid. Once the circuit on pin 86 is grounded by the control module, the coil winding in the relay magnetically pulls the internal switch closed. When the internal switch is closed the power at pin 30 is sent to pin 87 of the relay.