Auto Service Professional

DEC 2018

Magazine for the auto service professional

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30 A S P D e c e m b e r 2 018 P u s h B u t t o n S t a r t running). e vehicle will stay powered up for 3 hours and the green LED (run/start) will illumi- nate (see Figure 6). Aer being in run/start mode (ignition on without the engine running) for 1.5 hours, the vehicle will look to see if the transmitter is still present (see Figure 7). If the transmitter is not present in the vehicle, it will power down instead of staying powered up for the full 3 hours. With the ignition off (brake pedal not ap- plied), then pressing and holding the push but- ton start switch for at least 10 seconds, this will place the vehicle into Vehicle in Service Mode (ignition on without the engine running) and the green LED (run/start) will illuminate. Vehicle in Service Mode is used for service and diagnostics not requiring the operation of the gas engine. e vehicle will stay in Vehicle in Service Mode until the vehicle is manually turned off. Both LEDs have the voltage supplied from the body control module (BCM). e ignition mode switch sends the ignition mode switch status to the passive entry passive start module (peps) and to the BCM. e peps module sends a redundant signal to the BCM with the ignition mode switch status. If for any reason the transmitter is le in- side the vehicle while the vehicle is off and the driver's door has been opened and shut the ve- hicle will emit a warning sound to alert the driver that the transmitter was le inside the vehicle. Another warning system is if the vehicle is running and the transmitter is removed from the vehicle, a warning will be displayed on the instrument cluster alerting the driver that the transmitter is not in range. Diagnosing this system isn't too hard if you understand it. e ignition mode switch contains two individual switches that provide redundant switch inputs to both the body control module and the keyless entry control module. e body control module supplies the igni- tion mode switch a constant battery plus signal. e body control module monitors this signal to determine if the switch is released or pressed. When the ignition mode switch is not pressed, voltage on the signal circuit is pulled down through two resistors in the switch. When the ignition mode switch is pressed, voltage on the signal circuit is pulled down through only one resistor, changing the voltage seen at the body control module and indicating that the ignition mode switch is pressed. e keyless entry control module monitors voltage on the switch in the same manner as the body control module, but monitors the other in- dividual switch in the ignition mode switch. If for some reason the keyless entry module doesn't see the correct switch inputs or voltage require- ments then a no-start condition will exist. Figure 3: The 2019 Chevy Traverse is equipped with the start-stop system. Figure 4: When the vehicle is in the off mode, both LEDs will be off.

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