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Testing the main B+ cable to the starter would be my first step , after checking for DTC'S -diagnostic trouble codes . Voltage drop test the circuit > The fact that it clicks is a good indication the control side of the starter circuit is good . Or least wise you should hope that's the problem ,you have know idea how complex the control side of the starter is . The control side is computer controlled , the ignition switch is a low voltage input to the BCM - body control module . The BCM sends a Meassage on the GMLAN serial data network to the PCM - engine computer that crank is requested . The PCM will then energize the crank relay if it see's an input from the transmission that the vehicle is in park or neutral an no problems with the anti-theft system .
Factory service manual discription for starting system
When the ignition switch is placed in the Start position a discrete signal is supplied to the body control module (BCM) notifying it that the ignition is in the Start position. The BCM then sends a message to the engine control module (ECM) notifying it that CRANK has been requested. The ECM verifies that the transmission is in Park or Neutral. If it is, the ECM then supplies 12 volts to the control circuit of the starter relay. When this occurs battery positive voltage is supplied through the switch side of the starter relay to the starter solenoid.
For ignition switch power modes refer to Body Control System Description and Operation . When the ignition switch is placed in the Start position a discrete signal is supplied to the body control module (BCM) notifying it that the ignition is in the Start position. The BCM then sends a message to the engine control module (ECM) notifying it that CRANK has been requested. At the same time the BCM is supplying 12 volts for the IGN 1 relay closing it and supplying battery positive voltage for the crank relay coil. The ECM verifies that the transmission is in Park or Neutral. If it is, the ECM grounds the control circuit of the crank relay. When this occurs battery positive voltage is supplied through the switch side of the crank relay to the S terminal of the starter solenoid.
Sorry but your best bet would be to take it to a qualified repair shop ! Or the Chevy dealer . Could have DTC'S - diagnostic trouble codes stored in the BCM !
DTC P0615 Starter Relay Control Circuit
Ignition ON, verify that no starter relay, theft deterrent, or automatic transmission DTCs are set that would cause the ECM to disable starting.
? If DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
Ignition ON, observe the scan tool BCM Starter Switch parameter. Place ignition switch in the crank position, the parameter should display ON.
? If not the specified value, refer to Power Mode Mismatch .
Transmission range selector in park , verify the scan tool ECM PNP Switch and TCM IMS parameters display Park/Neutral.
? If the TCM IMS parameter does not indicate Park/Neutral, refer to Transmission Internal Mode Switch Logic .
? If the ECM Park/Neutral parameter does not indicate Park/Neutral, refer to ECM Park Switch Circuit Malfunction.
Transmission range selector in park or neutral, attempt to start the vehicle. The starter relay should click and the engine should begin cranking.
? If the starter relay does not click or the engine does not crank, refer to Starter Relay Circuit Malfunction.
Power to many of this vehicle's circuits are controlled by the module that is designated the Power Mode Master (PMM). This vehicle's PMM is the Body Control Module (BCM). The PMM controls which power mode (Run, Accessory, Crank, Retained Accessory Power, or Off) is active.
Serial Data Power Mode
On vehicles that have several control modules connected by serial data circuits, one module is the power mode master (PMM). On this vehicle, the PMM is the body control module (BCM). The PMM receives 3 discrete ignition switch signals to differentiate which power mode will be sent over the Serial Data circuits. The table below illustrates the state of these inputs in correspondence to the ignition switch position:
Safety switch ? For what ? Park neutral safety switch ,is this what you mean ? Your vehicle not starting ? There is a lot more involved then just that switch.
For ignition switch power modes refer to Body Control System Description and Operation. Once the ignition is placed in the Run/Crank position, the control circuit of the Run/Crank relay is grounded by the body control module (BCM). With the Run/Crank relay switch closed, battery positive voltage flows through it and on to the park/neutral position (PNP) switch. With the PNP switch in either the Park or Neutral position, battery positive voltage will flow to the starter relay coil supply voltage input terminal of the powertrain control module and the coil side of the starter relay. Placing the ignition in the START position sends a message to the engine control module (ECM)/powertrain control module (PCM) requesting engine start. If the ECM/PCM has determined that the transmission is in Park or Neutral and theft is not active, it will ground the control circuit of the starter relay. Battery positive voltage will then flow through the switch side of the starter relay to the S terminal of the starter solenoid, cranking the engine. For remote vehicle start (RVS) information, refer to Keyless Entry System Description and Operation.
CHECK ALTERNATOR POWER FEED WIRE AND VOLTAGE REGULATOR WIRES FOR EXPOSED WIRES SHORTING TO GROUND.CHECK BATTERY POSITIVE CABLE FROM ALTERNATOR TO STARTER. LOOK FOR SIGNS BURNT WIRES.YOU HAVE POSITIVE BATTERY CABLE SHORTING TO GROUND.OR STARTER SOLENOID OR STARTER SHORTING OUT.TRANSMISSION NEUTRAL SWITCH OR IGNITION SWITCH WIRES SHORTING OUT IGNITION.
sounds like a loose wire at the battery,check both termanals and dont be afraid to give them a good shake also get the wires from the battery to the starter checked even the small ign wire to the starter.adrian,,,,,,