Engine Starting System - 2001 Chevy Venture

There was a post in the automotive forums recently asking about the Engine Starting System operation. 
Here is some information I gathered from a couple of repair manuals that might help in troubleshooting and repairing
any problems that you might have in this area.

Engine Starting System - Description & Operation

The starting system includes the following major components:

  • Starter & Battery
  • Starter Relay (see relays)
  • Two (2) fuses (10 Amp fuse #11 [PCM, Ignition Crank] & #50 [Ignition Main Relay & PCM])
  • Ignition Switch and Park/Neutral Position Switch
  • Power train Control Module (PCM)
  • All associated wiring & connectors, including a "Fusible link"

Basic Operation: 

  • When the Ignition Switch is turned to START, 12 Volts is sent through fuse #11 to the PCM (pin 23).
  • If the transmission is in the Park or Neutral position, 12 Volts is present at pin 85 of the Starter Relay, and the PCM provides a Ground to pin 86 of the relay.
  • When the Starter Relay closes, it feeds current from the battery, through the starter solenoid, and to the starter motor.
  • When the Ignition Switch is release, the starter relay opens and the starter solenoid de-energizes.

Other information:

  • A fusible link protects starter relay and solenoid from excess current.

Here is the schematic for the engine starting system.  Click on it for a larger view.
Engine Starting System Schematic

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