ENGINE AR-PRIMARY 3723409 - Caterpillar

Key Start Switch
Illustration 1 g00291705
Key Start SwitchThe key start switch is an input of the ECM. The switch connects to connector contact J1-40. The switch tells the ECM that the operator wants to start the engine. The ECM then initiates the neutral start function. See Normal Operation, "Neutral Start Function" for more information. The signal is open during normal operation. The switch is connected to the +battery circuit when the switch is in the START position.The switch has four terminals. Terminal "S" connects to the ECM. Terminal "B" connects to battery voltage. Terminal "C" connects to the engine shutdown control. Terminal "R" connects to the main relay.Note: After the switch is initially turned to the START position, the switch will not return to the START position from the ON position. The switch must be turned to the OFF position. The switch can then be turned to the START position.The ECM does not record diagnostic codes that occur with the key start switch.