Circuit Description

1999 GMC Forward Control 5.7 R, AutomaticSECTION Circuit Description

Ignition voltage is supplied directly to EVAP canister purge solenoid. PCM controls solenoid by grounding control circuit through an internal switch called a driver. Primary function of driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by PCM.

When PCM is commanding a component on, voltage of control circuit should be low (near zero volts). When PCM is commanding control circuit to a component off, voltage potential of circuit should be high (near battery voltage). If fault detection circuit senses a voltage other than what is expected, fault line status will change, causing DTC to set.

DTC will set when PCM detects that the commanded state of the driver and actual state of the control circuit do not match and this condition is present for a minimum of 5 seconds.

RENDER: 1.0x

NO RELATED

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