Circuit Description

WARNING: This page is about a different car, the 2000 Pontiac Firebird, 2000 Chevrolet Corvette, and 2000 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.

Voltage is supplied directly to 1-4 upshift light. PCM controls shift light signal by grounding this 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.

Conditions for setting DTC are: engine speed is greater than 400 RPM, ignition voltage is greater than 6 volts but less than 18 volts, PCM detects commanded state of driver and actual state do not match and conditions are met for 5 seconds.