Circuit Description

WARNING: This page is about a different car, the 2002 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

Ignition 1 voltage is supplied from the fuse block to the instrument cluster (IPC) by the ignition 1 voltage circuit. The powertrain control module (PCM) controls the hot coolant indicator by grounding the hot coolant indicator control circuit via the underhood accessory wiring junction block. The PCM has an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component ON, the voltage potential of the control circuit should be low (near 0 volts). When the PCM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high (near battery voltage). If the fault detection circuit senses a voltage other than what is expected, the DTC will set. The PCM will monitor the control circuit for the following:

A short to ground
A short to voltage
An open circuit