Idle Up Control Valve: Testing and Inspection

Diagnostic Chart:

Idle-Up Signal Electrical Schematic:

CIRCUIT DESCRIPTION:
The ECM receives an idle-up signal at terminal "B3" from the diode module. This signal is present whenever one or more of the following systems is turned "ON."

^ Head lights.
^ Rear window defogger.
^ Stoplights.
^ Heater blower motor.
^ Radiator cooling fan.

The engine rpm will slightly increase for the additional electrical load.

TEST DESCRIPTION: Numbers below refer to the numbers on the diagnostic chart.

1. Checking for electrical load signal to ECM.
2. This is checking for an open circuit to the ECM or a faulty ECM or a faulty diode module.