Chart C-1A Electric Load Idle-Up Signal Check

Chart C-1A:

Electrical Load Circuit:

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.
^ Brake lights.
^ 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.