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

Diagnostic Chart:

Diode Module Circuit:

CIRCUIT DESCRIPTION
The Engine Control Module (ECM) receives an idle-up signal at terminal "C5" from the diode module. This signal is present whenever one or more of the following systems is turned On or operated.

^ Headlights.
^ Rear window defogger.
^ Heater blower motor.

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

CHART 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 for a faulty diode module.

DIAGNOSTIC AIDS
An intermittent malfunction may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connections before component replacement.