Table C-1A Electrical Load Idle-Up Signal Check

Electrical Load Idle-Up Signal Check:

Electrical Load Idle-Up Signal Check (continued):

Electrical Load Idle-Up Signal Check:

Circuit Description

The Powertrain Control Module (PCM) receives an idle-up signal 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.

Diagnostic Aids

An intermittent malfunctions, may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Check for the following items:

^ 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.

^ A short to ground on the BRN/YEL wire may cause an open TAIL fuse.


Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.


1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

2. Check for electrical load Idle up signal to the PCM.

7. This step check the separate systems.