Engine Controls - Tests W/Codes - Pcm/BCM: Description

Reatta and Riviera models use several electronic components which can be controlled by the service technician to provide valuable self-diagnostic information. The components are part of an electrical network designed to control various engine and body subsystems. This article will provide a description of the overall electronic network and the on-board diagnostic capabilities which have been designed to aid the service technician in system diagnosing and testing.

At the heart of the computer system is the Body Control Module (BCM). The BCM is located behind the glove box and has an integral microprocessor, which is the center for communication with all other components in the system. All sensors and switches are monitored by the BCM or by one of the following major components:

Electronic Heater and A/C Control Panel (ECCP)
Instrument Panel Cluster (IPC)
Programmer-Heating and A/C (HVAC)
SIR Diagnostic Energy Reserve Module (DERM) controller
Electronic Control Module (ECM)

NOTE: The Electronic Control Module (ECM) may be referred to as the Powertrain Control Module (PCM) in some diagnostic charts and figures. The 2 terms may be used interchangeably.

Fig 1: Instrument Panel Cluster (Analog) & Electronic Climate Control Panel (ECCP)

Courtesy of GENERAL MOTORS CORP.

Vehicle utilizes an Electronic Climate Control Panel (ECCP) with LED digital display area for climate control/temperatures and override mode values. ECCP is used to access BCM diagnostics and display them in the IPC Driver Information Center (DIC) located in odometer/trip odometer display.