Initial Inspection and Diagnostic Overview

A Diagnostic System Check - Body Control System (Part 1 Of 3):

A Diagnostic System Check - Body Control System (Part 2 Of 3):

A Diagnostic System Check - Body Control System (Part 3 Of 3):

SYSTEM DESCRIPTION
The Body Control Module (BCM) diagnostic system check is an organized method for defining problems that are associated with the BCM. Start with a diagnostic system check when you have a concern. The diagnostic system check will lead to the next logical step in diagnosis.

The BCM is a reliable component and is not often the cause of a malfunction. Most system complaints are caused by the following items:
^ Faulty wiring
^ Faulty connectors
^ Faulty components

If you understand the computer system and use the tables correctly, you will reduce diagnostic time and prevent unnecessary replacement of components.

DIAGNOSTIC AIDS
The following conditions may cause an intermittent operation of the BCM with no diagnostic trouble codes (DTCs) stored:
^ Any condition that results in the interruption of power to the BCM.
^ Battery voltages that are out of the specified range. The normal battery voltage is9-16 volts.
^ Loose or damaged grounds.

It may be difficult to detect and accurately diagnose an intermittent failure in the electronic system. The BCM tests for different malfunctions under different vehicle conditions. For this reason, a thorough test drive is often necessary in order to repeat a fault condition. Faulty electrical connections or faulty wiring causes most of the intermittent conditions.

When you suspect an intermittent failure, inspect the system for the following conditions:
^ Incomplete mating of the connector halves
^ Backed out terminals
^ Incorrectly formed terminals
^ Damaged terminals
^ Wire chafing
^ Faulty connections between the terminals and the wires
^ Dirty or corroded terminals
^ Damage to the connector bodies.

Use a J 35616-A whenever a diagnostic procedure requires probing or testing a terminal. Use of the J 35616-A ensures the following:
^ No damage occurs to the terminal.
^ Sufficient contact tension.

DTC P1626 sets in the powertrain control module (PCM) when the following conditions exist:
^ The ignition switch is in the RUN position.
^ The body control module (BCM) is disconnected.

When completing BCM diagnostics and repairs, refer to Computers and Control Systems for additional information on PCM related DTCs. Computers and Control Systems

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
1. This step determines if the BCM identifies its BCM type.
2. This step determines if the vehicle has the correct BCM type installed.
3. This step inspects for DTCs that are stored in the BCM memory.
5. This step inspects for a short to ground in CKT 240.
7. This step inspects for a short to ground in CKT 1540.
9. This step inspects for a short to ground in CKT39.
11. this step inspects for a short to ground in CKT43.
12. This step inspects for an open in CKT 1550.
13. This step inspects for an open in CKT 240.
14. This step inspects for an open in CKT 1540.
15. This step inspects for an open in CKT 39.
16. This step inspects for a short to B+ in CKT 39.
17. This step inspects for an open in CKT 43.
18. This step inspects for a short to B+ in CKT 43
19. This step inspects for a short to B+ in CKT 1445.
20. This step inspects for an open in CKT 1445.