Chart A-1 Inoperative Service Air Conditioning Telltale

Chart A-1:

Service Air Conditioning Lamp Circuit:

DESCRIPTION:

Power is distributed to the telltale bulb from switched ignition-1 CKT 39. The BCM then grounds or ungrounds CKT 721 to operate the telltale. The BCM performs a 2 second bulb check with each cycle of the ignition switch.

NOTES ON FAULT TREE:

1. If the "SERVICE AIR CONDITIONING" lamp does not illuminate at key-on and a "c," "d," or "-151" appears on one of the displays, the BCMs microprocessor is not functioning properly which could be due to an improper PROM insertion or faulty components in the BCM.

2. If the "SERVICE AIR CONDITIONING" lamp cannot be illuminated by providing a ground to CKT 721, the problem is in the bulb circuitry.

3. If the bulb can be illuminated, then battery ignition and ground integrity must be checked to the BCM. If circuits check OK, the BCM connector or BCM is faulty.