B Charts

Chart B-1:

Coolant Temperature Lamp Circuit:

DESCRIPTION:

The Coolant Temp telltale bulb is powered by ignition CKT 39 through the gauges fuse. The BCM supplies a ground to CKT 35 (BCM terminal A6) to illuminate the Coolant Temp telltale when it is determined that an overheat condition exists (coolant temp greater than 125°C (257°F). Coolant temp data is sent by the PCM to the BCM via CKT 526, PCM-BCM serial data.

NOTES ON FAULT TREE:

1. Verifies the integrity of CKTs 35 and 39, the IPC, and the Coolant Temp telltale bulb. If the bulb is ON with CKT 35 jumpered to ground at the BCM, the bulb, IPC, and associated wiring are OK, and the problem is a faulty BCM connection or BCM.

2. Checks CKT 39 to ensure that an ignition feed is being supplied to the indicators.

3. Determines whether the problem is an open CKT 35 or the IPC bulb, or connector.

4. Checks for a grounded CKT 35 or a faulty IPC.

5. Ensures that the BCM is not receiving data indicating an overheat condition from the PCM. If BCM data P.2.1 displays a coolant temperature of over 125°C (257°F), problem is either the coolant sensor circuit or the engine cooling system.