For 1990-2009 cars
Body Control Module Components
Body Control System Schematics

### Circuit Description

This is the hardware Ignition 3, CKT 341, input to the body control module (BCM) from the ignition switch.

### Conditions for Setting the DTC

All of the following conditions must be met.

• | The Ignition 3 input is not active

• | The Ignition 1 input is active for 20 seconds

### Action Taken When the DTC Sets

The BCM stores DTC B1379 in memory.

### Conditions for Clearing the DTC

• | The BCM goes to sleep. The controller reinitializes with the fault cleared.

• | All BCM history codes will clear after 100 ignition cycles (from OFF to ON) with no current codes active during the 100 ignition cycles.

• | Use the Scan Tool .

### Diagnostic Aids

• | When the diagnostics direct you to take electrical measurements at the terminal assignments of the wiring harness junction blocks, refer to Power Distribution Schematics in Wiring Systems.

• | If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while wiggling the wiring and connectors. This action may often cause the malfunction to appear.

### Test Description

The numbers listed below refer to the numbers on the diagnostic table.

1. This step determines if CKT 341 is shorted to ground.

2. This step determines if the BCM is internally shorted.

3. This step determines if the cruise control module is internally shorted.

4. This step determines if voltage is supplied from the battery to the fuse.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the BCM System Check? | -- | Go to Step 2 | Go to Body Control Module System Check
2 |

1. Install the Scan Tool .
2. Turn ON the ignition, leaving the engine OFF.
3. With the Scan Tool , observe the Ignition 3 input parameter in the BCM inputs data list.

Does the scan tool display ACTIVE?

--

Go to Diagnostic Aids

Go to Step 3

3 | Inspect the CRUISE fuse. Is the fuse open? | -- | Go to Step 4 | Go to Step 7
4 |

1. Connect a test lamp between the CRUISE fuse terminals at the right IP junction block.
2. Turn ON the ignition, leaving the engine OFF.

Does the test lamp illuminate?

--

Go to Step 5

Go to Diagnostic Aids

5 |

1. Turn OFF the ignition.
2. Disconnect the BCM connector containing the ignition 3 positive voltage circuit.
3. Turn ON the ignition, leaving the engine OFF.

Does the test lamp illuminate?

--

Go to Step 6

Go to Step 11

6 |

1. Turn OFF the ignition.
2. Disconnect the cruise control module connector containing the ignition 3 positive voltage circuit.
3. Turn ON the ignition, leaving the engine OFF.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 12

7 |

1. Remove the CRUISE fuse.
2. Turn ON the ignition, leaving the engine OFF.
3. Probe both fuse terminals for the ignition 3 positive voltage circuit at the right IP junction block with a test lamp connected to a good ground.

Does the test lamp illuminate for one of the circuits?

--

Go to Step 8

Go to Step 10

8 | Test the ignition 3 positive voltage circuit for an open. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13
9 | Repair the short to ground in the ignition 3 positive voltage circuit. Did you complete the action? | -- | Go to Step 15 | --
10 | Repair the open in the ignition feed circuit to the CRUISE fuse. Did you complete the action? | -- | Go to Step 15 | --
11 | Inspect for poor connections at the harness connector of the BCM. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13
12 | Inspect for poor connections at the harness connector of the cruise control module. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14
13 | Replace the BCM. Refer to Body Control Module Replacement in Body Control Systems. Is the repair complete? | -- | Go to Step 15 | --
14 | Replace the cruise control module. Refer to Cruise Control Module Replacement in Cruise Control. Is the repair complete? | -- | Go to Step 15 | --
15 | Use the Scan Tool in order to clear the DTCs. Is the action complete? | -- | Go to Body Control Module System Check | --