Circuit Description
The body control module (BCM) monitors the battery voltage through the battery positive voltage circuit from the TBC fuse.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B1420 Device Voltage
Conditions for Running the DTC
The voltage supplied to the BCM is in the range of 7-26 volts.
Conditions for Setting the DTC
| • | The BCM senses a battery voltage above 16.7 volts. |
| • | The above condition lasts for at least 1 second. |
Action Taken When the DTC sets
| • | The BCM will disable all its outputs. |
| • | The setting of this DTC inhibits the setting of other DTCs. |
Conditions for Clearing the DTC
| • | A current DTC clears when the malfunction is no longer present. |
| • | A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction. |
Diagnostic Aids
| • | The following may cause an intermittent: |
| - | A damaged terminal |
| - | A backed out terminal |
| - | A poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| • | When diagnosing an intermittent short or an open, manipulate the wire harness while watching the test equipment for changes. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Body Control System Schematics Connector End View Reference: Computer/Integrating Systems Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Is the battery voltage input parameter in the specified range? | 9.0-16.7 V | Go to Step 3 | Go to Step 4 |
3 | Is DTC B1420 set as a current DTC? | -- | Go to Step 7 | Go to Diagnostic Aids |
4 |
Is the measured value in the specified range? | 9.0-16.7 V | Go to Step 6 | Go to Step 5 |
5 | Test the battery positive voltage circuit for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 9 | Go to Battery Inspection/Test |
6 | Test all of the ground circuits of the BCM for an open or high resistance. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 7 |
7 | Inspect for poor connections at the BCM harness connectors. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 |
8 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 9 | -- |
9 | Operate the system in order to verify the repair. Did you find and correct the condition? | -- | System OK | Go to Step 1 |
