Circuit Description
The body control module (BCM) monitors the battery voltage through the battery positive voltage circuit. If the BCM senses that battery voltage is outside of its normal range for 1 second, DTC B1420 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B1420 Device Voltage
Conditions for Running the DTC
The voltage supplied to the body control module is in the range of 7-26 volts.
Conditions for Setting the DTC
| • | The BCM senses a battery voltage above or below the specified range of 9-16 volts. |
| • | The above condition lasts for at least 1 second. |
Action Taken When the DTC sets
| • | The BCM will disable all its outputs when a high voltage condition is detected. |
| • | 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 ignition has been cycled 100 times, 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 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Is the battery voltage input parameter in the specified range? | 9.0-16.0 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? | 9.0-16.0 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 in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Battery Inspection/Test in Engine Electrical |
6 | Test the all of ground circuits of the BCM for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 7 |
7 | Inspect for poor connections at the module harness connectors. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 |
8 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems 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 2 |
