Circuit Description
The body control module (BCM) monitors the system voltage through the battery voltage signal circuit. Damage to components, and incorrect data can occur when the voltage is out of range. Refer to Body Control System Schematics .
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B1325 Device Power 1 Circuit Voltage Below/Above Threshold
Conditions for Running the DTC
The voltage supplied to the BCM is in the range of 7-26 volts.
Conditions for Setting the DTC
DTC B1325 Type 03
| • | The BCM detects a system voltage below 9 volts. |
| • | The above condition is present at least 5 seconds. |
DTC B1325 Type 07
| • | The BCM detects a system voltage above 18 volts. |
| • | The above condition is present at least 5 seconds. |
Action Taken When the DTC Sets
| • | The BCM immediately disables all outputs when a high voltage condition was detected, with the exception of GMLAN and Run/Crank relay that are disabled after a 3 minutes delay. |
| • | The setting of other DTCs is inhibited. |
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 Signal parameter displayed in the specified range? | 9-18 V | Go to Step 3 | Go to Step 4 |
3 | Is the DTC set as a current DTC? | -- | Go to Step 7 | Go to Diagnostic Aids |
4 |
Is the measured value in the specified range? | 9-18 V | Go to Step 6 | Go to Step 5 |
5 | Test the Battery Voltage Signal 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 Charging System Test |
6 | Test the all of 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 module 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 2 |
