Circuit Description
The DIM has a designated circuit for monitoring vehicle system voltage. Also, other modules monitor system voltage. The DIM sends a system voltage message to other modules that do not monitor system voltage via Class 2 message. When the DIM sets B1390, the system voltage message sent to the other modules will default to 12.9 volts.
Conditions for Running the DTC
This DTC shall run only if the DIM has power, ground and the ignition is not in START mode. This DTC shall execute regardless of the battery voltage, except when the DTC B1390 is set current.
Conditions for Setting the DTC
| • | This DTC shall be set as current when the voltage falls below 9.0 volts for 1.2 seconds. |
| • | When the vehicle exits START the DIM shall delay checking the voltage for 2 seconds. |
Action Taken When the DTC Sets
| • | A message shall be sent out on the class 2 lines to notify all other modules of low battery voltage. |
| • | The modules disable the setting of U codes and other DTCs. |
Conditions for Clearing the DTC
| • | The DTC will clear current status when the voltage is less than 15.5 volts for 1.2 seconds. |
| • | A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present. |
| • | Use the ON-Board clearing DTCs feature. |
| • | Use a scan tool. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Tests for the proper voltage at battery positive voltage sense circuit of the DIM, if voltage is not within the proper operating range, the voltage sense circuit needs to be tested.
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Tests the ground sense circuit of the DIM.
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Tests for the proper voltage at any other module setting the DTC B1327. If voltage is not within the proper operating range, the battery positive voltage and ground circuits of the module needs to be tested.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Starting and Charging Schematics or Power Distribution Schematics in Wiring Systems | ||||
1 | Did you perform the Engine Electrical Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Does the voltage measure greater than the specified value? | 9.4 Volts | Go to Step 5 | Go to Step 3 |
Does the voltage measure greater than the specified value? | 9.4 Volts | Go to Step 9 | Go to Step 4 | |
Measure the voltage from the battery positive voltage circuit at terminal A12,C1 of the DIM to a good ground. Does the voltage measure greater than the specified value? | 9.4 Volts | Go to Step 8 | Go to Step 7 | |
Does the voltage measure greater than the specified value? | 9.4 Volts | Go to Step 9 | Go to Step 6 | |
6 | Measure the voltage between the battery positive voltage circuit of the module setting the DTC B1327 and a good ground. Does the voltage measure greater than the specified value? | 9.4 Volts | Go to Step 8 | Go to Step 7 |
7 | Test the batter positive voltage circuit of the module setting the code for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 9 |
8 | Test the ground sense circuit of the module setting the code for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 9 |
9 | Inspect for poor connections at the harness connector of the module setting the code. 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 11 | Go to Step 10 |
10 |
Important: Perform the setup procedure for the module setting the code, if necessary. Replace the module setting the code. Refer to Control Module References in Body Control System. Did you complete the replacement? | -- | Go to Step 11 | -- |
11 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
