GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2007 🢒 CTS 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC B1372
Table 1: Device Power Moding

Circuit Description

Normal vehicle class 2 communication will not commence until the system power mode has been identified. The dash integration module (DIM) is the power mode master (PMM). The DIM communicates the system power mode to all the modules connected to the class 2 serial data circuit. The DIM monitors the state of the IGN 1 and Accessory voltage circuits in order to determine the present system power mode.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1372 Device Ignition 1 Circuit Low

Conditions for Running the DTC

Anytime the DIM receives an input or message.

Conditions for Setting the DTC

The DIM has detected the IGN 1 voltage circuit is low for greater than 1 minute when the Accessory voltage circuit is high and the engine run flag is true.

Action Taken When the DTC Sets
    • DTC B1372 is set in the DIM.
    • The malfunction indicator lamp (MIL) is illuminated.
    • The DIM along with other modules on the class 2 serial data circuit, will execute the power mode backup strategy.

Conditions for Clearing the MIL/DTC
    • A current DTC clears and the MIL is turned OFF when the fault is no longer present.
    • A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the fault.

Diagnostic Aids

Refer to Testing for Intermittent Conditions and Poor Connections .

Device Power Moding

Key Position

Ignition Accessory/Run

Ignition 1 Run/Crank

RUN

Active

Active

CRANK

Inactive

Active

ACCY

Active

Inactive

OFF

Inactive

Inactive

Test Description

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

  1. This step tests for a short to battery voltage on the active signal circuit.

    2.

  2. This step tests the inactive signal circuit for an open or a high resistance.

    3.

  3. If any ignition switch parameters that should be inactive in the present ignition switch position are active, 2 ignition switch signal circuits may be shorted together.

Step

Action

Yes

No

Schematic Reference: Body Control System Schematics

Connector End View Reference: Data Communication Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Install a scan tool.
  2. Turn OFF the ignition.
  3. With a scan tool, observe the Ignition 1 Run/Crank and Ignition Accessory/Run parameters in the dash integration module (DIM) input data list.

Does the Ignition 1 Run/Crank and Ignition Accessory/Run parameters display Inactive?

Go to Step 3

Go to Step 6

3
  1. Turn ON the ignition, with the engine OFF.
  2. With a scan tool, observe the Ignition 1 Run/Crank and Ignition Accessory/Run parameters.

Does the Ignition 1 Run/Crank and Ignition Accessory/Run parameters display Active?

Go to Step 4

Go to Step 7

4
  1. Turn the ignition switch to the CRANK position.
  2. With a scan tool, observe the Ignition 1 Run/Crank and Ignition Accessory/Run parameters.

Does only the Ignition 1 Run/Crank parameter display Active?

Go to Step 5

Go to Step 8

5
  1. Turn the ignition switch to the ACCY position.
  2. With a scan tool, observe the Ignition 1 Run/Crank and Ignition Accessory/Run parameters.

Does only the Ignition Accessory/Run parameter display Active?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 6

6

  1. Turn OFF the ignition.
  2. Disconnect the ignition switch.
  3. With a scan tool, observe the Ignition 1 Run/Crank and Ignition Accessory/Run parameters.

Do the Ignition 1 Run/Crank and Ignition Accessory/Run parameters display Inactive?

Go to Step 12

Go to Step 9

7

  1. Turn OFF the ignition.
  2. Disconnect the DIM.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the inactive signal circuit and a good ground.

Does the test lamp illuminate?

Go to Step 13

Go to Step 10

8

Does the Ignition 1 Run/Crank or Ignition Accessory/Run parameters also indicate Active when the parameter should be Inactive?

Go to Step 11

Go to Step 12

9

Test the active signal circuit of the ignition switch for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 16

Go to Step 13

10

Test the inactive signal circuit of the ignition switch for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 16

Go to Step 12

11

Test the active signal circuit of the ignition switch for a short to another signal circuit of the ignition switch. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 16

Go to Step 12

12

Inspect for poor connections and terminal tension at the harness connector of the ignition switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 16

Go to Step 14

13

Inspect for poor connections and terminal tension at the harness connector of the DIM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

Go to Step 16

Go to Step 15

14

Replace the ignition switch. Refer to Ignition and Start Switch Replacement .

Did you complete the replacement?

Go to Step 16

--

15

Replace the DIM. Refer to Control Module References for replacement, setup and programming.

Did you complete the replacement?

Go to Step 16

--

16
  1. Use a scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK