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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1998 🢒 Seville 🢒 DTC 🢒 DTC B2422 Interior Lamp Rheostat Failure

Object Number: 154520 Size: MF
Lighting Systems Components
Cell 117: Dimming Control, IP Dimmer Switch
Handling ESD Sensitive Parts Notice
Cell 68

Circuit Description

The instrument panel integration module (IPM) receives an input from the IP dimmer switch in the headlamp switch. The IPM supplies the ground for the switch through the sensor return. The resistance of the IP dimmer switch varies between 0 ohms and 40 Kohms as the switch is operated. As the resistance of the IP dimmer switch varies, the voltage input to the IPM changes. The IPM determines the level of dimming for the switch backlighting and VF displays. The IPM then sends a message via the class 2 serial data line to the dash integration module (DIM), the driver door module (DDM), the instrument cluster (IPC), the radio (IRC), and the cellular telephone docking station (PHN) indicating level of dimming for the switch backlighting and VF displays.

Conditions for Setting the DTC

The IPM will set the DTC B2422 any time it detects that the IP dimmer switch input voltage is out of range.

Specification
Normal switch input voltage: 0.095-4.75 V

Action Taken When the DTC Sets

The IPM will set the dimming level to maximum brightness.

Conditions for Clearing the DTC
    • The IPM sees that the IP dimmer switch input voltage is within the valid range.
    • Use the On-Boards clearing DTCs feature.
    • Use a scan tool.

Test Description

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

  1. Perform the Body Control Module Diagnostic System Check or Lighting Systems Diagnostic System Check before continuing with the diagnosis of this DTC.

    2.

  2. If DTC B2420 is also set, the concern is with the common reference wiring to the twilight delay switch and the IP dimmer switch.

    3.

  3. Checks for proper reference resistance of the twilight delay switch.

    4.

  4. Checks for an open in CKT 61 (YEL).

    5.

  5. Checks for a short to ground in CKT 1688 (LT BLU/BLK).

    6.

  6. Checks for an open in CKT 1688 (LT BLU/BLK).

    7.

  7. Checks if the value that the instrument panel integration module (IPM) is reading from the IP dimmer switch is too high.

    8.

  8. Checks if the value that the instrument panel integration module (IPM) is reading from the IP dimmer switch is too low.

    9.

  9. Checks for proper resistance with the IP dimmer switch set to the maximum position.

    10.

  10. Checks for an open in CKT 44 (DK GRN).

    11.

  11. Checks for proper resistance with the IP dimmer switch set to the minimum position.

    12.

  12. Checks for a short to ground in CKT 44 (DK GRN).

    13.

  13. Checks if the DTC is still set.

    14.

  14. Clear all DTCs after the repair procedure is complete.

Step

Action

Value(s)

Yes

No

1

Was the entire Body Control Module Diagnostic System Check or Lighting Systems Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - Body Control System or Diagnostic System Check - Lighting Systems

2

Is DTC B2420 for the IPM also set current?

--

Go to Step 3

Go to Step 7

3

  1. Disconnect the headlamp switch connector.
  2. Connect a DMM from the headlamp switch cavity B1 to cavity B3.

Is the resistance less than the specified value?

40K ohms

Go to Step 4

Go to Step 13

4

  1. Disconnect the instrument panel integration module (IPM) connector C2.
  2. Connect a DMM from the headlamp switch connector cavity B3 (YEL) to the IPM connector C2 cavity B8 (YEL).

Is the resistance less than the specified value?

5 ohms

Go to Step 5

Go to Step 16

5

  1. Disconnect the instrument panel integration module (IPM) connector C2.
  2. Connect a DMM from the IPM connector C2 cavity B12 (LT BLU/BLK) to ground.

Is the resistance less than the specified value?

5 ohms

Go to Step 17

Go to Step 6

6

Connect a DMM from the headlamp switch connector cavity B1 (LT BLU/BLK) to the IPM connector C2 cavity B12 (LT BLU/BLK).

Is the resistance less than the specified value?

5 ohms

Go to Step 14

Go to Step 18

7

  1. Reconnect the headlamp switch connector and the IPM connector C2.
  2. Turn the ignition switch to the ON position.
  3. Connect a scan tool to the data link connector (DLC).
  4. Select Open/Short Data from the Instrument Panel Integration Module (IPM) Data Display.
  5. Set the Interior Dim Pot units to Counts.
  6. Set the IP dimmer switch to the maximum value.

Is the Interior Dim Pot value greater than the specified value?

250 Counts (4.75 Volts)

Go to Step 9

Go to Step 8

8

Set the IP dimmer switch to the minimum value.

Is the Interior Dim Pot value less than the specified value?

5 Counts (0.095 Volts)

Go to Step 11

Go to Step 14

9

  1. Disconnect the headlamp switch connector.
  2. Connect a DMM from the headlamp switch cavity B2 to cavity B3.

Is the resistance less than the specified value?

40K ohms

Go to Step 10

Go to Step 13

10

  1. Disconnect the instrument panel integration module (IPM) connector C2.
  2. Connect a DMM from the IPM connector C2 cavity B11 (DK GRN) to the headlamp switch connector cavity B2 (DK GRN).

Is the resistance less than the specified value?

5 ohms

Go to Step 14

Go to Step 19

11

  1. Disconnect the headlamp switch connector.
  2. Connect a DMM from the headlamp switch cavity B2 to cavity B3.

Is the resistance less than the specified value?

5 ohms

Go to Step 12

Go to Step 13

12

  1. Disconnect the instrument panel integration module (IPM) connector C2.
  2. Connect a DMM from the IPM connector C2 cavity B11 (PPL) to ground.

Is the resistance less than the specified value?

5 ohms

Go to Step 20

Go to Step 14

13

Replace the headlamp switch. Refer to Headlamp Switch Replacement in Instrument Panel, Gauges and Console.

Is the headlamp switch replacement complete?

--

Go to Step 21

--

14

  1. Clear DTCs. Refer to Diagnostic Trouble Code (DTC) Clearing .
  2. Cycle the ignition switch from the OFF to ON position.
  3. Check the Instrument Panel Integration Module (IPM) for DTCs. Refer to Diagnostic Trouble Code (DTC) Displaying .

Is DTC B2422 set as current?

--

Go to Step 15

Go to Diagnostic System Check - Body Control System or Diagnostic System Check - Lighting Systems

15

Replace the instrument panel integration module (IPM). Refer to Body Control Module Replacement in Body Control System.

Is the IPM replacement complete?

--

Go to Step 21

--

16

Repair the open in CKT 61 (YEL) between the headlamp switch and S209. Refer to Wiring Repairs in Wiring Systems.

Is the circuit repair complete?

--

Go to Step 21

--

17

Repair the short to ground in CKT 1688 (LT BLU/BLK). Refer to Wiring Repairs in Wiring Systems.

Is the circuit repair complete?

--

Go to Step 21

--

18

Repair the open in CKT 1688 (LT BLU/BLK) between the IPM and the headlamp switch. Refer to Wiring Repairs in Wiring Systems.

Is the circuit repair complete?

--

Go to Step 21

--

19

Repair the open in CKT 44 (DK GRN) between the IPM and the headlamp switch. Refer to Wiring Repairs in Wiring Systems.

Is the circuit repair complete?

--

Go to Step 21

--

20

Repair the short to ground in CKT 44 (DK GRN). Refer to Wiring Repairs in Wiring Systems.

Is the circuit repair complete?

--

Go to Step 21

--

21

  1. Turn the ignition switch to the OFF position.
  2. Reconnect or install any connectors or components that were disconnected or removed.
  3. Turn the ignition switch to the ON position.
  4. Clear any DTCs. Refer to Diagnostic Trouble Code (DTC) Clearing .

Are all DTCs cleared?

--

Go to Diagnostic System Check - Body Control System or Diagnostic System Check - Lighting Systems

--