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B1385 59 (2) Cadillac STS I

The IPM does not react to switch inputs of equal or lower priority until condition is cleared.

Conditions for Clearing the DTC

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Diagnostic Aids

The following can cause the code to set as history

  1. An intermittent short to battery on ignition mode switch signal circuit.
  2. An intermittent problem of the ignition mode switch
  3. The START button of the ignition mode switch was pressed for more than 30 seconds.
StepActionValuesYesNo
Schematic Reference: Power Distribution Schematics in Wiring Systems Connector End View Reference: Master Electrical Component List in Wiring Systems
1Did you perform the Diagnostic System Check - Vehicle?Go to Step 2Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2Is the DTC B1385 set as current?Go to Step 3Go to Diagnostic Aids
3Turn OFF the ignition. Disconnect the ignition mode switch. With a DMM measure the resistance between cavities E and F at the ignition mode switch. Press and release the START button during the measurement. Do the values measured toggle from one to the other specified values?0/450 ohmsGo to Step 6Go to Step 4
4Inspect for poor connections and terminal tension at the harness connector of the ignition mode switch. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition?Go to Step 9Go to Step 5
5Replace the ignition mode switch. Refer to Ignition Switch Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement?Go to Step 9
6Disconnect the instrument panel module (IPM). Test the IPM ignition mode data signal circuit for a short to battery. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 9Go to Step 7
7Inspect for poor connections and terminal tension at the harness connector of the IPM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition?Go to Step 9Go to Step 8
8Replace the IPM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?Go to Step 9
9Reconnect all components. Use the scan tool in order to clear the DTC. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset?Go to Step 3System OK

DTC B1385

Circuit Description

The instrument panel module (IPM) is the power mode master and the remote control door lock receiver (RCDLR) is the backup power mode master. The both modules receive the same information from ignition mode switch therefore are able to correctly discern all power modes. There is no degradation in vehicle operation when the backup power mode is active.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC B1422 Device Power Moding Error

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC SymptomDTC Symptom Descriptor
52Device Power Moding Compare Failure

DTC B1422

Conditions for Running the DTC

Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.

Conditions for Setting the DTC

The following conditions enable the backup power mode

  1. The RCDLR detects a loss of the power mode message from the IPM.
  2. The IPM invalidates the power mode message.
  3. The RCDLR senses a change on its ignition mode switch inputs, twice, without receiving the corresponding message from the IPM.

Action Taken When the DTC Sets

The backup power mode becomes the system power mode. This code will set following the setting of the DTC B1440.

The Service Vehicle Soon (SVS) indicator will illuminate.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

The setting of this DTC can be caused by various failures

  1. The ignition mode switch malfunction
  2. The ignition mode data input circuits to IPM
  3. The IPM malfunction

Test Description

The number below refers to the step number on the diagnostic table.

  1. 2: The setting of any of those DTCs may be followed by the setting of B1422.
StepActionValuesYesNo
Schematic Reference: Power Distribution Schematics in Wiring Systems Connector End View Reference: Master Electrical Component List in Wiring Systems
1Did you perform the Diagnostic System Check - Vehicle?Go to Step 2Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2Did you retrieve any of the following DTCs? B1380 B1385 B1440Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC InformationGo to Step 3
3Turn OFF the ignition. Disconnect the instrument panel module (IPM). Inspect for poor connections and terminal tension at the harness connector of the IPM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition?Go to Step 5Go to Step 4
4Replace the IPM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?Go to Step 5
5Use the scan tool in order to clear the DTC. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset?Go to Step 1System OK

DTC B1422

The instrument panel module (IPM) is the power mode master and the remote control door lock receiver (RCDLR) is the backup power mode master. Both modules receive information regarding ignition mode switch position from the ignition mode switch. The ignition mode switch will be monitored only with battery voltage at or above 7 volts to prevent invalid input readings during low voltages encountered during vehicle cranking.

Four modes are discernible

  1. Inactive
  2. Start active
  3. Off active
  4. Short detect

This diagnostic procedure supports the following DTC

DTC B1440 Power Mode Master Input Circuits Mismatch

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC SymptomDTC Symptom Descriptor
03Voltage Below Threshold
08Signal Invalid

DTC B1440

Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.