B1440

DTC B1440

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. 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:

* Inactive
* Start active
* Off active
* Short detect

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1440 Power Mode Master Input Circuits Mismatch





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

B1440 03

The RCDLR detects a short to ground on its mode data input circuit, for more than 60 seconds.

B1440 08
* The RCDLR input does not match the state of the mode switch received from the IPM.
* The RCDLR receives a message from the IPM, indicating that a switch has been pressed, without seeing the corresponding input go active.
* The RCDLR mode data input is active for more than 60 seconds, without seeing the corresponding message from the IPM.

Action Taken When the DTC Sets

The Service Vehicle Soon (SVS) indicator will illuminate. Also, the following scenarios may take place:

* If the RCDLR senses a change on its ignition mode data input, but does not receive the corresponding message from the IPM, the RCDLR will enable the backup power mode. The backup power mode will be the old power mode. If a second change is sensed by RCDLR on its ignition mode data input, without the corresponding message from the BCM, the backup power mode will be changed accordingly to signal sensed.
* If the RCDLR receives a message from the IPM, indicating that a switch has been pressed, without sensing the change itself, the setting of the backup power moding will be disabled for the current ignition cycle.

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 setting of this DTC can be caused by various failures:

* The RCDLR malfunction
* The IPM malfunction
* The ignition mode switch malfunction
* The ignition mode data input circuits to either RCDLR or IPM

Test Description

Step 1 - Step 10:

Step 11 - Step 22:

Step 23 - Step 25:

The number below refers to the step number on the diagnostic table.
3. This step checks for a proper reading of the ignition mode switch by the RCDLR.