Circuit Description
The body control module (BCM) 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 |
If the BCM detects a change in the ignition mode switch data, sends a class 2 message to RCDLR requiring authentication for that change.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B1440 Power Mode Master Input Circuits Mismatch
Conditions for Running the DTC
The only requirements are voltage and ground.
Conditions for Setting the DTC
The RCDLR sets this code if any of the following conditions occur:
| • | The RCDLR mode data input is active for more than 60 seconds, without seeing the corresponding message from the BCM. |
| • | The RCDLR detects a short to ground on its mode data input circuit, for more than 60 seconds. |
Action Taken When the DTC Sets
One of the following scenarios may take place:
| • | If the RCDLR senses a change on its ignition mode data input two times in a row, but does not receive the corresponding message from the BCM, the RCDLR will enable the backup power mode. The backup power mode will be changed accordingly to signal sensed. |
| • | If the RCDLR receives a message from the BCM, indicating that a switch has been pressed, without sensing the change itself, 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 BCM malfunction |
| • | The ignition mode switch malfunction |
| • | The ignition mode data input and ground circuits for either the RCDLR or the BCM |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step checks for a proper reading of the ignition mode switch by the BCM.
-
This step checks for a proper reading of the ignition mode switch by the RCDLR.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Power Distribution Schematics in Wiring Systems Connector End View Reference: Master Electrical Component List in Wiring Systems | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
|
Important: The engine may start during this procedure. Turn OFF the engine after verifying this power mode.
Does the current power mode data follow the ignition mode switch positions? | -- | Go to Step 11 | Go to Step 3 | |
3 |
Is the voltage measured within the specified range? | B+ | Go to Step 4 | Go to Step 6 |
4 | Install a test lamp between the BCM ignition mode data signal circuit at the ignition mode switch connector and a good ground. Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 5 |
5 | Measure the voltage between the BCM ignition mode data signal circuit and the BCM ignition mode ground circuit at the ignition mode switch connector. Is the voltage measured within the specified range? | B+ | Go to Step 9 | Go to Step 8 |
6 |
Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 22 |
7 |
Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 22 |
8 |
Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 22 |
9 | While measuring the resistance between the BCM ignition mode data signal and BCM ignition mode ground circuits at the ignition mode switch press the OFF/ACC button of the ignition mode switch. Is the value measured approximately as specified? | 300 ohms | Go to Step 10 | Go to Step 24 |
10 | While measuring the resistance between the BCM ignition mode data signal and BCM ignition mode ground circuits at the ignition mode switch press the START button of the ignition mode switch. Is the value measured approximately as specified? | 1500 ohms | Go to Step 22 | Go to Step 24 |
|
Important: The engine may start during this procedure. Turn OFF the ignition after verifying this power mode.
Does the ignition mode switch data follows the ignition mode switch positions? | -- | Go to Step 20 | Go to Step 12 | |
12 |
Is the voltage measured within the specified range? | B+ | Go to Step 13 | Go to Step 15 |
13 | Install a test lamp between the RCDLR ignition mode data signal circuit at the ignition mode switch connector and a good ground. Does the test lamp illuminate? | -- | Go to Step 16 | Go to Step 14 |
14 | Measure the voltage between the RCDLR ignition mode data signal circuit and the RCDLR ignition mode ground circuit at the ignition mode switch connector. Is the voltage measured within the specified range? | B+ | Go to Step 18 | Go to Step 17 |
15 |
Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 20 |
16 |
Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 20 |
17 |
Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 20 |
18 | While measuring the resistance between the RCDLR ignition mode data signal and RCDLR ignition mode ground circuits at the ignition mode switch press the OFF/ACC button of the ignition mode switch. Is the value measured approximately as specified? | 2000 ohms | Go to Step 19 | Go to Step 24 |
19 | While measuring the resistance between the RCDLR ignition mode data signal and RCDLR ignition mode ground circuits at the ignition mode switch press the START button of the ignition mode switch. Is the value measured approximately as specified? | 0 ohms | Go to Step 20 | Go to Step 24 |
20 | Inspect for poor connections and terminal tension at the harness connector of the RCDLR module. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 21 |
21 | Replace the RCDLR module. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 26 | -- |
22 | Inspect for poor connections and terminal tension at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 23 |
23 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 26 | -- |
24 | Inspect 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 26 | Go to Step 25 |
25 | Replace the ignition mode switch. Refer to Ignition and Start Switch Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement? | -- | Go to Step 26 | -- |
26 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
