For 1990-2009 cars

### 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

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

DTC Symptom | DTC Symptom Descriptor
--- | ---
03 | Voltage Below Threshold
08 | Signal Invalid

### 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

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

1. 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 Connector End View Reference: Master Electrical Component List
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Did you retrieve any of the following DTCs?

• | B1325

• | B1380

• | B1385

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

3 |

1. With the scan tool, monitor the ignition mode switch parameter under RCDLR data.
2. Press the lower and upper ignition mode switch buttons one at a time.

Does the parameter value toggle between Idle and ACC/OFF and between Idle and Run respectively?

--

Go to Step 4

Go to Step 11

4 |

1. Turn OFF the ignition.
2. Disconnect the ignition mode switch.
3. Measure the voltage between the instrument panel module (IPM) ignition mode switch reference voltage circuit at the ignition mode switch connector and a good ground.

Is the voltage measured within the specified range?

B+

Go to Step 5

Go to Step 6

5 | Measure the voltage between the IPM ignition mode switch reference voltage circuit and the IPM ignition mode signal circuit at the ignition mode switch connector. Is the voltage measured within the specified range? | B+ | Go to Step 7 | Go to Step 8
6 |

1. Disconnect the IPM.
2. Test the IPM ignition mode switch reference voltage circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 21

7 |

1. Disconnect the IPM.
2. Test the IPM ignition mode data signal circuit of the IPM for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 9

8 |

1. Disconnect the IPM.
2. Test the IPM ignition mode data signal circuit for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 21

9 | While measuring the resistance between the IPM ignition mode data signal and IPM ignition mode switch reference voltage circuits at the ignition mode switch, press the OFF/ACC button of the ignition mode switch. Is the value measured approximately as specified? | 270 Ω | Go to Step 10 | Go to Step 23
10 | While measuring the resistance between the IPM ignition mode data signal and IPM ignition mode switch reference voltage circuits at the ignition mode switch, press the START button of the ignition mode switch. Is the value measured approximately as specified? | 450 Ω | Go to Step 21 | Go to Step 23
11 |

1. Turn OFF the ignition.
2. Disconnect the ignition mode switch.
3. Measure the voltage between the remote control door lock receiver (RCDLR) ignition mode data signal circuit at the ignition mode switch connector and a good ground.

Is the voltage measured within the specified range?

B+

Go to Step 12

Go to Step 14

12 | 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 15 | Go to Step 13
13 | 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 17 | Go to Step 16
14 |

1. Disconnect the RCDLR.
2. Test the ignition mode data signal circuit of the RCDLR for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 19

15 |

1. Disconnect the RCDLR.
2. Test the ignition mode data signal circuit of the RCDLR for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 19

16 |

1. Disconnect the RCDLR.
2. Test the ignition mode ground circuit of the RCDLR for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 19

17 | While measuring the resistance between the RCDLR ignition mode data signal and RCDLR ignition mode ground circuits at the ignition mode switch press the ACC/OFF button of the ignition mode switch. Is the value measured approximately as specified? | 2,000 Ω | Go to Step 18 | Go to Step 23
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 START button of the ignition mode switch. Is the value measured approximately as specified? | 0 Ω | Go to Step 19 | Go to Step 23
19 | Inspect for poor connections and terminal tension at the harness connector of the RCDLR module. Refer to Testing for Intermittent Conditions and Poor Connections . Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 20
20 | Replace the RCDLR module. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 25 | --
21 | Inspect for poor connections and terminal tension at the harness connector of the IPM. Refer to Testing for Intermittent Conditions and Poor Connections . Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 22
22 | Replace the IPM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 25 | --
23 | 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 . Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 24
24 | Replace the ignition mode switch. Refer to Ignition and Start Switch Replacement . Did you complete the replacement? | -- | Go to Step 25 | --
25 |

1. Reconnect all components.
2. Use the scan tool in order to clear the DTC.
3. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 3

System OK