Circuit Description
The body control module (BCM) monitors the OFF/RUN/CRANK signal from the ignition switch. The signal is zero when there is no key in the ignition cylinder. The signal is at the 12-volt reference level when a key is placed into the ignition cylinder. When the vehicle operator places the ignition switch in the Run position, the switch supplies +5 volts to the BCM OFF/RUN/CRANK input terminal. During a crank event, the +5 volt signal is passed through an internal resistor in the ignition switch for discrimination of the crank command. If the OFF/RUN/CRANK circuit becomes shorted to B+, ground or the circuit opens, DTC B1441 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B1441 Device Ignition OFF, RUN and CRANK Circuit
This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description .
DTC Symptom | DTC Symptom Descriptor |
|---|---|
01 | Short to Battery |
02 | Short to Ground |
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 BCM detects a short to ground in the OFF/RUN/CRANK voltage circuit when the ignition switch is in RUN or CRANK. |
| • | The BCM detects a short to battery or an open in the OFF/RUN/CRANK circuit. |
| • | Any of the conditions above must be present for more than 10 seconds. |
Action Taken When the DTC Sets
| • | The BCM stores DTC to memory. |
| • | The BCM operates in a fail-safe power mode dependent on the last valid power mode detected and the state of the engine run flag data on the GMLAN serial data communications circuits. |
| • | The other modules on the vehicle operate in a fail-safe power mode dependent on the last valid power mode transmitted by the BCM and the state of the engine run flag on the GMLAN serial data communications circuits. |
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
A history DTC may be caused by an intermittent short or open in the OFF/RUN/CRANK circuit or the +5-volt reference circuit. Refer to Testing for Intermittent Conditions and Poor Connections .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This tests the OFF/RUN/CRANK circuit for a short circuit to B+ and ground. Because of the control over powermoding this step must be performed with the switch in the OFF position. Any shorts to ground during this step could be a short to a voltage circuit that is only powered in Run or Accessory. The loads on these circuits would indicate a short to ground, but the cause would have to be traced thorough the OFF/RUN/CRANK circuit and repaired.
-
This tests the ignition switch contacts of the OFF/RUN/CRANK circuit for merit.
-
This tests the OFF/RUN/CRANK, +5-volt and +12-volt circuits for an open.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Body Control System Schematics and Power Distribution Schematics Connector End View Reference: Master Electrical Component List | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Does the scan tool display DTC B1441 as current? | -- | Go to Step 3 | Go to Diagnostic Aids |
Did you find and correct the condition? | B+ | Go to Step 9 | Go to Step 4 | |
|
Important: The engine may crank during this procedure.
Can you measure continuity and is the resistance within value in the CRANK position? | -- | Go to Step 7 | Go to Step 5 | |
Test the OFF/RUN/CRANK, +12-volt reference and +5-volt reference circuits of the ignition switch harness connector and the BCM harness connector for an open condition. Test the terminals at ignition switch harness connector for the proper tension Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 6 | |
6 | Replace the ignition switch. Refer to Ignition and Start Switch Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- |
7 | Test the OFF/RUN/CRANK, +12-volt reference and +5-volt reference terminals of the BCM harness connector for the proper terminal tension and intermittent and poor connections. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 | |
8 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 9 | -- |
9 |
Does the DTC reset? | -- | Go to Step 1 | System OK |
