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.
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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 | |||||
Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 6 | |||||
6 | Replace the ignition switch. 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 | ||||
