Vehicle Will Not Change Power Mode

Wiring Systems and Power Management | Diagnostic Information and Procedures | Document ID: 5493975 Diagnostic Instructions Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach. Diagnostic Procedure Instructions provides an overview of each diagnostic category. DTC Descriptors On/Off Vehicle Switch Voltage DTC B1B15 For symptom byte information refer to Symptom Byte List Diagnostic Fault Information

Circuit Number	Circuit Function	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performanc
5723	Control	B1B15 11	B1B15 15	B1B15 15	B1B15 2A
1851	Ground	—	B1B15 15	—	—

Circuit/System Description The S38 On/Off Vehicle Switch contains two individual switches that provide redundant switch inputs to both the K9 Body Control Module (BCM) (Power Mode Master)and the K56 Serial Data Gateway Module (Back Up Power Mode Master). The K9 Body Control Module supplies the S38 On/Off Vehicle Switch a constant 5 v signal on Signal Circuit  5723. The K9 Body Control Module monitors this signal to determine if the switch is released or pressed. When the S38 On/Off Vehicle Switch is not pressed, voltage on the signal circuit 5723 is pulled down through two resistors in the switch by ground circuit 1851. When the S38 On/Off Vehicle Switch is pressed, voltage on the signal circuit 5723 is pulled down through only one resistor by ground circuit 1851, the voltage change seen by the K9 Body Control Module indicates that the S38 On/Off Vehicle Switch is pressed. If a fault is detected on signal circuit 5723 or ground circuit 1851 a DTC will set. The K56 Serial Data Gateway Module supplies the S38 On/Off Vehicle Switch with a 5 v on signal circuit 3558 while the module is awake & low reference circuit 3559. The K56 Serial Data Gateway Module monitors this signal to determine if the switch is released or pressed. When the S38 On/Off Vehicle Switch is not pressed, voltage on the signal circuit 3558 is pulled down through two resistors in the switch by low reference circuit  3559. When the S38 On/Off Vehicle Switch is pressed, voltage on the signal circuit 3558 is pulled down through only one resistor in the switch by low reference circuit 3559, the changing the voltage seen at the K56 Serial Data Gateway Module indicates that the S38 On/Off Vehicle Switch is pressed. The K56 Serial Data Gateway Module is the vehicles backup power mode master. If a fault is detected on signal circuit 3558 or low reference circuit 3559 a DTC will set. The S38 On/Off Vehicle Switch has two LEDs that indicate the vehicle power mode. When the vehicle is in the off mode, both LEDs will be off. Pressing the S38 On/Off Vehicle Switch button momentarily without the brake pedal applied, the vehicle will enter the accessory mode, the K9 Body Control Module supplies a pulse width modulated voltage on control circuit 5720 to illuminate the amber LED (accessory), the LED is grounded through the switch by ground circuit 1851. The accessory mode has a time-out up to 5 min to help reduce battery drain. Pressing and holding the push button start switch without the brake pedal applied for 5  s will place the vehicle in Run Mode (Ignition On without the Propulsion Mode), the K9 Body Control Module supplies a pulse width modulated voltage on control circuit 5719 to illuminate the green LED (Run/Start/Propulsion), the LED is grounded through the switch by ground circuit 1851. With the ignition off brake pedal applied, pressing the S38 On/Off Vehicle Switch button once, the vehicle will enter Vehicle Start/Propulsion Mode this will start the Propulsion system, the K9 Body Control Module supplies a pulse width modulated voltage on control circuit 5719 to illuminate the green LED (Run/Start), the LED is grounded through the switch by ground circuit 1851. If the vehicle is in Propulsion Mode and vehicle speed above 4 km/h (2.5 mph) is detected and the S38  On/Off Vehicle Switch is pressed for greater than 2 s or is pressed 2 times within 5 s the vehicle will enter the Run Mode (Ignition On without the Propulsion Mode). C diti f R i th DTC Conditions for Running the DTC Ignition On or Propulsion Mode Control module voltage is 9–16 V. Conditions for Setting the DTC B1B15 2A The control module detects a continuously closed On/Off Vehicle Switch. The above condition exists for more than 1 min. B1B15 11 The control module detects a short to ground in the On/Off Vehicle Switch signal circuit 5723. The above condition exists for more than 1 s. B1B15 15 The control module detects an open in the On/Off Vehicle Switch signal circuit 5723 or ground circuit  1851. The above condition exists for more than 1 s. Action Taken When the DTC Sets B1B15 2A, B1B15 11, B1B15 15 The S38 On/Off Vehicle Switch Signal Voltage circuit 5723 to the K9 Body control Module will be ignored until the fault is corrected and the Passive Start Switch Signal 2 Input circuit 3558 to the K56 Serial Data Gateway Module (Back-Up Power mode Master) will take over to power mode the vehicle. Conditions for Clearing the DTC A current DTC clears when the malfunction is no longer present. A history DTC clears after 40 consecutive module ignition cycles without a repeat of the malfunction. Diagnostic Aids The S38 On/Off Vehicle switch is a mechanical switch and a sticking or binding condition may cause a plausibility DTC. The S38 On/Off Vehicle Switch Voltage when the switch is not pressed is between 3.34 and 4.26 V. The S38 On/Off Vehicle Switch Voltage when the switch is pressed is between 1.43 and 2.97 V. If the voltage detected on the S38 On/Off Vehicle switch is less than 1.42 V for more than 2 seconds a short to ground DTC will set. If the voltage detected on the S38 On/Off Vehicle switch is greater than 4.26 V for more than 2 seconds an open/short to voltage DTC will set.

Note

The circuit numbers listed below are a general overview and may not reflect the schematics for this document. The last 2 digits of the circuit number are significant in identifying its power and/or ground function. – Circuits ending in 42 are primary fused B+ circuits (generally the first fuse in the circuit after the battery) – Circuits ending in 40 are secondary fused circuits (generally fuses in a fuse block after the primary circuit) – Circuits ending in 39 and 41 are ignition voltage circuits. – Circuits ending in 50 are grounds. – Circuits ending in 51 are low reference (ground). Reference Information Schematic Reference Power Moding Schematics Power Distribution Schematics Connector End View Reference Master Electrical Component List Power Mode Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Scan Tool Reference Control Module References for scan tool information Circuit/System Verification

1. Verify DTC B1B42 is not set. ⇒ If DTC B1B42 is set Refer to: DTC B1B42 ⇓ If DTC B1B42 is not set
2. Refer to Circuit/System Testing. Circuit/System Testing
3. Ignition OFF, disconnect the connector at the S38 On/Off Vehicle Switch.

Note

If the S38 Vehicle On/Off Amber and/or Green indicators function this step does not need to be performed and you may proceed to the next step.

2. Verify a test lamp illuminates between the ground terminal 3 and B+ ⇒ If the test lamp does not illuminate Repair the open or high resistance on ground circuit 1851 or the ground connection. ⇓ If the test lamp illuminates
3. Connect the connector at the S38 On/Off Vehicle Switch.
4. Ignition On Vehicle in Run mode.
5. Disconnect the S38 On/Off Vehicle Switch.
6. Test for between 4.7 V and 5.3 V between the signal circuit terminal 4 and ground. ⇒ If not the specified value

Note

It may be necessary to disconnect the K9 Body control Module and K56 Serial Data Gateway Module when diagnosing a short on control circuit 5723. 6.1. Test the signal circuit 5723 for a short to ground condition. ⇒ If a short to ground condition is found, repair the short in the circuit. ⇓ If a short to ground condition is not found 6.2. Test the signal circuit 5723 for an open/high resistance condition. ⇒ If an open/high resistance condition is found, repair the open/high resistance in the circuit. ⇓ If an open/high resistance condition is not found 6.3. Test the signal circuit 5723 for less than 5.9 V. ⇒ If greater than 5.9 V, repair the short to voltage in the circuit. ⇓ If less than 5.9 V 6.4. Replace the K9 Body Control Module. ⇓ If the Specified Value

7. Ignition OFF, disconnect the connector at the S38 On/Off Vehicle Switch.
8. Test for 6.0k-7.5K Ω between Signal terminal 4 and ground terminal 3 with the S38 On/Off Vehicle not pressed. ⇒ If not between 6.0k-7.5K Ω Replace the S38 On/Off Vehicle Switch. ⇓ If between 6.0k-7.5K Ω
9. Press and hold the S38 On/Off Vehicle Switch.
10. .Test for 1.3k-1.8k Ω between Signal terminal 4 and ground terminal 3. ⇒ If not between 1.3k-1.8k Ω Replace the S38 On/Off Vehicle Switch. ⇓ If between 1.3k-1.8k Ω
11. Replace the K9 Body Control Module. Component Testing
12. Ignition OFF, disconnect the harness connector at the S38 On/Off Vehicle Switch.
13. Test for 6.0k-7.4k Ω between the terminals listed below with the S38 On/Off Vehicle Switch released, Signal terminal 4 and ground terminal 3 Signal terminal 8 and low reference terminal 7 ⇒ If not between 6.0k-7.4k Ω Replace the S38 On/Off Vehicle Switch. ⇓ If between 6.0k-7.4k Ω
14. Test for 1.4k–1.7k Ω between the terminals listed below with the S38 On/Off Vehicle Switch pressed. Signal terminal 4 and ground terminal 3 Signal terminal 8 and low reference terminal 7 ⇒ If not between 1.4k–1.7k Ω Replace the S38 On/Off Vehicle Switch. ⇓ If between 1.4k–1.7k Ω
15. A fault is not currently present and may be an intermittent condition. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification On/Off Vehicle Switch Replacement For control module replacement, programming, and setup refer to: Control Module References