B108A:01
Diagnostic Routine J
Diagnostic Overview
B108A:01 or B1142:29
Refer to Wiring Diagram Set 13 for schematic and connector information Electrical Diagrams.
Normal Operation and Fault Conditions
On vehicles equipped with a conventional ignition switch, fused battery voltage is sent to the ignition switch from BCM (Body Control Module) fuse 28 (15A). This voltage is then sent to the BCM (Body Control Module) along 1 of 3 circuits, depending on ignition switch position.
On vehicles equipped with a start/stop switch, fused battery voltage is sent to one set of contacts in the start/stop switch from BCM (Body Control Module) fuse 28 (15A). When the switch is pressed, this voltage is then sent to the BCM (Body Control Module), the RFA (Remote Function Actuator) module and the PCM (Powertrain Control Module). The other set of contacts in the start/stop switch connects the BCM (Body Control Module) to ground. When the switch is pressed, the BCM (Body Control Module) detects this ground signal and takes appropriate action.
DTC Fault Trigger Conditions
Visual Inspection and Diagnostic Pre-checks
Make sure BCM (Body Control Module) fuse 28 (15A) is OK.
Pinpoint Test
1. IDENTIFY THE IGNITION SYSTEM
1. Verify that the vehicle is equipped with a start/stop switch.
Is the vehicle equipped with a start/stop switch?
2. CHECK THE IGNITION SWITCH STATE (IGN_SW_STATE) PID (Parameter Identification)
1. Ignition ON.
2. Using a scan tool, view the BCM (Body Control Module) PIDs (Parameter Identifications).
3. Monitor the IGN_SW_STATE PID (Parameter Identification) while turning the ignition switch through all 4 positions (OFF, ACC, RUN and START).
Does the PID (Parameter Identification) match each ignition switch position?
3. CHECK THE ACC CIRCUIT FOR AN OPEN OR SHORT TO VOLTAGE
1. Ignition ACC.
2. Monitor the IGN_SW_STATE PID with the ignition switch in the ACC position.
Does the PID (Parameter Identification) display "Acc"?
4. CHECK THE RUN CIRCUIT FOR AN OPEN OR SHORT TO VOLTAGE
1. Ignition ON.
2. Monitor the IGN_SW_STATE PID (Parameter Identification) with the ignition switch in the RUN position.
Does the PID (Parameter Identification) display "Run"?
5. CHECK THE START CIRCUIT FOR AN OPEN OR SHORT TO VOLTAGE
1. Monitor the IGN_SW_STATE PID (Parameter Identification) with the ignition switch in the START position.
Does the PID (Parameter Identification) display "Start"?
6. CHECK FOR RFA (Remote Function Actuator) MODULE DTCs (Diagnostic Trouble Codes)
1. Using a scan tool, perform RFA (Remote Function Actuator) module self-test to retrieve DTCs (Diagnostic Trouble Codes).
2. Record all RFA (Remote Function Actuator) module DTCs (Diagnostic Trouble Codes).
Is DTC (Diagnostic Trouble Code) B108A:12 present?
7. CHECK THE START/STOP SWITCH
1. Disconnect: Start/stop Switch.
2. Carry out the start/stop switch component test.
Does the switch pass the test?
8. CHECK FOR VOLTAGE TO THE START/STOP SWITCH
1. Measure:
Is the voltage greater than 11 volts?
9. CHECK THE START/STOP SWITCH VOLTAGE INPUT CIRCUIT FOR AN OPEN
1. Disconnect: BCM (Body Control Module) C2280B.
2. Measure:
Is the resistance less than 3 ohms?
10. CHECK THE BCM (Body Control Module) START/STOP SWITCH GROUND INPUT CIRCUIT FOR AN OPEN
1. Measure:
Is the resistance less than 3 ohms?
11. CHECK THE BCM (Body Control Module) START/STOP SWITCH GROUND INPUT CIRCUIT FOR A SHORT TO GROUND
1. Measure:
Is the resistance to ground greater than 10,000 ohms?
12. CHECK THE START/STOP SWITCH GROUND CIRCUIT FOR AN OPEN
1. Measure:
Is the resistance less than 3 ohms?
13. CHECK FOR CORRECT BCM (Body Control Module) OPERATION
1. Disconnect and inspect all BCM (Body Control Module) connectors.
2. Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary
3. Reconnect the BCM (Body Control Module) connectors and all previously disconnected exterior system connectors. Make sure they seat and latch correctly.
4. Operate the system and determine if the concern is still present.
Is the concern still present?
