Pinpoint Test A: The Forward Collision Warning System Is Inoperative
Forward Collision Warning
Pinpoint Tests
Pinpoint Test A: The Forward Collision Warning System Is Inoperative
Refer to Wiring Diagram Set 136, Vehicle Emergency Messaging System for schematic and connector information. Diagrams By Number
Normal Operation
The forward collision warning system is enabled when the ignition switch is in the RUN position. The Smart Junction Box (SJB) sends a serial data ignition state message over the Medium Speed Controller Area Network (MS-CAN) to the Instrument Panel Cluster (IPC). The IPC then gateways the ignition state message to the HUD module over the High Speed Controller Area Network (HS-CAN). The LEDs that are internal to the HUD module illuminate for 3 seconds to indicate the system is operational. This is know as the bulb prove-out for the LEDs.
The radar sensor unit, which is integral to the Cruise-Control Module (C-CM), sends out a radar signal to the vehicle in the path of travel and receives the radar signal back to determines the distance and relative speed of that vehicle. The C-CM sends a serial data message via the HS-CAN to the HUD module if the vehicle in the path of travel enters the preset gap for a collision warning. The HUD module receives a serial data message from the C-CM to flash the LEDs. The C-CM also sends a serial data message to the IPC to activate a chime from the IPC and gateways a message over the MS-CAN to mute the Audio Control Module (ACM) volume. The system can be disabled through the IPC message center.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- C-CM
- HUD module
- IPC
PINPOINT TEST A: THE FORWARD COLLISION WARNING SYSTEM IS INOPERATIVE
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.
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A1 CHECK THE DTCs FROM THE CONTINUOUS AND ON-DEMAND HUD MODULE SELF-TESTS
- Check the HUD module DTCs from the continuous and on-demand self-tests.
- Are any HUD module DTCs recorded?
Yes
REFER to DTC Charts. Forward Collision Warning
No
GO to A2.
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A2 CHECK THE C-CM DTCs
- Check the C-CM DTCs from the continuous and on-demand self-tests.
- Are any C-CM DTCs recorded?
Yes
REFER to Fire Suppression System. REPAIR all C-CM DTCs. TEST the system for normal operation.
No
GO to A3.
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A3 CHECK THE MESSAGE CENTER FOR CORRECT OPERATION
- Check the IPC message center for correct operation.
- Does the message center operate correctly?
Yes
GO to A4.
No
REFER to Instrument Panel, Gauges and Warning Indicators to diagnose the IPC message center.
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A4 CHECK THE HUD MODULE VOLTAGE SUPPLY
- Ignition OFF.
- Disconnect: HUD Module C2395.
- Ignition ON.
- Measure the voltage between the HUD module C2395-5, circuit SBP26 (YE/RD), harness side and ground; and between the HUD module C2395-4, circuit CBP29 (WH/VT), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to A5.
No
VERIFY the Smart Junction Box (SJB) fuse 26 (10A) or 29 (5A) is OK. If OK, REPAIR the circuit for an open. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. TEST the system for normal operation. Diagrams By Number
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A5 CHECK THE HUD MODULE GROUND CIRCUIT
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the HUD module C2395-1, circuit GD114 (BK/BU), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to A6.
No
REPAIR the circuit for an open. TEST the system for normal operation.
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A6 CHECK FOR CORRECT HUD MODULE OPERATION
- Disconnect the HUD module connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the HUD module connector and make sure it seats correctly.
- Operate the system and determine if the concern is still present.
- Is the concern still present?
Yes
INSTALL a new HUD module. REFER to Head Up Display (HUD) Module Service and Repair. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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