Blind Spot Information System - System Operation and Component Description: Notes

System Operation

BLIS® and CTA 

System Diagram 

Courtesy of FORD MOTOR COMPANY

Network Message Chart 

IPC Network Input Messages 

ACM Network Input Messages 

DSP Network Input Messages 

DDM Network Input Messages 

PDM Network Input Messages 

SODL Network Input Messages 

SODR Network Input Messages 

BLIS® 

The BLIS® provides alerts to the driver when the vehicle is in a forward gear and the vehicle speeds is greater than 10 km/h (6 mph).

The BLIS® can trigger an alert for vehicles that enter the blind zone from the rear, front, or merge into the blind zone from the side. The exterior mirror BLIS®/ CTALED illuminates in the right and/or left exterior mirror when a target is present. For vehicles that pass through the blind zone quickly, typically less than 2 seconds, the BLIS® may not trigger an alert.

If a turn signal is active while BLIS® has detected a target in the blind zone, the BLIS®/ CTALED flashes rapidly. When the turn signal is off, the BLIS® target warnings are a constant LED illumination.

Due to the nature of radar technology, false alerts may occur under certain circumstances. False alerts occur when the LED illuminates with no target present. False alerts up to 3% (3 out of 100 targets) is considered normal operation. False alerts are temporary and self-correcting. False alerts may be caused by sharp turns around a pole or building, jogging pedestrians or fast moving shopping carts.

Missed targets occur when a target is present and the LED does not illuminate. Missed targets up to 1% (1 out of 100 targets) is considered normal operation.

Circumstances that cause missed alerts are: 

• Debris build-up or damage to the rear lamp assemblies
• Certain maneuvering of the vehicles entering and exiting the blind zone
• Vehicles passing through the blind zone at high rates of speed
• When several vehicles forming a convoy pass through the blind zone

The BLIS® may not detect an adjacent target immediately when the vehicle accelerates from a standing start with another vehicle alongside.

BLIS® with Trailer Tow (BTT) 

The BLIS® with Trailer Tow can be turned off through the IPC message center. If the BLIS® is turned off, then the BLIS® with Trailer Tow automatically turns off.

The following steps should be performed when setting up a trailer through the IPC message center: 

• Select the type of trailer: conventional, 5th wheel or gooseneck. If 5th wheel or gooseneck is selected then BLIS® and CTA functions will turn off.
• Select whether or not the width of the new trailer is less than or equal to 2.6 m (8.5 ft).
• Enter the length of the new trailer. The length is measured between the trailer ball hitch and the back of the trailer. BLIS® with Trailer Tow should turn on and CTA turn off. However, if the trailer length is entered as 3 feet, then CTA remain on (3 feet length is reserved for bike racks and cargo racks).

When the trailer is first connected a message appear in the IPC message center that says "Trailer connected". When connecting to a four pin trailer connector the brake pedal must be depressed immediately afterwards in order to get the "Trailer connected" message. If a preset trailer exists in the IPC then BLIS® with Trailer Tow automatically receives preset trailer information. If the trailer just connected is not the preset trailer, then select the correct trailer from the IPC menu or add a new trailer with the correct dimensions. If there are no preset trailers in the IPC, then the IPC automatically request trailer information. If at this point the driver exits the message center menus, then BLIS® and CTA automatically turn off. Otherwise, the driver must add new trailer information through the IPC.

False alerts are possible with a truck and trailer operating with BLIS® with Trailer Tow. If the ignition is cycled, the BLIS® with Trailer Tow continues to function using the last trailer selected.

The BLIS® with Trailer Tow is designed to work with any trailer whose front width is 2.6 m (8.5 ft) or less and the total length from the trailer hitch ball to the rear of the trailer is 10 m (33 ft) or less. Different trailers may cause a slight change in performance as outlined below.

• Large box trailers may cause false alerts to trigger when driving next to buildings or near parked cars.
• A false alert may also occur while making a 90-degree turns.
• Trailers that are 2.6 m (8.5 ft) wide at the front and have a total length greater than 6 m (20 ft) may have delayed alerts from passing vehicles when the vehicle is passing at high speed.
• A box trailer whose front width is 2.6 m (8.5 ft) may cause early alerts when over taking a vehicle.

CTA System 

When the transmission is in reverse, the CTA system can detect a vehicle or a bicycle that is approaching at a speed between 8 km/h and 64 km/h (5 mph and 40 mph) and time to impact is between 1 and 2.5 seconds. The distance at which an alert is generated varies depending on the speed of the approaching vehicles or bicycles. The CTA system response time and performance can degrade if vehicles are approaching at speeds greater than 64 km/h (40 mph).

An adjacent parked vehicle or object can affect the systems ability to detect approaching vehicles or bicycles (refer to figure 1 below). Parking at extreme angles can further affect the systems ability to detect approaching vehicles or bicycles (refer to figure 2 below).

Backing towards a curve road can also affect systems ability to detect approaching vehicles or bicycles (refer to figure 3 below).

CTA detection zones: 

Courtesy of FORD MOTOR COMPANY

Courtesy of FORD MOTOR COMPANY

Courtesy of FORD MOTOR COMPANY

The CTA system is designed to detect any objects approaching the vehicle at a speed equal to or greater than 8 km/h (5 mph). This includes vehicles and bicycles. The CTA system has some detection limitations due to the nature of the radar technology used by the SODL and SODR. The system cannot normally detect stationary vehicles, humans, animals or objects such as fences, guard rails or trees.

Circumstances that may cause non-detection are: 

• Debris build-up or damage to the rear lamp assemblies
• The rear quarter panel of the vehicle is obstructed or partially obstructed by an adjacently parked vehicle or object
• Vehicle approaching at speeds greater than 64 km/h (40 mph)
• Driving in reverse faster than 12 km/h (8 mph)
• Damage to sensor and/or sensor area

Due to the nature of radar technology, there may be certain instances when the CTA system alerts the operator, when no object or vehicle is present while backing up. This is known as a false alert. False alerts up to 3% of the time (3 times out of 100 reversals) are considered normal. A false alert may occur when backing out of a garage or backing into a parking space and objects or vehicles are very close to the radar sensors. False alerts are temporary and self-correcting.

Missed targets occur when a target is present and the LED does not illuminate. Missed targets up to 1% (1 out of 100 targets) is considered normal operation.

Circumstances that cause missed alerts are: 

• Debris build-up or damage to the rear lamp assemblies
• Certain maneuvering of the vehicles entering and exiting the detection zone
• Vehicles passing through the detection zone at high rates of speed
• When several vehicles forming a convoy pass through the detection zone

Exterior Mirror Indication 

When the BLIS® or CTA system is active and an object is detected by the SODL or SODR, the BLIS®/ CTALED command message is sent from the SODL or SODR to the DDM or PDM. The DDM and PDM supply voltage and ground to illuminate their respective exterior mirror BLIS®/ CTALED based on messages received from the SODL and SODR.

Each time the vehicle is started, the SODL and SODR command the DDM and PDM to illuminate the exterior mirror BLIS®/ CTA Light Emitting Diodes (LEDs) for approximately 3 seconds, indicating the BLIS® and CTA system is operational.

If a BLIS® or CTA system fault is present, the exterior mirror BLIS®/ CTACTA Light Emitting Diodes (LEDs) remains off, the IPCBLIS® RTT illuminates and a message center warning displays BLIND SPOT SYSTEM FAULT.

BLIS® and CTA Message Center Function 

BLIS® can be turned off by using the blind spot on/off function in the message center. When the BLIS® has been turned off by the driver or if a system fault is present, the BLIS® RTT in the message center remains on. When turning the system on or off, the exterior mirror Light Emitting Diodes (LEDs) flash 2 times. When the BLIS® is turned off, the driver cannot receive any alerts. The system remains off until turned back on by the driver.

The CTA system can be turned off by selecting the CTA system on/off function in the message center. The system defaults to on with each ignition cycle.

There are some system faults that set Diagnostic Trouble Codes (DTCs) in the SODL, SODR, DDM or PDM. These Diagnostic Trouble Codes (DTCs) can set a message in the IPC message center that displays BLIND SPOT SYSTEM FAULT and/or CROSS TRAFFIC SYSTEM FAULT. There are also symptom based faults that do not set a DTC.

Blocked Sensor 

An excessive build-up of materials on the rear lamp assemblies, such as mud or snow, can cause the BLIS® or CTA system functionality to degrade. Heavy rain can have the same affect on the system. If a blocked state is detected, the SODL and SODR blockage sensing senses the performance degradation and enters the SODL and SODR into a blocked state. The performance degradation means alerting late on targets or additional missed targets. Upon entering a blocked state, the SODL and/or SODR send a status message over the MS-CAN to the GWM. The GWM then sends the status message to the IPC on the HS-CAN3. The message center displays BLIND SPOT NOT AVAILABLE SENSOR BLOCKED or CROSS TRAFFIC NOT AVAILABLE SENSOR BLOCKED and the LH and RH exterior mirror BLIS®/ CTA Light Emitting Diodes (LEDs) illuminate.

The message center warning can be cleared by the driver, but the amber BLIS® off RTT in the IPC remains illuminated. A blocked state will self-clear when blockage sensing senses performance has returned to normal operation. The ignition can also be cycled off to clear the blocked state. If the blockage is still present after the ignition cycle, or after some drive time the system detects again that it is blocked, the blocked sensor message is displayed again in the message center and the amber BLIS® off IPCRTT is illuminated again.

Due to the nature of radar technology, it is possible to get a blocked sensor warning without the radar sensor being blocked. This is rare and is known as a false blockage warning. A false blocked condition either self-clears or clears after an ignition cycle.