Adaptive Cruise Control Problems

[kevin christensen]

Hello.  My new 2025 3500 has ACC.  I like it but it seems to glitch randomly.  What it does is suddenly break when no one is in front of me.  Only seems to happen on a bright sunny day.  I've not experienced it at night or when it's overcast (although the days are long and sunny this time of year).  For these reasons, I thought the problem may be somehow related to shadows crossing the road.  However, I took a long road trip on I-90 where there were no shadows across the road and it still did it a few times.  Not as often as the shady country roads I usually travel.  I keep the grill camera and sensor clean, as well as the windshield.  Anyone else experience this?

[redwngr]

If it gets 'blinded' by bright light it will kick out.

Should also be a message that 'adaptive cruise is unavailable' (or similar) 

 

Same type of conditions that cause a driver grief --like driving towards sun when it is low in the sky or bright reflections from a building or another vehicle. 

 

it can be switched to regular cruise if the condition is expected to continue. 

Edited August 11, 2025 by redwngr

[newdude]

1 hour ago, kevin christensen said:

Hello.  My new 2025 3500 has ACC.  I like it but it seems to glitch randomly.  What it does is suddenly break when no one is in front of me.  Only seems to happen on a bright sunny day.  I've not experienced it at night or when it's overcast (although the days are long and sunny this time of year).  For these reasons, I thought the problem may be somehow related to shadows crossing the road.  However, I took a long road trip on I-90 where there were no shadows across the road and it still did it a few times.  Not as often as the shady country roads I usually travel.  I keep the grill camera and sensor clean, as well as the windshield.  Anyone else experience this?

 

 

Grill camera has nothing to do with ACC.  That is the front view camera for the 360 surround display.  No "sensors" either.  Front sensors on the bumper are forward parking assist sensors.  

 

One entity operates ACC information and its just the forward collision camera at the top center of the windshield.  That camera is also in talks with the Body Control Module, Engine Control Module, Brake System Control Module, Instrument Cluster, Cruise Control Switch and gap adjustment switch.  

 

Limitations and reasons it may act certain ways:

Safety Considerations

• The system can only apply limited braking. The driver’s complete attention is always required while driving
• The system may not react to parked, stopped or slow-moving vehicles; the driver should always be ready to take action and apply the brakes
• Driver should not use adaptive cruise control on winding or hilly roads, on freeway exit or entrance ramps or when trailering. In these driving conditions, the system may not detect the vehicle ahead
• The system cannot detect traffic lights or traffic signs, so the driver needs to safely brake accordingly whenever approaching an intersection with a traffic light or stop sign
• If no vehicle ahead is detected, adaptive cruise control will work like regular cruise control
• When using adaptive cruise control, the driver should keep in mind that the system is designed to follow detected vehicles ahead at a longer distance when traveling at higher speeds than at lower speeds
• To avoid using adaptive cruise control by accident, advise customers to keep the cruise control button off when they don’t need it. They should press the ON/OFF button and verify that the adaptive cruise control icon is not lit

 

Adaptive cruise control may have difficulty detecting the following objects:

• Vehicles in front of the driver’s vehicle that have a rear aspect that is low, small or irregular
• A truck or trailer that has no cargo in the cargo bed
• Vehicles with cargo extending from the back end
• Non-standard shaped vehicles, such as vehicle transport, vehicles with a sidecar or horse carriages
• Vehicles that are low to the road surface
• Objects that are close to the front of the driver’s vehicle

 

Weather conditions can affect adaptive cruise control:

• If the vehicle’s interior temperature is extremely high, the P16 Instrument Cluster may indicate that adaptive cruise control is temporarily unavailable. This can be caused by extreme hot weather conditions with direct sunlight on the front camera. Adaptive cruise control will return to normal operation once the cabin temperature is cooler
• Conditions that are associated with low visibility, such as fog, rain, snow or road spray, may limit the performance of adaptive cruise control. Water droplets from rain or snow that remain on the windshield may also limit adaptive cruise control’s ability to detect objects

 

The B174W Frontview Camera – Windshield can be hampered by poor lighting conditions, including when:

• Multiple changes in brightness, such as shadows along the roadway, entering and exiting tunnels, or bridges and overpasses
• Low sun angles may cause the camera to not detect objects, or make it more difficult to detect objects in the same lane
• Lighting is poor in the evening or early morning
• The vehicle is in a tunnel without the headlamps on, or in a tunnel when there is a vehicle ahead that does not have its taillamps on
• The vehicle is subjected to strong light from the oncoming opposing lane traffic, such as high-beam headlamps from oncoming traffic

[Tom73]

The sun plays havoc with my ACC. When the sun hits the cameras at the correct angle it will shut things down. So if it happen when you are going towards the sun, that is the issue. But if it happens going away from the sun it is probably other issues. 

[matt99199]

On 8/11/2025 at 5:10 PM, newdude said:

 

 

Grill camera has nothing to do with ACC.  That is the front view camera for the 360 surround display.  No "sensors" either.  Front sensors on the bumper are forward parking assist sensors.  

 

One entity operates ACC information and its just the forward collision camera at the top center of the windshield.  That camera is also in talks with the Body Control Module, Engine Control Module, Brake System Control Module, Instrument Cluster, Cruise Control Switch and gap adjustment switch.  

 

Limitations and reasons it may act certain ways:

Safety Considerations

• The system can only apply limited braking. The driver’s complete attention is always required while driving
• The system may not react to parked, stopped or slow-moving vehicles; the driver should always be ready to take action and apply the brakes
• Driver should not use adaptive cruise control on winding or hilly roads, on freeway exit or entrance ramps or when trailering. In these driving conditions, the system may not detect the vehicle ahead
• The system cannot detect traffic lights or traffic signs, so the driver needs to safely brake accordingly whenever approaching an intersection with a traffic light or stop sign
• If no vehicle ahead is detected, adaptive cruise control will work like regular cruise control
• When using adaptive cruise control, the driver should keep in mind that the system is designed to follow detected vehicles ahead at a longer distance when traveling at higher speeds than at lower speeds
• To avoid using adaptive cruise control by accident, advise customers to keep the cruise control button off when they don’t need it. They should press the ON/OFF button and verify that the adaptive cruise control icon is not lit

 

Adaptive cruise control may have difficulty detecting the following objects:

• Vehicles in front of the driver’s vehicle that have a rear aspect that is low, small or irregular
• A truck or trailer that has no cargo in the cargo bed
• Vehicles with cargo extending from the back end
• Non-standard shaped vehicles, such as vehicle transport, vehicles with a sidecar or horse carriages
• Vehicles that are low to the road surface
• Objects that are close to the front of the driver’s vehicle

 

Weather conditions can affect adaptive cruise control:

• If the vehicle’s interior temperature is extremely high, the P16 Instrument Cluster may indicate that adaptive cruise control is temporarily unavailable. This can be caused by extreme hot weather conditions with direct sunlight on the front camera. Adaptive cruise control will return to normal operation once the cabin temperature is cooler
• Conditions that are associated with low visibility, such as fog, rain, snow or road spray, may limit the performance of adaptive cruise control. Water droplets from rain or snow that remain on the windshield may also limit adaptive cruise control’s ability to detect objects

 

The B174W Frontview Camera – Windshield can be hampered by poor lighting conditions, including when:

• Multiple changes in brightness, such as shadows along the roadway, entering and exiting tunnels, or bridges and overpasses
• Low sun angles may cause the camera to not detect objects, or make it more difficult to detect objects in the same lane
• Lighting is poor in the evening or early morning
• The vehicle is in a tunnel without the headlamps on, or in a tunnel when there is a vehicle ahead that does not have its taillamps on
• The vehicle is subjected to strong light from the oncoming opposing lane traffic, such as high-beam headlamps from oncoming traffic

This is partially wrong, there is a forward facing radar in the bumper that is also apart of the ACC system with the windshield camera. Not that it matters but it is a fusion of the two.

Edited November 15, 2025 by matt99199

[newdude]

1 hour ago, matt99199 said:

This is partially wrong, there is a forward facing radar in the bumper that is also apart of the ACC system with the windshield camera. Not that it matters but it is a fusion of the two.

 

 

Forward radar is only if you have Super Cruise.

 

Regular Adaptive Cruise Control doesn't use any radar, just the forward windshield camera. 

 

If equipped with Super Cruise, ACC will use both the windshield camera and the long range radar module.  

 

Description and operation for the 2022.5-up 1/2 ton and 2024-up HD.  I've bolded the main list of components used by ACC.  Note there is no radar modules :

 

Adaptive Cruise Control Components

The adaptive cruise control functionality depends on various switches and control modules on the vehicle to function. Each component performs a function that is critical to the proper operation of the adaptive cruise control system. Adaptive cruise control will not operate if any single component has a fault. Communication between modules is via serial data. The following is a functional description of the B174W Frontview Camera – Windshield and the other associated components:

 

• Frontview Camera – Windshield
• K9 Body Control Module
• K20 Engine Control Module
• K17 Electronic Brake Control Module (if equipped)
• K160 Brake System Control Module (if equipped)
• P16 Instrument Cluster
• Cruise Control Switch
• Adaptive Cruise Control Gap Switch

 

B174W Frontview Camera – Windshield

The B174W Frontview Camera – Windshield analyzes data from various modules, sensors, and switches to provide enhanced safety features. In addition to enhanced safety features, the B174W Frontview Camera – Windshield provides the adaptive cruise control system functionality. The B174W Frontview Camera – Windshield utilizes it’s own camera and internal logic to identify and classify objects in the road environment. The system scans the road environment to detect targets within its specified field of view. The B174W Frontview Camera – Windshield then sends throttle and/or brake commands to the K20 Engine Control Module and K17 Electronic Brake Control Module or K160 Brake System Control Module via serial data in order to control the vehicle acceleration/deceleration based on the data from the modules. The K20 Engine Control Module and K17 Electronic Brake Control Module or K160 Brake System Control Module provide throttle control and automatic braking needed for proper speed and braking adjustment. The following is a list of the B174W Frontview Camera – Windshield pertaining to the adaptive cruise control functionality:

 

• Processes the road environment to get data concerning any vehicle ahead of the adaptive cruise control vehicle. Detection, parameter estimation, tracking, object classification and diagnostics are the primary functions. When an object is detected, the B174W Frontview Camera – Windshield calculates the object range, range rate, acceleration and azimuth angle parameters.
• Performs adaptive cruise control distance control or speed control processing automatically. The adaptive cruise control operates in two possible states – cruise or follow. The normal operating state is cruise, whereby the vehicle speed is controlled to match the driver selected set speed. When a preceding vehicle is identified, the adaptive cruise control system will automatically transition into the follow speed state to provide proper lane spacing behind the target vehicle in front. The preceding vehicle's speed and acceleration, with the adaptive cruise control vehicle speed, acceleration and distance between the two vehicles will be used to determine the adaptive cruise control follow speed limit. The adaptive cruise control follow speed limit will ensure that an acceptable distance is maintained to the preceding vehicle.
• Determines the follow speed limit for throttle control by the K20 Engine Control Module and arbitrates the brake and throttle control between the K17 Electronic Brake Control Module or K160 Brake System Control Module and the K20 Engine Control Module.
• Requests brake light activation during automatic braking.
• Provides operational feedback to the vehicle driver. The B174W Frontview Camera – Windshield sends signals for telltales and messages to be displayed on the P16 Instrument Cluster or driver information center.

 

K9 Body Control Module

The following are the adaptive cruise control System functions provided by the K9 Body Control Module:

 

• Monitors all cruise control switches and the adaptive cruise control gap switch. The K9 Body Control Module relays the switch status to the B174W Frontview Camera – Windshield via serial data.
• Illuminates the brake light based on a serial data message from the B174W Frontview Camera – Windshield during automatic braking.
• Measures the brake pedal position and sends brake pedal travel status via serial data circuit to the K20 Engine Control Module. The K20 Engine Control Module disengages the adaptive cruise control system when the driver presses the brake pedal.

 

K20 Engine Control Module

The following are the adaptive cruise control system functions performed by the K20 Engine Control Module:

 

• Provides the electronic throttle control to the adaptive cruise control System. The K20 Engine Control Module is also responsible for determining when a driver is overriding the adaptive cruise control throttle position by pressing the accelerator pedal.
• Processes the cruise control switch requests received via serial data circuit from the K9 Body Control Module. Engaging and disengaging the adaptive cruise control system are functions performed by the K20 Engine Control Module.
• Determines the driver selected vehicle speed. Unless the adaptive cruise control module requests a lower vehicle speed, the K20 Engine Control Module will control the vehicle speed to the driver selected set speed.
• Allows automatic braking without disengaging the adaptive cruise control.

 

K17 Electronic Brake Control Module (if equipped)

The following are the adaptive cruise control System functions performed by the K17 Electronic Brake Control Module:

 

• Provides automatic braking for the adaptive cruise control system. The B174W Frontview Camera – Windshield will request vehicle deceleration via serial data circuit.
• Releases vehicle automatic braking when there is a throttle override by the driver pressing the accelerator.
• Predicts brake temperatures. Excessive automatic braking may cause, the brake system may overheat. When the brakes are overheated, the K17 Electronic Brake Control Module requests the adaptive cruise control system to be temporarily disabled until the brakes cool to a normal operating temperature.

 

K160 Brake System Control Module (if equipped)

The following are the adaptive cruise control system functions performed by the K160 Brake System Control Module:

 

• Provides automatic braking for the adaptive cruise control system. The B174W Frontview Camera – Windshield will request vehicle deceleration via serial data circuit.
• Releases vehicle automatic braking when there is a throttle override by the driver pressing the accelerator.
• Predicts brake temperatures. Excessive automatic braking may cause, the brake system may overheat. When the brakes are overheated, the K160 Brake System Control Module requests the adaptive cruise control system to be temporarily disabled until the brakes cool to a normal operating temperature.

 

P16 Instrument Cluster

The driver information center is a part of the P16 Instrument Cluster and displays the adaptive cruise control system warning messages. The B174W Frontview Camera – Windshield requests messages to be displayed on the driver information center by sending a serial data request. When the message is acknowledged by the driver and the cause of the message resolved, the driver information center turns the message off. The adaptive cruise control system will not operate if the driver information center has a fault.

 

Cruise Control Switch

The cruise control switch function is a common feature that is shared between the adaptive cruise control system and the regular cruise control system. The adaptive cruise control system will not operate if any cruise control switch fault exists. The cruise control switch is made up of the following cruise control function switches:

 

• On/Off switch
• Set/decrease switch
• Resume/increase switch

The cruise control function switches are arranged in a resistor ladder design whereby each switch function is has a different resistance value. The K9 Body Control Module provides a constant voltage reference to the cruise control switches and monitors switch feedback from a specific signal circuit. When a button is pressed, the voltage monitored on the signal circuit changes based on the number of resistors in the resistor ladder. The K9 Body Control Module recognizes this voltage as a specific cruise control switch function. The associated cruise control function detected by the K9 Body Control Module is then sent to the K20 Engine Control Module as a serial data circuit message. On receiving the message, the K20 Engine Control Module provides the cruise control function requested by the K9 Body Control Module. The K20 Engine Control Module is responsible for recognizing and responding to cruise control switch requests sent by the K9 Body Control Module. The cruise control function switches are used by the K20 Engine Control Module to communicate to the B174W Frontview Camera – Windshield the driver selected vehicle speed. The driver selected vehicle speed is communicated through serial data circuit to the B174W Frontview Camera – Windshield and the K9 Body Control Module. The adaptive cruise control system engages and adjusts vehicle speeds based on the activation of the following cruise control function switches:

 

Adaptive Cruise Control Gap Switch

The gap switch allows the driver to determine how closely the adaptive cruise control vehicle follows a target vehicle while adaptive cruise control is engaged. When the adaptive cruise control vehicle speed is being limited due to a slower travelling vehicle, the adaptive cruise control vehicle speed is automatically controlled to the follow distance. The gap switch has three following distance selections that range from near to far. The distance maintained for a selected gap will vary based on vehicle speed: The faster the vehicle speed, the greater the gap. The gap setting can only be adjusted when the adaptive cruise control system is engaged.

The gap switch is a momentary switch located as part of the cruise control switch assembly. The gap switch is located in a resistor ladder. The K9 Body Control Module provides a constant voltage reference to the gap switch and monitors switch feedback from a specific signal circuit. When the gap switch button is pressed, the voltage monitored on the signal circuit changes based on the number of resistors in the resistor ladder. The K9 Body Control Module recognizes this voltage as the gap switch function. The gap switch is detected by the K9 Body Control Module and then sent to the K20 Engine Control Module and B174W Frontview Camera – Windshield as a serial data message. After receiving the message, the K20 Engine Control Module and B174W Frontview Camera – Windshield will adjust the following distance based on the driver selected setting.

Edited November 15, 2025 by newdude