MAZDA RADAR CRUISE CONTROL (MRCC) SYSTEM [MAZDA RADAR CRUISE CONTROL (MRCC) SYSTEM]

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Outline

•  The Mazda Radar Cruise Control (MRCC) system uses a radar sensor to detect vehicles ahead so that a set vehicle speed and distance from a vehicle ahead can be maintained without the driver having to depress the accelerator or brake pedals. Additionally, if the driver of a vehicle ahead applies the brakes suddenly and is approached too closely, the system alerts the driver using a warning sound and warning indication.
Warning
•  Do not rely completely on the MRCC system and always drive carefully. There are limitations to the distance between the vehicles which can be controlled by the MRCC system, and if the accelerator pedal or brake pedal is mistakenly operated it could result in an accident. Always verify the safety of the surrounding area and depress the brake pedal while keeping a safe distance from the vehicle ahead.
•  The MRCC system does not completely stop the vehicle using the automatic braking operation. Additionally, brake control is performed, however, there are limitations to the deceleration, and the system may be unable to decelerate sufficiently to avoid hitting the vehicle ahead if the vehicle ahead applies the brakes suddenly or another vehicle cuts into the driving lane, which could result in an accident. Always verify the safety of the surrounding area and depress the brake pedal while keeping a safe distance from the vehicle ahead.

Structural View

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System Wiring Diagram

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Block diagram

•  Performs signal input/output between the vehicle control module (V/C-module) and related modules using CAN communication.
•  Signal input/output between the vehicle control module (V/C-module) and the radar sensor is performed using local CAN communication.

Block diagram (MRCC/SBS/DRSS)

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Function

•  The MRCC system is equipped with the following indicated modes.
―  Constant speed control mode: Travel at set speed.
―  Headway control mode: Headway control with vehicle ahead within set vehicle speed

System conditions display function

•  The vehicle control module (V/C-module) displays the MRCC indicator light (green)/warning light (amber), and the SBS/SCBS indicator light (amber)/warning light (red) in the instrument cluster, and it displays the system conditions in the active driving display.

Condition

MRCC indicator light (green)

MRCC warning light (amber)

SBS/SCBS warning light (amber)

SBS/SCBS indicator light (Red)

Active driving display indication
MRCC system is OFF
Off
Off
Off
Off
No display
MRCC system is ON
MRCC system is on standby
Off
Off
Off
Off
Vehicle speed is set
On
Off
Off
Off
Vehicle ahead is detected
On
Off
Off
Off
Distance between vehicles is set
Long
On
Off
Off
Off
Medium
On
Off
Off
Off
Short
On
Off
Off
Off
Extremely short
On
Off
Off
Off
Deceleration exceeding system limits required
On
Off
Off
Flash
Shift up/down required (MTX)
On
Off
Off
Off
•  MRCC system is automatically canceled due to low vehicle speed
•  MRCC is system canceled by driver
Off
Off
Off
Off
Dirty radar sensor is detected
Off
Off
On
Off
No display
Malfunction occurred in MRCC system
Off
Flash
Off
Off
No display


Operation

•  The MRCC system operates when all of the following conditions are met.
Operation conditions
―  Selector lever is in D or M position (ATX)
―  Shift lever is in position other than R or N position (MTX)
―  Vehicle speed is within range of approx. 30—200 km/h {19—124 mph} (European (L.H.D. U.K.) specs.)
―  Vehicle speed is within range of approx. 30—145 km/h {19—90 mph} (Australian, General (L.H.D.) specs.)
―  MRCC system is ON
―  Brake pedal is not depressed
―  Clutch pedal is not depressed (MTX)
―  DSC HU/CM is not operating
―  TCS is not operating
―  Smart city brake support (SCBS) is not operating
―  Smart brake support (SBS) is not operating
―  Parking brake is released

Constant speed control mode

1.  The vehicle control module (V/C-module) recognizes the vehicle speed setting set by the driver based on the cruise control switch operation signal sent from the start stop unit when the operation conditions are met.
2.  The vehicle control module (V/C-module) sends the set vehicle speed signal to the PCM based on the recognized set vehicle speed and sends a system status display request signal to the instrument cluster.
3.  The PCM performs engine control to maintain the set vehicle speed based on the signal from the vehicle control module (V/C-module).
4.  The instrument cluster displays the MRCC system operation screen based on the signal from the vehicle control module (V/C-module).
Note
•  If for some reason, the vehicle speed decreases to 25 km/h {16 mph} or less while in constant speed control mode, the vehicle control module (V/C-module) cancels constant speed control mode and switches to standby status.
•  When the vehicle control module (V/C-module) receives the target information signal from the radar sensor while in constant speed control mode, it switches the mode to headway control mode.
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Headway control mode

1.  When the vehicle control module (V/C-module) receives the target information signal from the radar sensor while in constant speed control mode, it switches the mode to headway control mode.
2.  The vehicle control module (V/C-module) calculates the target acceleration speed based on the following, and sends the target acceleration speed signal to the PCM and DSC HU/CM. Additionally, it sends the system status display request signal to the instrument cluster.
―  Distance between vehicles set by driver
―  Target information signal from radar sensor (position of vehicle ahead, distance between detecting vehicle and vehicle ahead, relative speed)
―  Detecting vehicle speed
3.  The PCM performs engine control to maintain distance between vehicles based on the signal from the vehicle control module (V/C-module).
4.  The DSC HU/CM controls the brakes to maintain distance between vehicles based on the signal from the vehicle control module (V/C-module).
5.  The instrument cluster displays the vehicle ahead display based on the signal from the vehicle control module (V/C-module).
Note
•  In the following cases, the system transitions from headway control mode to constant speed mode.
―  Vehicle ahead accelerates over set vehicle speed of detecting vehicle
―  Vehicle ahead or detecting vehicle switches driving lanes and vehicle ahead of detecting vehicle no longer exists
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Distance between vehicles setting
•  Using the DISTANCE switch on the cruise control switch, the distance between vehicles can be controlled at 4 levels, including long→medium→short→extremely short (initial setting is set to LONG).
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Distance between vehicles table (reference)

Set distance between vehicles

Detecting vehicle speed

30 km/h {19 mph}

40 km/h {25 mph}

50 km/h {31 mph}

60 km/h {37 mph}

70 km/h {43 mph}

80 km/h {50 mph}

90 km/h {56 mph}

100 km/h {62 mph}

110 km/h {68 mph}
Long
23 m
{75 ft}
29 m
{95 ft}
36 m
{118 ft}
42 m
{138 ft}
48 m
{157 ft}
55 m
{180 ft}
61 m
{200 ft}
67 m
{220 ft}
74 m
{243 ft}
Medium
19 m
{62 ft}
24 m
{79 ft}
29 m
{95 ft}
34 m
{112 ft}
39 m
{128 ft}
44 m
{144 ft}
49 m
{161 ft}
53 m
{174 ft}
58 m
{190 ft}
Short
15 m
{49 ft}
18 m
{59 ft}
22 m
{72 ft}
25 m
{82 ft}
29 m
{95 ft}
32 m
{105 ft}
36 m
{118 ft}
40 m
{131 ft}
43 m
{141 ft}
Extremely short
12 m
{39 ft}
14 m
{46 ft}
17 m
{56 ft}
20 m
{66 ft}
22 m
{72 ft}
25 m
{82 ft}
27 m
{89 ft}
30 m
{98 ft}
32 m
{105 ft}

Set distance between vehicles

Detecting vehicle speed

120 km/h {75 mph}

130 km/h {81 mph}

140 km/h {87 mph}

150 km/h {93 mph}

160 km/h {99 mph}

170 km/h {106 mph}

180 km/h {112 mph}

190 km/h {118 mph}

200 km/h {124 mph}
Long
80 m
{262 ft}
86 m
{282 ft}
93 m
{305 ft}
99 m
{325 ft}
105 m
{344 ft}
105 m
{344 ft}
105 m
{344 ft}
105 m
{344 ft}
105 m
{344 ft}
Medium
63 m
{207 ft}
68 m
{223 ft}
73 m
{240 ft}
78 m
{256 ft}
83 m
{272 ft}
88 m
{289 ft}
90 m
{295 ft}
90 m
{295 ft}
90 m
{295 ft}
Short
47 m
{154 ft}
50 m
{164 ft}
54 m
{177 ft}
57 m
{187 ft}
61 m
{200 ft}
64 m
{210 ft}
68 m
{223 ft}
72 m
{236 ft}
75 m
{246 ft}
Extremely short
35 m
{115 ft}
38 m
{125 ft}
40 m
{131 ft}
43 m
{141 ft}
45 m
{148 ft}
48 m
{157 ft}
51 m
{167 ft}
53 m
{174 ft}
56 m
{184 ft}

Caution
•  The distances between vehicles indicated above are average values during travel on flat roads and differ depending on the driving and road conditions.


Inter-vehicle distance limit warning

•  If any of the following conditions is met, the warning alarm in the instrument cluster is activated and the brake warning in the display is indicated to urge the driver to apply the brakes.
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―  vehicle control module (V/C-module) determines that crash is unavoidable even if automatic braking is performed at maximum possible deceleration rate
―  Vehicle ahead performs emergency braking


Shift up/shift down request (MTX)

•  If the transaxle gear position is not appropriate to the vehicle speed while the MRCC system is operating, a shift up/shift down request is displayed in the active driving display of the instrument cluster.
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Caution
•  If the vehicle continues to be driven without following the shift up request, the continuous high engine speed will apply a load on the engine which could cause engine damage. Shift the gears up in accordance with the shift up request.
•  If the vehicle continues to be driven without following the shift down request, it could cause the engine to stall. Shift the gears down in accordance with the shift down request.
•  If the vehicle continues to be driven without following the shift up/shift down request, the vehicle control module (V/C-module) will automatically cancel the MRCC system to reduce the load on the engine.
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Note
•  When driving on a steep downhill, a shift down request may be indicated to decrease the load on the brakes required to maintain a constant vehicle speed.