LUCAS ACE - System Overview

The Active Corner Enhancement system manufactured by Rover Group Lucas appears to have been produced specifically for the Land Rover Discovery series II to address the poor cornering association of the Discovery series one. Constantly monitoring very sensitive G sensors mounted at high and low points on the vehicle, the system can detect roll forces and counter them using the output of a hydraulic pump via valves and powerful actuators mounted on both axles to resist the roll forces thus reducing cornering roll. The system is a vast improvement to the vehicles handling allowing much sharper cornering than without, and anyone used to driving with is needs to be careful should it stop working, or due to the fact that it was an optional extra, they lend a non ACE equipped vehicle, not to forget to slow down more than usual at corners. The system has very fast response requirements and as such there is much emphasis on ensuring that the system works properly and fast enough. New ECU’s have to pass a number of response tests successfully before the system is commissioned to try and ensure this. There is also sensor calibration and sophisticated bleeding procedures. Interestingly or amusingly, the ECU is housed in an identical case to the MEMS 1.9 engine management with a blanking plug fitted where the vacuum tube inlet is, no doubt a cost saving measure.

SM032 - LUCAS ACE - System Help file

Version 1.27

LUCAS ACE - Known Fitments

Vehicle makes, models and variants known or believed to be using this vehicle system, required diagnostic lead and degree of known compatibility. Vehicle Make Vehicle Model Vehicle Variant Diagnostic Lead Land Rover Discovery II When Fitted Black OBDII Lead

LUCAS ACE - Physical Details

LUCAS ACE - Pin Outs

Details of the pin usage for the ECU connector(s).   1 -4 Not used 5 Road speed - input 6 ACE relay 7 - 9 Not used 10 Diagnostic line 11 Ignition on - input 12 Lower lateral accelerometer power supply 13 Not used 14 Reverse switch 15 Lower lateral accelerometer - input 16 Pressure transducer - input 17 Upper lateral accelerometer - input 18 Upper lateral accelerometer power supply 19 Engine speed - input 20 Ground 21 Pressure transducer ground 22 Direction control valve 2 - input 23 Direction control valve 1 - input 24 Power supply for DCV 1 and 2 25 Pressure control valve input 26 Not used 27 Power supply for PCV 28 Main supply 29 - 31 Not used 32 Ground 33 Lower lateral accelerometer ground 34 Upper lateral accelerometer ground 35 Not used 36 Warning lamp

SM032 - LUCAS ACE - Diagnostic Capabilities (Read Fault Codes)

Reads the fault code memory. The system can self detect up to 45 different problems with itself and associated sensors, storing the respective code if it detects any malfunction or reading outside of pre defined acceptable limits. Not all stored faults may cause the fault warning lamp to illuminate. Some faults, even if stored in the ECU memory, are masked and therefore the Test Book is not showing them. We decided to show all faults stored in the ECU. The masked faults are preceded by "MASKED FAULT" text.

SM032 - LUCAS ACE - Diagnostic Capabilities (Clear Fault Codes)

Clears the fault code memory.

SM032 - LUCAS ACE - Diagnostic Capabilities (Settings)

Values, configuration settings and other stored information which can be read from the ECU, edited and then rewritten back. Read settings can also be stored as a standard HTML page for reference. These pages can then later be re loaded and re written back to the ECU. Please note that some values may be read only due to the fact that they are supplied from the ECU’s ROM or are internally calculated. Vehicle type: This identifies the vehicle type for which this ACE ECU is configured. ECU ID: This is the ECU ID number which specifies its build revision. Tune reference: This gives the number by which different market or vehicle model or specification tunes can be identified. New/Used: This identifies if the ECU is new (Virgin State) or used. Before a new ECU can be used the main relay has to be energized, then have the lateral accelerometers calibrated, which can be done using the 'SELF CALIBRATE' function found in 'OTHER' section. It also must pass all 5 'RESPONSE TIME' tests also found in the 'OTHER' section. Until these functions are performed, the ECU as an internal feature will not function correctly and will keep the fault lamp illuminated. Once this has been done this value will change from saying 'NEW to say 'USED' and the ECU will function properly. At the end of the tests, return the main relay to normal.

SM032 - LUCAS ACE - Diagnostic Capabilities (Inputs)

A constantly updating display in HTML of real time information the electronic control unit of the selected vehicle system is currently deriving from its input sensors and switches. These displays can be saved as HTML snap shots, recorded as an AVI movie or captured as A CSV data file for import into a spread sheet program such as Excel. Actual pressure: This is the pressure in bars derived from the pressure transducer which is mounted on the front face of the hydraulic valve block on the right hand chassis rail. Residual pressure: It may be noticed that when the PCV is closed i.e. drawing no current, that the actual pressure reading is not zero Bar. This pressure offset is known as the residual pressure and it is critical to the 'on centre' feel of the vehicle and initial roll when cornering. Ideally the residual pressure should be zero; however in practice it can vary between typically 3Bar and 6Bar. These variations are caused by component tolerance, valve design and temperature effects on the viscosity of the oil. The higher the residual pressure, the larger the dead-band around centre or straight line driving. If the system requests pressure less than the residual pressure the system is switched into the 'locked bars' state. Residual pressure is measured by the ACE ECU every 12 seconds when the direction valves are closed and there is no lateral acceleration and the engine speed is above 550rpm. The residual pressure value should drop nearly 50% within the first 2 minutes of starting the engine from cold. As the ambient temperatures decrease, the initial value of residual pressure will increase. Compensated pressure: This is an internally calculated value is used to filter pressure sensor outputs for the pressure controller and determines residual pressure and pressure sensor offset. Residual pressure is measured every 12 seconds when the direction valves are closed and there is no lateral acceleration and the engine speed is above 550rpm. Road speed: Used in roll compensation and off-road algorithms, which is vehicle speed dependent. Battery volts: This is the current battery voltage which supplies the ACE ECU. RPM: A pulse train generated by either the Bosch Engine management or the TD5 engine management ECU's. Main relay: This is the current status of the ACE systems main relay, this is controlled by the ACE ECU and can be tested with an output function provided in the 'OUTPUTS' section. When an ACE ECU is new as shown in the settings section, the ACE ECU will not energies this relay until the ECU has passed all response tests and been self calibrated, however to do this the system needs the power provided by this relay. Warning lamp: This shows the current status of the ACE systems warning lamp, which is located in the instrument pack. Ignition: Used to wake up the ACE ECU and provide shutdown signal at power off. The ECU stays powered up for 30 seconds after ignition is turned off. Reverse: Used to change the ACE system functionality. This is supplied via switch S210 in an automatic vehicle or switch S103 in a manual vehicle. Upper lateral accelerometer/gravities: A capacitive acceleration sensor located on a bracket in the roof lining above the rear view mirror. It is driven by a 5.0Vdc supply from the ACE ECU on pin 18 of C0647 on a yellow / red wire. The buffered output is 0.25 -4.75Vdc which returns to the ACE ECU on pin 17 of C0647 on an orange / blue wire. The sensor can measure ± 1.14g. It is fed with earth from pin 34 of C0647 on a yellow / green wire. Its input is used for 'head toss' correction and fault detection in conjunction with the lower accelerometer. With the vehicle on level ground with all the doors closed, both accelerometers should read ± 0.01g after calibration: After normal usage, the difference between the upper and lower accelerometers could be as much as ± 0.15g. Lower lateral accelerometer/gravities: A capacitive acceleration sensor located on a bracket attached to inner sill panel under RH front floor. It is driven by a 5.0Vdc supply from the ACE ECU on pin 12 of C0647 on a yellow / black wire. The buffered output is 0.25 -4.75Vdc which returns to the ACE ECU on pin 15 of C0647 on an orange / grey wire. The sensor can measure ± 1.14g. It is fed with earth from pin 34 of C0647 on a yellow / green wire. While two independent accelerometers are used, this is the primary sensor used to measure acceleration on the vehicle. The sensor's outputs are fed to separate A/D inputs of the ACE ECU's main microprocessor. With the vehicle on level ground with all the doors closed, both accelerometers should read ± 0.01g after calibration: After normal usage, the difference between the upper and lower accelerometers could be as much as ± 0.15g. Directional control valve 1/amps: The ACE ECU controls the DCV's by varying a 200 Hz pulse width modulated signal supplied to it. The higher the mark space ratio of this signal gets the more current is consumed by the DCV's. This value therefore shows how much the valve is being opened by. Directional control valve 2/amps: The ACE ECU controls the DCV's by varying a 200hz pulse width modulated signal, the higher the mark space ratio of this signal gets the more current is consumed by the DCV's. This value therefore shows how much the valve is being opened by. Pressure control valve/amps: The ACE ECU controls the Pressure Control Valve by varying a 200 Hz pulse width modulated signal which is supplied to it. The higher the mark space ratio of this signal gets the more current is consumed by the PCV. This value therefore shows how much the valve is being opened by.

SM032 - LUCAS ACE - Diagnostic Capabilities (Outputs)

Choice of outputs that can be tested. The outputs would be pulsed. Fault warning lamp: This function flashes the Active Cornering Enhancement Systems warning lamp, which is located in the instrument pack. This confirms that it is under the proper control of the ACE ECU. Direction control valve 1: This function activates Direction Control valve 1, which in conjunction with Direction Control Valve 2, affects the direction torque which is applied to the vehicle to counter cornering forces. With either DCV1 or DCV2 on, which is the default state, the anti roll bars are locked which makes the vehicle suspension stiff. With only DCV1 on, the torque is applied to lean the vehicle to the right and with only DCV2 on, the vehicle leans to the left. If both DCV1 and DCV2 are on, the Anti Roll bars become floppy and soft allowing the vehicle to roll freely. The output can be tested only with the engine running. WARNING: The vehicle may suddenly jerk violently from side to side during this test and so it is vitally important to ensure sufficient clear space around the vehicle. Direction control valve 2: This function activates Direction Control valve 2, which in conjunction with Direction Control Valve 1, affects the direction torque which is applied to the vehicle to counter cornering forces. (See details in DCV1). The output can be tested only with the engine running. WARNING: The vehicle may suddenly jerk violently from side to side during this test and so it is vitally important to ensure sufficient clear space around the vehicle. Direction control valve 1 and 2: This function activates both Direction Control valves 1 and 2. With neither DCV1 nor DCV2 on, which is the default state, the anti roll bars are locked which makes the vehicle suspension stiff. With only DCV1 on, the torque is applied to lean the vehicle to the right and with only DCV2 on the vehicle leans to the left. If both DCV1 and DCV2 are on, the Anti Roll bars become floppy and soft allowing the vehicle to roll freely. The output can be tested only with the engine running. WARNING: The vehicle may suddenly jerk violently from side to side during this test and so it is vitally important to ensure sufficient clear space around the vehicle.

SM032 - LUCAS ACE - Diagnostic Capabilities (Other)

Choice of functions that can be performed. Hydraulic circuit bleeding: During ACE system maintenance or repair, hydraulic fluid may be lost from the system and air introduced. If air is present in the primary circuit (pump, attenuator and PCV) the system will self bleed shortly after starting the engine. The unwanted air will escape when it reaches the reservoir. When air is in the secondary circuit (actuators and associated pipe work) it is necessary to perform the System Bleed procedure using this function. Both actuators are designed to allow oil and air to flow freely through them when the piston is in the fully extended position. In this position, the air will be forced out and allowed to escape to the reservoir. Using the following procedure, it is possible to bleed the front and then the rear secondary circuits with the front secondary circuit being bled first, but it is critically important that both the front and rear actuators are bled independently. The vehicle should be parked on a good solid 4 post ramp with the handbrake firmly on and in park or neutral. Ensure that the fluid reservoir is kept topped up to the maximum and that the pump is primed (details of how to verify this and perform it can be found in the vehicle's workshop manual). Having ensured that the engine is not running, raise the vehicle on the 4 post ramp to normal underside working height. Disconnect both stabiliser links on the front axle only. Do not disconnect the stabiliser links on the front and rear axles at the same time. Free the nut that holds the silent block at the end of the roll bar. Push the stabiliser link on the torsion bar end up and pull the stabiliser link on the actuator side down simultaneously to fully extend the actuator; make sure that no pipes or hoses become stretched or caught. For added safety, lower the vehicle to ground height. Start the engine and whilst it is running, perform the 'Hydraulic Circuit Bleeding' function. WARNING: The vehicle may suddenly jerk violently from side to side during this test and so it is vitally important to ensure sufficient clear space around the vehicle. The 'Hydraulic Circuit Bleeding' function will take around 10 minutes during which you should ensure that the fluid reservoir is kept topped up. When the 'Hydraulic Circuit Bleeding Function' has ended, turn off the engine. Raise the vehicle on the 4 post ramp again and reconnect the front axle stabiliser links. Disconnect both stabiliser links on the rear axle only. Do not disconnect the stabiliser links on the front and rear axles at the same time. For added safety, lower the vehicle to ground height again. Start the engine and whilst it is running perform the 'Hydraulic Circuit Bleeding' function. WARNING: The vehicle may suddenly jerk violently from side to side during this test and so it is vitally important to ensure sufficient clear space around the vehicle. The 'Hydraulic Circuit Bleeding' function will take around 10 minutes during which you should ensure that the fluid reservoir is kept topped up. When the 'Hydraulic Circuit Bleeding Function' has ended, turn off the engine. Raise the vehicle on the 4 post ramp again and reconnect the rear axle stabiliser links. Lower the vehicle to ground height and re check the fluid reservoir level. Run all response time tests found in the 'OTHER' section and confirm that they all pass. Direction control valve 1 (DCV1) off time: This measures 2 system responses, the first being the time it takes for the systems hydraulic pressure to start rising after Direction Control Valve 1 is closed with the Pressure Control Valve set to give maximum pressure and very importantly the engine being kept at above 1300 RPM to allow the pump sufficient power to deliver the pressure required for the duration of the test. Direction Control Valve 2 stays open during this test. The second measured response is the time taken for the rising hydraulic pressure to reach the upper pressure threshold level as previously calculated by the ACE ECU. The first response time should be between 15 and 60 milliseconds and the second response time measured should be between 100 and 250 milliseconds. A failure to pass either of these tests indicates a problem within the ACE system which can be physical such as low fluid, slipping drive belt, worn or otherwise inefficient pump or associated pump drive problems, broken linkages or mountings to the actuators, damaged pipes or faulty valves or actuators, or it could be an electrical fault such as broken wiring or damaged solenoids or other ACE system components. It can also indicate that either the primary or secondary hydraulic circuits need bleeding, functions for this are provided in the 'OTHER' section. WARNING: The vehicle may suddenly jerk violently from side to side during this test and so it is vitally important to ensure sufficient clear space around the vehicle and that it is on good solid and level ground. If someone is sitting inside the vehicle to help with the engine revs required for this test, please ensure that they are adequately informed and braced. Direction control valve 1 (DCV1) on time: This measures the time it takes for the systems hydraulic pressure to start dropping after Direction Control Valve 1 is opened with the Pressure Control Valve set to give maximum pressure and very importantly the engine being kept at above 1300 RPM to allow the pump sufficient power to deliver the pressure required for the duration of the test. The time measured should be between 15 to 60 milliseconds. A failure to pass this test indicates a problem within the ACE system which can be physical such as low fluid, slipping drive belt, worn or otherwise inefficient pump or associated pump drive problems, broken linkages or mountings to the actuators, damaged pipes or faulty valves or actuators, or it could be an electrical fault such as broken wiring or damaged solenoids or other ACE system components. It can also indicate that either the primary or secondary hydraulic circuits need bleeding, functions for this are provided in the 'OTHER' section. WARNING: The vehicle may suddenly jerk violently from side to side during this test and so it is vitally important to ensure sufficient clear space around the vehicle and that it is on good solid and level ground. If someone is sitting inside the vehicle to help with the engine revs required for this test, please ensure that they are adequately informed and braced. Direction control valve 2 (DCV2) off time: This measures 2 system responses, the first being the time it takes for the systems hydraulic pressure to start rising after Direction Control Valve 2 is closed with the Pressure Control Valve set to give maximum pressure and very importantly the engine being kept at above 1300 RPM to allow the pump sufficient power to deliver the pressure required for the duration of the test. Direction Control Valve 1 stays open during this test. The second measured response is the time taken for the rising hydraulic pressure to reach the upper pressure threshold level as previously calculated by the ACE ECU. The first response time should be between 15 and 60 milliseconds and the second response time measured should be between 100 and 250 milliseconds. A failure to pass either of these tests indicates a problem within the ACE system which can be physical such as low fluid, slipping drive belt, worn or otherwise inefficient pump or associated pump drive problems, broken linkages or mountings to the actuators, damaged pipes or faulty valves or actuators, or it could be an electrical fault such as broken wiring or damaged solenoids or other ACE system components. It can also indicate that either the primary or secondary hydraulic circuits need bleeding, functions for this are provided in the 'OTHER' section. Direction control valve 2 (DCV2) on time: This measures the time it takes for the systems hydraulic pressure to start dropping after Direction Control Valve 2 is opened with the Pressure Control Valve set to give maximum pressure and very importantly the engine being kept at above 1300 RPM to allow the pump sufficient power to deliver the pressure required for the duration of the test. The time measured should be between 15 to 60 milliseconds. A failure to pass this test indicates a problem within the ACE system which can be physical such as low fluid, slipping drive belt, worn or otherwise inefficient pump or associated pump drive problems, broken linkages or mountings to the actuators, damaged pipes or faulty valves or actuators, or it could be an electrical fault such as broken wiring or damaged solenoids or other ACE system components. It can also indicate that either the primary or secondary hydraulic circuits need bleeding, functions for this are provided in the 'OTHER' section. WARNING: The vehicle may suddenly jerk violently from side to side during this test and so it is vitally important to ensure sufficient clear space around the vehicle and that it is on good solid and level ground. If someone is sitting inside the vehicle to help with the engine revs required for this test, please ensure that they are adequately informed and braced. PCV off response time: This measures 2 system responses, the first being the time it takes for the systems hydraulic pressure to start rising after the pressure Control Valve is set to give maximum pressure with both of the Direction Pressure Control Valves closed and, very importantly, the engine being kept at above 1300 RPM to allow the pump sufficient power to deliver the pressure required for the duration of the test. Direction Control Valve 2 stays open during this test. The second measured response is the time taken for the rising hydraulic pressure to reach the upper pressure threshold level as previously calculated by the ACE ECU. The first response time should be between 4 and 50 milliseconds and the second response time measured should be between 0 and 90 milliseconds. A failure to pass either of these tests indicates a problem within the ACE system which can be physical such as low fluid, slipping drive belt, worn or otherwise inefficient pump or associated pump drive problems, broken linkages or mountings to the actuators, damaged pipes or faulty valves or actuators, or it could be an electrical fault such as broken wiring or damaged solenoids or other ACE system components. It can also indicate that either the primary or secondary hydraulic circuits need bleeding, functions for this are provided in the 'OTHER' section. WARNING: The vehicle may suddenly jerk violently from side to side during this test and so it is vitally important to ensure sufficient clear space around the vehicle and that it is on good solid and level ground. If someone is sitting inside the vehicle to help with the engine revs required for this test, please ensure that they are adequately informed and braced. ECU self calibration: Both the upper and lower accelerometers are subject to alignment and offset errors in their zero 'g' position. Before the ACE system can operate correctly the sensor positions must be stored in the ECU. The stored values are used as the initial offset in the accelerometer zero tracking algorithm. If the offset is not corrected the vehicle may have a permanent lean or generate an error depending on the value. The ACE ECU will remove small errors in the offsets during normal driving. However to calibrate the accelerometers at any time, especially when a new ECU is fitted, use this function. Energise main relay: This function keeps the main relay energised and it should be run on a new ECU before ECU self calibration and valve tests. Return relay to normal: This function returns the main relay function to normal.