Impreza Sensors Manual Page

 



[Wheel Sensor] [Gearbox Sensor] [Speedo Sensor] [Trouble Shooting] [Pre-Scaler Interface]

Before fitting any type of sensor to a vehicle

Connect it up to the Brantz meter and check its' correct operation by rotating the inner of speedometer cable types, or repeated touching of wheel types to a metal object. Use a low calibration figure on the meter, and watch the readouts increment. If the readouts do not increment there is a problem which should be investigated. Make absolutely sure that sensors are correctly connected before turning on the meter as they will be destroyed by reverse current.

 

Wheel Sensor Installation

Before fitting the sensor to the vehicle, connect it up to the tripmeter and test its' functionality by touching the sensing end many times with a screwdriver, and note that the tripmeter increments. A bracket to mount the sensor to the suspension strut should be made rigid enough to prevent flexing. Bolt heads (a minimum of four for accuracy) should pass squarely across the face of the sensor all at a distance of 1mm (IMPORTANT). Socket head bolts cannot be used as they cause problems. Correct fitting of the sensor can be checked by monitoring the voltage across the sensor with a voltmeter. When connected to the tripmeter and the sensor is next to a bolthead the voltage should be about 2 volts. When the sensor is clear of the bolt head the voltage should be about 4.2 volts. Check that all (four?) bolts give similar results. If the tripmeter is put onto calibration figure 0001 then all four bolts should cause the tripmeter to increment.

 

Wheel Sensor Installation

 

Gearbox (Japanese/Ford)

Most Japanese manufacturers have standardised their gearbox outputs to accept a M22 x 1.5 threaded sensor which has a round peg drive with a 'lug' pinched onto the side. Unscrew the original speedometer cable from the gearbox, screw in the Brantz Jap sensor with the drive pin in place, and screw the original speedometer cable into the sensor. Wiring is to the Brantz GREY cable as follows: Green to Green, Blue to Blue, Brown to Brown. Some Jap sensors have a different colour code and are wired as follows: Green to Black or Silver, Brown to Red, Blue to White. Many Ford/GMfVauxhall FiatIVW/Skoda/Lada gearbox outputs are similar in that they have a square drive and a Ml8 x 1.5 screw thread. The Brantz Ford/GM sensor will fit many of these vehicles but will require some degree of filing/cutting/drilling before they are an acceptable engineering fit. Select this sensor only if you have the skills to do this. Wiring is the same as for the Jap sensor above.

 

Japanese Gearbox

Japanese Gearbox Sensor

 

Ford/GM Gearbox Sensor

Ford GM Gearbox Sensor

 

Universal Speedometer Cable

This plastic unit fits in the length of almost any speedometer cable, though some old cables require holes to be slightly enlarged due to 'chunky' cable dimensions, and some modern speedometer cables need ingenuity to dismantle them as manufacturers seem to want to prevent customers from separating the inner from the outer. Generally with the so-called 'sealed' cables, a section of sheath from the centre of the cable should be removed first to obviate the fixing system used on the ends of the inner. Replacement lengths of sheath can always be put back in after the cable has been separated. Heat-shrink sleeve, particularly the type which is adhesive-lined makes easy repairs to segmented sheaths. To assist with fitting, a cross-section of the universal sensor is shown. Note that the rotor floats in air and puts no additional strain on the speedometer drive, but this construction demands that the sensor should not be subjected to 'end thrust' which could be produced by a worn cable, or being fitted on a bend in the cable. Modern sensors can be stripped to help with fitting in difficult cases. Connections are Brown to Brown, Blue to Blue; Green to Green.

 

Universal speedometer cable installation

Universal Speed Cable Sensor

Speedometer cable installation

 

Directions

1. Remove inner core. Cut through the outer sheath at the location of the sensor with a fine toothed hacksaw. 32 teeth/inch recommended.

2. Make a second cut through sheath to shorten the sheath by 1/2 inch (13mm).

3. Remove any burrs with a fine file.

4. Wipe off any excess grease and any metal debris from the inner and the outer, and re-insert the inner which has an enlarged end through its' section of sheath.

5. Place clamps (Jubilee clips or preferably screw type petrol hose clips) on to both ends of the plastic sensor.

6. Insert the loose end of the speedometers cable inner into one end of the sensor and push very firmly through the sensor's internal friction bushing until the sheath section is fully seated in the sensor. If your speedometer cable sheath is of a smaller diameter than can be easily clamped by the sensor then build up the diameter of the sheath with adhesive aluminium tape. Tighten the clamps moderately.

7. Feed the loose end of the inner through the last piece of sheath until it is fully inside the sensor. Tighten the clamps moderately. If you do not wish to use clamps, they could be replaced with adhesive lined heat-shrink sleeve.

 

Trouble Shooting

If it is suspected that either a wheel or speedometer sensor has been damaged in service (ie tripmeter does not increment on the road) then the output from the sensor can be tested with a voltmeter (voltage varies as wheel or sensor is rotated 2 volts to 4 volts). Alternatively the tripmeter itself can be proven to be OK by the following test which must be carried out strictly in the order described, a) Switch off the meter. b) Pull off the three push-on connectors from the grey cable to the sensor. c) Ease back the insulating sleeves from the Blue and Green wires of the grey cable described in b). Keep these away from contact with anything else. d) Select calibration 001 on the tripmeter. e) Switch on the tripmeter. f) Press all the zeroing buttons. g) Tap the above Blue and Green wire connectors together electrically many times. The tripmeter should increment. If it does, and there is no increment during normal use on the road with the sensor connected, then the sensor has indeed been damaged and the tripmeter itself is still functional. The other type of misoperation from which a tripmeter can suffer is self-stepping whilst the vehicle's engine is running, or self zeroing, or readouts going on and off by themselves. Assuming the power supply is reliable (try powering the meter directly from a separate battery placed temporarily in the passenger area) then suspect powerful radio interference from home-made H.T. sparkplug leads. This is particularly common with historic vehicles. Replace them with standard proprietary parts from an accessory shop. Testing for interference is easily demonstrated using a portable radio on the AM band (important). Tune away from the stations into a quiet frequency, turn up the volume, then start up the engine. Listen for loud clicks. That's interference which should be cured, as it is far too powerful to defend against with screening etc. Vehicles with interference will normally fail pre-event scrutineering.

 

Pre-Scaler Interface

This interface is intended to safely drive Brantz meters from digital pulse supplies found on vehicles fitted with digitally pulsed electronic speedometers or tachographs and as such, substitute for other types of motion sensors. Some types of ABS sensors are suitable as inputs to the interface, though some ABS systems do not generate a speedometer pulse until they reach a certain speed and so are not capable of accurate work Check with your car supplier. The three push-on connectors on the right of the device are colour coded to match the wires inside the GREY cable coming from the Brantz meter. The single push-on connector on the left of the interface will respond to digital ground pulses coming from the vehicle. Confirm suitability with a voltmeter before connecting the interface to the vehicle's pulse wire: Low signal = less than one volt, high signal is greater than 4 volts positive with respect to ground. Analogue sources are not suitable. Check that the signal occurs at very low speeds as well as at normal.


The rotary switch on the interface sets the prescale ratio and should be greater than zero. The lower the prescale ratio is, the greater the meter accuracy will be, but this facility is provided to compensate for very high pulse rates which would take the Brantz meter out of its normal calibration range of up to 999. If the meter calibration is out of range, rotate the prescale ratio above the normal setting of ONE. Prescalers version 6 also have a SENSITIVITY control under the Prescale Switch. This control adjustment should normally be placed about centrally in its' range, but rotated anticlockwise it allows desensitization of the input threshold which could be useful in hostie environments, and in its' clockwise direction, the interface is sensitized to lower voltages which can permit some types of ABS-derived speed pulses to be detected a little more reliably than would otherwise be possible. Technical information: Drain on the vehicle's sensor is less than 0.5mA, TTL Compatible. Interface current consumption is less than lOmA. Input is 'dioded' to prevent interaction of the interface and the vehicle if the meter is switched off. Divide ratio = figure on the rotary switch (1 to 15) zero is not valid. Power source from meter is 5 volts, interface is not protected from reverse connection. Output is open collector.

Hall Effect :
Special sensor for generic detection of rotating shafts to provide distance sensing for the Brantz range of odometers.
This sensor type is a fall-back fitment to be utilised when the more easily implemented standard types are unuseable and requires some level of interpretation for each individual situation. Select this sensor option only if you are able to provide some amount of engineering expertise and originality. The detector section of the standard universal speedometer cable sensor is wired as normal to the Brantz odometer's sensor wires (usually in the grey cable) green to green, blue to blue, brown to brown. BEFORE fitting to the vehicle is attempted, demonstrate the functionality of the components IN THE HAND by wiring to the Brantz odometer (on a low calibration figure) and pass the white end of the magnet across the white dot of the sensor. See the odometer increment. Do not proceed to the fitting stage without this test.

Hall Sensor Diagram

The sensor has a detection spot which has been highlighted with a white dot. The actual package appearance of the sensor may differ from the picture above. The supplied magnet has a painted white dot on one end which must pass the sensor dot at about 5mm distance. The magnet must be attached to the rotating shaft so that the white end is pointing radially out from the shaft. A non-magnetic band (such as aluminium) could be fabricated to wrap around the shaft and magnet, and a holding compound such as sanitary silicone sealant could be used to prevent looseness. Two or more magnets could be used to increase vehicle accuracy. The black sensor should be provided with a mounting bracket which moves around at the same time as the axis of the rotating shaft so that gaps are not varying unduly. If a metal rod is used as a mounting, the rod can be pushed into the tubular section of one of the sensor types and can be clamped in place with a jubilee clip or similar. Check the output on the blue wire with a voltmeter when everything is connected up to show that a voltage change occurs (0volts to 5volts and back etc) as the magnet passes the sensor. Wiring colour codes to the Brantz GREY CABLE for the sensor are: Green to Green (or Green/Yellow), Blue to Blue, Brown to Brown (or to Red). Information regarding the use of Brantz odometers is available on www.brantz.co.uk

 

Wheel Sensor Installation

Before fitting the sensor to the vehicle, connect it up to the tripmeter and test its' functionality by touching the sensing end many times with a screwdriver, and note that the tripmeter increments. A bracket to mount the sensor to the suspension strut should be made rigid enough to prevent flexing. Bolt heads (a minimum of four for accuracy) should pass squarely across the face of the sensor all at a distance of 1mm (IMPORTANT). Socket head bolts cannot be used as they cause problems. Correct fitting of the sensor can be checked by monitoring the voltage across the sensor with a voltmeter. When connected to the tripmeter and the sensor is next to a bolthead the voltage should be about 2 volts. When the sensor is clear of the bolt head the voltage should be about 4.2 volts. Check that all (four?) bolts give similar results. If the tripmeter is put onto calibration figure 0001 then all four bolts should cause the tripmeter to increment.

 

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