Car Mechanics (UK) - - Diagnostics Masterclass -


◀ The VCA is in­serted into the EOBD socket. This pro­fes­sional tool works wire­lessly, via Blue­tooth, where in­for­ma­tion is passed to and from the di­ag­nos­tic hard­ware.


▶ Bat­tery volt­age must not be al­lowed to drop be­low a cer­tain level, which varies be­tween dif­fer­ent car mod­els. An ex­tra power sup­ply must be pro­vided to avoid the risk of cor­rupt­ing the ECUS.


Hand­held tools with in­te­gral screens are pop­u­lar for both pro­fes­sion­als and Diy­ers but, for greater clar­ity, we have used the larger touch­screen from Hella Gut­mann So­lu­tions’ mega macs 77 model.


While you can en­ter the ve­hi­cle’s ID by make and model, a far more ac­cu­rate method is to have the di­ag­nos­tic tool recog­nise the car by its VIN num­ber. For this, the ig­ni­tion must be switched on.


In this case, the reg­is­tra­tion num­ber and mileage are en­tered. This is so the cal­i­bra­tion re­sults are shown on a print­out – ask a garage to pro­vide this in­for­ma­tion post-cal­i­bra­tion.


◀ A full global scan will re­veal which ECUS are present on the ve­hi­cle, by in­ter­ro­gat­ing them for any er­rors – this may be the first time you dis­cover its full spec­i­fi­ca­tion.


▶ This read­out shows ‘(!)’ for ECUS pos­sess­ing a fault code, ‘0’ if an ECU is recog­nised but there are no faults, and ‘---’ if an ECU is not present. This car, there­fore, is not fit­ted with a rear cam­era, or main beam as­sist.


◀ Any er­rors within an ECU are logged as fault codes. At this stage, the di­ag­nos­tic tool in­ter­ro­gates each ECU in more de­tail and lists how many fault codes have been recorded.


◥ If you are work­ing on some­one else’s car, let them know if other fault codes are found, so you are not blamed for caus­ing them. Here, we are in­ter­ested in the ADAS dis­tance con­trol fault.


◀ This pro­fes­sional ma­chine shows not only the fault code but also gives an ex­pla­na­tion. Ba­si­cally, this is a Can­bus er­ror, which may be caused by a cal­i­bra­tion con­flict.


▴ The fault code is deleted. As it clears and does not come back, it seems as though this is a tem­po­rary fault, but a cal­i­bra­tion should still be car­ried out to elim­i­nate align­ment as a fac­tor.


▴ On this di­ag­nos­tic ma­chine, front cam­era cal­i­bra­tion is ac­cessed via a ba­sic set­tings menu, then a cam­era cal­i­bra­tion menu. Three dif­fer­ent cam­era op­tions can be se­lected for this Volk­swa­gen.


◀ About 99% of the time taken to con­duct a static cam­era cal­i­bra­tion is in­volved with set-up. As this list is fairly el­e­men­tary, we will fo­cus on the last five items that in­volve the cam­era and sen­sor cal­i­bra­tion (CSC) tool.


▴ The front cam­era is lo­cated be­hind the wind­screen on this car (ar­rowed), but it can carry out more than one func­tion de­pend­ing not only on make and model, but also in­di­vid­ual car spec­i­fi­ca­tion.


▴ The front cam­era is cal­i­brated us­ing a CSC tool to which is fit­ted a non-re­flec­tive cal­i­bra­tion board con­tain­ing mark­ings be­spoke to each make/model, which must be po­si­tioned ac­cu­rately (see Step 17).


▴ While it is not be­ing cal­i­brated here, radar sen­sors that con­trol func­tions such as auto-brake and dis­tance cruise con­trol need cal­i­brat­ing sep­a­rately with a dif­fer­ent metal re­flec­tive plate.


◀ Things get more com­pli­cated on newer cars with side-mounted cam­eras for all-round­vi­sion. Older cars with front cam­eras and radar sys­tems have dif­fer­ent cal­i­bra­tion boards that are num­bered.


▶ The dis­tance be­tween the cen­tre of both front wheel hubs and the CSC tool is mea­sured us­ing a wheel mount (which is fit­ted and lev­elled) and a laser mea­sur­ing de­vice mounted to the CSC tool (see in­set pic).


◀ Wheel mounts are re­moved from the fronts and fit­ted to both rear wheels. They must also be lev­elled. This ex­er­cise is to check that the rear axle and the CSC tool are par­al­lel.


▶ Each mount’s laser beam (which trav­els in a straight line) is ac­ti­vated. The light is re­flected into the CSC mir­ror and back onto the grad­u­ated scale. How­ever…


◀ …while the read­ings them­selves are of no rel­e­vance, the off­side and near­side read­ings must be the same or within one digit of tol­er­ance.


▶ If the read­ings are not the same, the op­er­a­tor must move the CSC tool care­fully, un­til they match.


◀Fi­nally, the board is lev­elled and its height must be set to the car-maker’s spec­i­fi­ca­tion, men­tioned on the di­ag­nos­tic tool (see Step 13). The CSC tool has a grad­u­ated scale for this.


▶ Fi­nally, the car’s ride height is ver­i­fied again us­ing a laser mea­sur­ing tool that takes a fig­ure from the cen­tre of the whee­larch to the floor – this ac­counts for sag­ging sus­pen­sion springs.


◀As the ride height is so im­por­tant (note that some cars re­quire a full tank of fuel), the fig­ures are en­tered into the di­ag­nos­tic equip­ment, which in­flu­ences the cal­i­bra­tion.


▶ Once se­lected, the cal­i­bra­tion takes place within sec­onds. Here, the cam­era spec­i­fi­ca­tions are pro­vided with the con­fir­ma­tion that the ex­er­cise has been com­pleted suc­cess­fully.


◀When prompted, the ig­ni­tion must be switched off and on again. It is wise to open a win­dow and reach through rather than to open the door, which can move the car and af­fect cer­tain ECUS.


▶ A full global scan is per­formed again to check that the work has not af­fected any other ECUS. Here, it is noted that the radar dis­tance con­trol sen­sor has recorded a new fault code.


▴ Closer in­ter­ro­ga­tion shows that the radar sen­sor lost com­mu­ni­ca­tion with the cam­era as it was be­ing cal­i­brated. This is nor­mal, be­cause the cam­era goes off­line dur­ing the pro­ce­dure.


◀ As the fault code was cleared suc­cess­fully and did not re­turn, the ig­ni­tion sys­tem was switched off and the VCI dis­con­nected from the EOBD port.


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