DI­AG­NOS­TIC TOOLS

Car (South Africa) - - TECH -

I have seen the Uber x MD+ di­ag­nos­tic tool ad­ver­tised (pic­tured). Can you con rm how this sys­tem ac­tu­ally works to di­ag­nose pow­er­train-re­lated is­sues of ve­hi­cles? JENS KERNECK Klerks­dorp

Nat­u­rally, we can eval­u­ate prod­ucts only once we have phys­i­cally tested them. From the pic­ture, it is clear that this is one of the generic OBD scan tools that con­nects to a ve­hi­cle’s on­board di­ag­nos­tic port. It usu­ally com­mu­ni­cates to another de­vice (like a smart­phone or tablet) via Blue­tooth.

The OBDII was in­tro­duced in the US dur­ing the 1990s and the equiv­a­lent EOBD stan­dard in Europe only in 2001. The stan­dard de nes the com­mu­ni­ca­tion pro­to­col used by a ve­hi­cle’s elec­tronic con­trol mod­ule (es­pe­cially the ECU) for di­ag­nos­tic in­for­ma­tion. When the ECU de­tects a prob­lem with a sen­sor, ac­tu­a­tor or sys­tem, it stores a di­ag­nos­tic trou­ble code (DTC) in its mem­ory and, de­pend­ing on the fault, may il­lu­mi­nate a warn­ing light (mal­func­tion-in­di­ca­tor lamp).

Many DTC are leg­is­lated (es­pe­cially the emis­sion-re­lated faults) and they must there­fore be vis­i­ble to a generic scan tool. There are other faults that are man­u­fac­tur­erspeci c and are not vis­i­ble to such a tool, but only to the man­u­fac­turer’s ser­vice sys­tems. A mod­ern ve­hi­cle can eas­ily have more than 500 fault paths (with DTC) in the pow­er­train sys­tem alone.

The scan tools should also pro­vide re­al­time data such as en­gine speed, ve­hi­cle speed and man­i­fold pres­sure, to name a few. These chan­nels are again reg­u­lated by the OBD stan­dard and may be use­ful for fault di­ag­no­sis or even the record­ing of ve­hi­cle data for eet pur­poses.

A mod­ern ve­hi­cle has many ECUS, all con­nected on a sin­gle net­work called the CAN bus. The OBD con­nec­tor con­nects to the CAN bus and serves as a port to con­nect to many mod­ules, in­clud­ing trans­mis­sion, in­stru­ment clus­ter and even the ABS unit in some cases.

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