How could your vehicle rat you out?

If you thought your days of looking over your shoulder to see if someone was tattling on you ended in grade school, think again. But this time it’s not the nosy neighbour or the uber-ambitious co-worker you have to worry about, it’s a member of your own family — your vehicle.

The more computers crammed into your ride, the more memory these devices can retain. And while lawyers can argue about who owns that info and who has a right to it, these little circuit boards go on their merry way, compiling data on how we drive and crash our vehicles, and sometimes that data can later “byte” you in the hard drive.

Data recorders are not on every vehicle on the road, and carmakers are reluctant to advertise their presence, but they’re not uncommon. These devices have no control or diagnostic function, but are simply there to record which of your bad driving skills led up to your latest fender-bender. They constantly record vehicle speed, throttle and brake-pedal action, engine load and sometimes steeringwheel position, and in a collision heavy enough to deploy airbags, they freeze that data in their memory.

The data can then be retrieved to verify if you really were going only 55 km/h as you claimed. In most cases, the data from these automotive black boxes is only used in very serious collisions where a fatality has occurred and other evidence wasn’t enough to get a clear picture of what happened.

Engine computers can also find their way off your Christmas card list if you’re a fan of track driving. Say you take your new sports coupe out for some time trials and things get a little too hot — you’ll find out when you try to get a warranty repair done that these units can also freeze data for retrieval by the tech. Engine computers can spill a lot more beans than black boxes.

While these sorts of things happen rather rarely, the amount of warranty money that transmission computers save automakers every year makes them very reliable informants.

Say a new truck owner brings his or her vehicle back in to the dealership with a complaint that it won’t shift out of second gear. This is often referred to as “limp-home” mode, where the transmission computer calculates the gearbox has a problem but can still be driven, just not very fast or through too many gears.

This condition will always set a diagnostic code that a tech can retrieve. In this case the informant computer says a lot by not saying much at all. The code will usually only indicate a transmission-overheat condition with instructions for the tech to check the cooling system for faults. If no faults are found, then the vehicle is reset and returned to the owner with instructions not to tow or load beyond the vehicle’s specs.