By Greg Neuman, CEI senior manager of quality control

Thanks to digital technology, cars and trucks are safer and more fuel efficient than ever, but the growing number of computers installed on them has also made them more difficult, time-consuming and expensive to repair.  What’s more, with all the customer demands for more safety, navigation and information features, the problem is only going to get worse for as long as anyone can see.

Consider this: there’s more computing power on the typical new car or truck than was on board the Apollo 11 spaceship that went to the moon.  The average car has 30 to 50 different computers, and high-end cars have as many as 100, and they’re accompanied by 60 to 100 different electronic sensors.  And it’s not just the hardware that’s ballooned, but the software too.  Apollo 11 had 145,000 lines of computer code, but cars today can have more than 100 million.

What are these computers doing?  Referred to as ECU’s – short for Electronic Control Units – they run most of the functions of your vehicle. The biggest coordinates all the aspects of a car’s engine, including the fuel injection rate to the ignition, throttle, timing, emissions and cooling. Others monitor the anti-lock brakes, traction control, stability control, air bags, the windshield wipers, headlamps, and air conditioning.  Then there are those that run the navigation system, music system, mobile phones, digital dashboard displays and, more recently, the driver assist systems.

The challenge for body repair shops is that when an accident happens, depending on where the damage is, one or more of these can be knocked out of commission, and instead of using wrenches, torches and hammers, repairmen have to be computer technicians as well.  For example, here’s a chart that shows which kind of systems can be affected by damage in different places on a Honda sedan:


Collision Damage Area Driver Assistance System Components Affected

Front Bumper and Grille

Millimeter Wave Radar Unit

Front Camera (w/ Multi-View Camera System)

Windshield Multi-Purpose Camera Unit

Front Passenger Door/Mirror

LaneWatch™ Camera

Right Side Camera

Driver’s Front Door/Mirror Left Side Camera

Rear Bumper

Blind Spot Information System Radar Units

Rear Camera

For many of the systems computers control, a dashboard warning light comes on.  Routine diagnostics now requires shops to connect a computer to diagnose which electronic systems are affected.  The problem can be one of several:  a faulty circuit that sends a false warning signal; a severed wire in the circuit; and either the sensor or the ECU itself is damaged.  Challenge factor number one:  these parts must be replaced – they can never be repaired.

Challenge factor number two: the diagnosis doesn’t always tell you which of the items in the circuit is the ultimate problem. Instead, the report recommends that just one of the items be replaced. So the shop replaces it, and the follow-up diagnosis may indicate another part need replacing or the dashboard light remains lit.  This process can repeat itself several times for each computerized system before the issue is resolved.

Challenge factor number three:  dealers typically don’t stock rarely needed ECUs, and so have to order them from a regional warehouse. In CEI’s experience, delivery typically adds three to five days to the repair. Challenge factor four: dealers don’t accept returns or make refunds for electronic parts; if the new ECU doesn’t fix your vehicle’s problems, you own it.

With most repairs, few if any of these problems arise, but the potential is always there. But sometimes they surface when you least expect it, and the extra expense can be a nasty surprise. Here’s just one example from CEI:

A late-model sedan ran over some highway debris and suffered undercarriage damage.  When the body work was completed, several dashboard warning lights lit up, even though they weren’t lit when the original estimate was done.  The shop was unable to clear the codes and took the vehicle to the dealer for further diagnostic testing, which showed that two air conditioner sensors and an engine cooling sensor needed to be replaced.

The replacements cleared the related engine codes, but the air bag warning light showed, indicating they might not deploy in an accident. The solution turned out to be a replacement for the air bag control unit and one of the seat belt retractors.  The cost of the electronics repairs:  some $2,500 over and above the body repairs.

So fleets, be forewarned:  your future vehicles will be better than today’s, but they going to cost more to obtain, and cost more and take more time to repair.


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