May 11

A Brief Look Into Fixing Your Car

Auto Repair, Car Repair, Mechanic


I know that most folks really don’t want to know the technical details of their car repairs: let’s face it, cars are very complex and beyond the understanding of most people. And this is fine, however as a shop owner and technician I think a little bit of insight into what the technician has to do to repair and service your car goes a long way to create a sense of value for you.

With that in mind I’ve included a picture of a wiring diagram from a recent diagnosis on a 2006 Mercedes. The window washer wasn’t working when you push the washer button. No sounds were heard so it was obvious that the pump wasn’t running and the concern was electrical: either the pump was dead or it was not receiving power when it was supposed to.

This wiring diagram shows the complete wiper and washer system and what is amazing to note is, in addition to the numerous wires, there are 6 computers involved with this system! Now before we get too overwhelmed by that complexity (because as technicians we could…) we need to develop a diagnostic strategy. Fortunately in this case the best place to start and not involve all the complex electronics is at the washer pump itself: we access the pump and test the wiring to the pump. While doing this we found that power and ground was good which confirmed that all other items in the circuit, including those 6 computers were good and the pump was bad.

Fixing Car Washer Pump
Wiring diagram: Note the computers which are circled in red. The washer pump is on the bottom left of the diagram

Diagnosing this concern was quite simple but at some time one of these computers may malfunction and diagnosis will be far more complex and expensive.

Now before you get all smug and say “I don’t have a Mercedes, I drive a Chevy”… Rest assured that things are almost as complicated: while there may not be 6 computers there is at least one, if not more.

While it may seem overly complicated to have all of these computers, and in some cases I believe it is, there are specific reasons for it. First, the number of wires in the car is reduced substantially and second, functions in the car are easily integrated. An example is your door lock system flashing the lights and tooting the horn when locking or unlocking your door with the key fob. With that basic system in place adding an alarm function is easy. This is a simple example of the many ways that your vehicle’s electronics coordinate many functions.

There you have a little insight into why a seemingly simple problem can take way longer to fix than you expect and cost what it does. The realm of the Auto Service Technician is complex and the tasks that we must perform in order to keep your car in great shape require expert knowledge and ongoing training.

About the author 

Bernie Pawlik

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