I just had an extended conversation with a new customer about the diagnostic tests needed to locate the problem with his truck and get it repaired. He didn’t understand why the diagnostic tests were needed and why we would charge to locate the problem then charge for the repair too. I get it. Folks get confused about automotive diagnostics, especially when an auto parts store tells the customer they do Free diagnostics. “Can’t you just plug in your machine and have it tell you what’s broken?”
Like I’ve said in a couple other articles, your car is a complicated device. And it’s device full of computers. Most modern cars have as many as 50 microprocessors with a lot of high end cars having many more. When we’re doing diagnostics we’re dealing with one of those computers or a system monitored by one. Our scanner, the diagnostic machine, tells us what system is affected or what the monitoring computer believes is affected. Sometimes it takes us right to the issue, sometimes not so much.
What kind of systems are we talking about? Well, fuel metering systems, ignition systems, evaporative emissions control systems, transmission control systems, anti-lock and traction control systems, supplemental restraint (airbag) systems, climate control systems, even electric windows and power seats.
In this particular case the customer had come to us with the Check Engine Light on and we pulled a code indicating a fault with the idle air control motor (IAC) or circuit. When we opened the hood we found a new IAC already installed, it also had a new power train control module (PCM). The customer had been to the fore mentioned auto parts store and they had retrieved the same code we did, sold the customer a new IAC and sent him down the road. When he installed the new part it didn’t solve his problem so he brought it to us at All Tune and Lube Total Car Care Tempe. Turns out his original IAC had shorted, burning out the IAC control circuit on his PCM. New quality IAC and a fresh remanufactured PCM and the customer gets his car back without the problem.
I guess the bottom line is that if there’s a code in your cars’ computer for a random misfire don’t let an auto parts store tell you you need a tune up. You may well but it may also be something else. Have a professional diagnostic done and get the car repaired!
From your Local Mechanic, All Tune and Lube Total Car Care Tempe. Complete Auto Repair and Maintenance.