Computer Scans, Indep Mechanic vs Dealership

Is there any advantage to having a dealer, rather than a good independent mechanic, plug your car into the device that scans the car’s systems for problems and then lists codes to identify what the problems might be? Don’t they pretty much use the same types of scanners for this type of analysis?

(My specific situation, girlfriend’s 93 Corolla has had airbag light on for some time. Independent mechanic did computer scan, which “intermittently” identified the source as the clock spring. Replaced it, which did’t solve the problem. Mechanic suggested taking car to dealer for computer scan, which turned up two possibilities: airbag computer and clock spring again. I’d think today that independents have to have the ability to scan the cars, since computers play such a big part in so many car systems.

Thanks for shedding any light on this.

Anyone can do a OBD-II engine scan. Unfortunately, air-bags fall into the “proprietary” category, controlled by a separate micro-processor. The diagnostic tools needed for diagnosing air-bag problems are different. Some manufactures are better about sharing this information than others. The control boxes are expensive. See if you can find a used (salvage) one before you spring for a new one. Your '93 model is too old for repair shops to worry about buying expensive scan tools for…

Thanks. When you refer to the control box, are you talking about the air bag computer?

This car is pre-OBD2 its OBD1, I don’t envy anyone trying to fix a OBD1 equipped car. Air bag diagnostics in 1993 were at best primitive and your best bet is finding someone who has worked with 1993 air bag diagnostics extensively.

Its going to have to do with the capability of the scanner AND what the problem is with the vehicle. The dealerships scanning equipment is usually equipment designed for that manufacturer meaning it is specially made for that manufacturers vehicles so it should be able to test anything testable on their vehicles. There are plenty of scanners out on the market, each with their own capabilities and prices ranging from $100 for a basic code reader into the thousands for full fledged high end scanners. The scanner I use I have $10,000 invested in, and that does not include $2,400 a year to update the software. I can do about 99% of what a dealership scanner will do. I can do flash updates to ECM’s and TCM’s. I also have a 4 channel lab scope, graphing meter, component tester, DVOM and a troubleshooter built in. I can do just about anything a dealer can do except program key FOB’s. So, depending on what kind of equipment the independant has will mean whether he can solve your problem. In your case having a pre OBD-II vehicle, and with it being an airbag problem you are going to need to find someone with a SCANNER that can test air bag modules. Its kind of a toss up though. An independant could charge you $70 or $80 for a scan (Diagnostic) using a scanner not capable of helping him find your problem. You pay him and he sends you to the dealer and you pay another $100-$120 for them to scan it. I would always try a good independant before even considering a dealer.


Appreciate all the help. You guys are great.