Mechanically Speaking: ‘Known good part’ not always best answer

"Many times automobile components cannot really be tested step by step. There is no simple method of testing them."

“Replace with known good part” is a statement that you used to come upon often when trying to diagnose what is wrong with a customer’s vehicle. The Japanese vehicle repair manuals seemed to rely on this step frequently. It was often used in the process of elimination deep within a diagnostic trouble tree.

Trouble tree? That is one of those flowchart things that asks your mechanic to perform certain tests where the outcome establishes the next step in solving a problem. If the voltage at connector B1 pin 36 is greater than 11 volts then go to step five otherwise go to step seven. Get my drift?  Many times automobile components cannot really be tested step by step. There is no simple method of testing them.

Some manufacturers believe that their mechanics have no need for any inside information on the way certain parts work. When your mechanic establishes by following the flowchart that all the signals going into a part are correct and all the wires leaving that part are in working order then it is time to replace the part with the aforementioned “known good part”.

We all (auto mechanics in general) have a dusty shelf or bottom deep tool box drawer harboring some known good parts. The known good parts of choice were ignition modules and alternator voltage regulators. You might have a wiper motor or an idle speed control motor as well.

In every group of technicians there are those that have a much larger selection of known good parts. These types are the ones that skip the testing part of the trouble tree and go straight to the known good part swap. It can be faster. And it sells parts. Does it make satisfied customers? I do not think so. A lot of good parts are replaced with good parts.

Modern day technology is making part swapping a very costly approach to diagnostics. In many cases it is now impossible. A modern automobile is a myriad of electronic parts. Many of these electronic parts are essentially small computers.

Most of these small computers are programmed to operate with the car they were installed in originally. The software within them may be locked to the car.

Most vehicles now have some type of immobilizer system (anti theft system)  built into them. When you put the key in the ignition and turn it or push the start/stop button a series of secret handshakes ensues. All the handshaking modules must be satisfied that they belong together.

Take the engine control computer from a running identical vehicle to your own and install it and it will not work. Without technical wizardry the other modules in your car will not shake hands with the intruder.

Fortunately some manufacturers make it possible for your mechanic to program their modules to work in different vehicles. This makes a known good used part a possible solution to certain automotive woes.

To succeed, programming equipment and access to the manufacturer’s software must also be in your mechanic’s drawer along with the known good parts.

Trail’s Ron Nutini is a licensed automotive technician and graduate from UBC. E-mail: nutechauto@telus.net

 

Just Posted

Snowfall warning in effect for Kootenay Boundary

Environment Canada warns of heavy snowfall over night, flurries for Wednesday

Trail auxiliary shares proceeds from gift shop

The funds will go to various Kootenay Boundary Regional Hospital departments

Renter beware: Online rental scam happening in Trail

Don’t be giving anyone money if you can’t get keys to have a look or meet the person, realtor warns

Rossland group builds hiking trail FORR everyone

The project will allow people with mobility issues to enjoy the trails in the summer

2019 Colombo Lodge executives

The 2019 men and ladies executives were sworn in at the installation ceremonies earlier this month

VIDEO: Here’s what the B.C. legislature officers are accused of buying

Personal trips, purchases, alcohol and more laid out in 76-page report by Plecas

Former Blue Jays ace Roy Halladay voted into Baseball Hall of Fame

M’s legend Edgar Martinez, Rivera, Mussina also make the grade

Why would the B.C. legislature need a firewood splitter?

First sign of police involvement in investigation of top managers

New Canada Food Guide nixes portion sizes, promotes plant-based proteins

Guide no longer lists milk and dairy products as a distinct food group

Judge annuls hairdresser’s forced marriage to boss’ relative

Woman was told she’d be fired if she didn’t marry boss’s Indian relative so he could immigrate here

Liberals look to make home-buying more affordable for millennials: Morneau

Housing is expected to be a prominent campaign issue ahead of October’s federal election

Cannabis-carrying border crossers could be hit with fines under coming system

Penalties are slated to be in place some time next year

Man accused of threatening to kill ‘as many girls as I see’

Christopher W. Cleary wrote he was angry because he’d never had a girlfriend and wanted to ‘make it right’ with a mass shooting

Most Read