Rick's Free Auto Repair Advice

Car questions and answers

How to get answers to your car questions

I volunteer on a lot of car forums so every day I deal with car questions and answers. But the one thing that drives me crazy is when someone asks a car question but doesn’t give critical information like year, make, model, and engine. They must think that every vehicle is designed, configured, wired, and plumbed exactly the same way. They’re not. In fact, car and trucks differ so much from make to make that it’s nearly impossible to answer even the simplest question without knowing the year, make, model and engine. Vehicles also differ from year to year and model to model.

 

I’m talking about questions like, “my car won’t start, I turn the key and get a clicking sound, there’s a squealing noise when I turn my wheels, my car dies, the lights come on on my dash, or my favorite; my headlights don’t turn on. “

 

In the old days, most switches actually switched power to the starter, headlights, windows, etc. But not anymore. Most of those switches are just inputs to a computer. It’s the computer that activates a relay and the relay switches power.

Here’s why we MUST know year, make, model, and engine

Here’s an example. In many new cars with anti theft features, turning the ignition key to START just sends a signal to the main powertrain control module. Before the PCM allows power to flow to the starter motor, it first has to check to make sure you’re using a legitimate key. In some anti theft systems, the checking mechanism is located inside the lock cylinder, while in others it’s located in a sensor around the lock cylinder. Some keys have transponders, others relay on the signal sent when the lock cylinder turns. Older systems check an electrical resistor located in the key itself. If the key passes the security test, the computer then checks to make sure the transmission is in Park or Neutral. That involves sending a digital message to the transmission control module TCM (if that particular model even has a transmission control module). If the TCM confirms a park/neutral position, then the computer communicates with the body control module BCM (in some vehicles) telling it to activate the starter motor relay located in the engine compartment junction box. That relay is powered by a fuse. The BCM activates the relay by either providing ground or power to the relay control coil circuit. THEN, once that relay is activated, power flows through the relay contacts and down to the starter solenoid. THAT solenoid pulls in and switches power to the starter motor.

 

See how many steps are involved? So when you post a question like, “Why won’t my car start”, without giving us year, make, model, engine information, we just shake our heads and wonder what world you live in.

 

PATTERN FAILURES

Then there are pattern failures and technical service bulletins. Here’s another example: long before GM admitted it had an ignition switch problem, mechanics starting seeing very unusual behavior in GM vehicles. Owner’s complained that their cars would randomly stall or randomly not start. There was no rhyme or reason to the problem. But after a while, shops began to see the pattern—the ignition switches were failing at random. There’s a company that specializes in tracking these kinds of problems and they offer a subscription service to shops so the shops don’t waste time reinventing the wheel for a pattern failure. Using the same “My car won’t start” question, I could give you a dozen reasons why it might not start based on general car info. But the second I know that you’ve got a late ‘90’s GM, I can tell you exactly what to check first. Now do you see how important year, make, model, engine information is?

Technical Service Bulletins

No auto tech worth his pay will start diagnosing a problem without first checking the manufacturer’s service bulletins. Honestly, the most common problems already have been discovered by the manufacturer and they’ve come up with a solution. More and more we’re seeing a software fix coming from the manufacturer. It’s literally a software update to fix a factory bug in the software. In other cases they’ve redesigned the part and issued an updated part. Still, in other cases they’ve discovered where a factory wiring harness is rubbing against another component and the fix involves moving the harness.

 

But in order to find the bulletin that relates to your problem, I’ve got to know the year, make, model AND which engine you have. Leave that information out and you’ll get lousy answers.

 

I’ve seen people give the worst possible answers simply because they’re not aware of a factory service bulletin or a pattern failure. That’s when I see somebody write in a second or third time after spending hundreds on unnecessary parts. Finally, they cough up the critical information.

 

So, if you REALLY want help with Car questions and answers, follow these rules.

 

MANDATORY INFORMATION:

 

  • Year, make, model, engine size (not just v-6, but exactly which engine is in your vehicle)

 

Don’t know the year? It’s the 10th digit of your VIN number. See the chart below.

 

VIN number

VIN year converter. 10th digit

 

 

 

 

 

 

 

 

 

 

 

 

Don’t know which engine is in your car or truck. It’s usually the 8th digit. But give us the entire VIN number and we can look it up for you. Here’s what happens when I try to look up pattern failures and service bulletins for a 2005 Ford F-150

engine size

Ford offered 5 different engines for the F-150 in 2005. Each one has its own pattern failures. But I can’t find them if you don’t tell me which engine you have.

 

  • Describe the problem in some detail.

“My car won’t start” isn’t helpful at ALL.

Does it crank but not fire up?

Does it do this first thing in the morning? After you’ve driven it for a while? When it rains? What’s the pattern?

Doesn’t crank?

Just clicks when you turn the key?

Clicks rapidly?

  • The same thing applies to noise complaints

Does it make the noise at idle? When accelerating? When turning corners? When braking? When backing up? When you shift it into gear?

 

 

  • And about those leaks and cooling problems

 

What color is the leaking fluid? Which reservoirs have you filled?

What diagnostics have you done so far? Did you clean the front of the radiator? Have you changed any parts?

Provide good information and you’ll get good help. Leave it out and you’ll get really STUPID answers.

 

©, 2015 Rick Muscoplat

 

Posted on by Rick Muscoplat


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