Written by: Erin Vaughan - President, CEO and Journeyperson Automotive Service Technician
Your Vehicle Won't Start. What Should You Do?
What Does a Backup Sensor Have to Do With a Vehicle That Won't Start?
You turn the key, hear a click, and the engine doesn't turn over. Bad starter, right? Maybe! But sometimes the problem is somewhere you'd never think to look.
We once had a 2009 GMC SUV come into Kinetic Auto Service with an intermittent starting problem. Most of the time, it started perfectly. But every few key turns, the driver would turn the key, hear a click, and nothing would happen. It certainly acted like a bad starter.
The client had already tried replacing the starter relay, hoping that would solve the problem - unfortunately, it didn't. That's where proper diagnosis became especially important.
Following the Evidence, Not the Symptoms
Rather than replacing more parts and hoping for the best, I followed the manufacturer's diagnostic procedure. Testing revealed that the voltage reaching the starter relay was too low. That gave me an important clue: the problem wasn't necessarily the starter itself, something was interfering with the signal needed to activate it.
As I continued testing, I discovered something surprising - a faulty rear backup sensor could interfere with the vehicle's communication network and prevent the starter signal from reaching the starter relay correctly. Modern vehicles use electronic communication networks, often called CAN bus systems, to allow different components and computers to communicate. When something disrupts that communication, the symptoms can appear completely unrelated to the component causing the problem.
In this case, the culprit was a shorted rear backup sensor! I disconnected the sensor, and the voltage at the starter relay returned to normal and the SUV started normally every time. Replacing the faulty backup sensor resolved the problem!
Think about that for a moment. A vehicle that appeared to have a starter problem was actually being prevented from starting by a sensor at the back of the vehicle. Without following the diagnostic procedure, it would have been easy to replace the starter, battery or other components without fixing anything.
That's why we believe in diagnosing the problem before replacing parts!
What Happens When Your Vehicle Won't Start?
Not every starting problem is as unusual as that GMC. But the symptoms can provide useful clues about where to begin.
1. The Engine Cranks but Won't Start
If you hear the engine turning over normally but it won't actually run, the starting system is doing its job. The problem could involve fuel delivery, ignition, electrical components or a mechanical issue.
If your engine cranks but won't start, we generally recommend arranging a tow so the vehicle can be properly diagnosed.
2. You Hear Clicking, but the Engine Doesn't Turn Over
Clicking can indicate a weak battery, a poor electrical connection, a faulty starter or a problem with the starting circuit. Also, as our GMC story demonstrates, sometimes the cause is much less obvious.
One of the first things we'll ask is whether you've tried boosting the vehicle.
- If boosting doesn't work: The vehicle will generally need to be towed in for diagnosis.
- If boosting gets it started: Bring it in for a starting and charging system assessment so we can determine why it wouldn't start in the first place.
A Successful Boost Doesn't Mean Your Battery Is Bad
It's easy to assume that if a boost gets your vehicle running, the battery must need replacing, but that's not necessarily true.
A vehicle can have starting problems because of:
- A weak or failing battery
- An alternator that isn't charging properly
- A worn or slipping alternator belt
- An electrical draw that drains the battery while the vehicle is parked
- A faulty starter that draws excessive current during cranking
- Damaged wiring, poor connections or other electrical faults
That's why we test the system before recommending repairs! Learn more about our battery testing and electrical diagnostic services and alternator and charging system repair services.
The Right Diagnosis Can Save You Money
Our GMC client had already tried replacing a starter relay. It was a reasonable guess based on the symptoms, but it didn't solve the problem. Imagine if the next step had been replacing the starter, the battery or the alternator. Those repairs wouldn't have addressed the shorted backup sensor.
The point isn't that every no-start condition involves an extremely complicated electrical problem - most don't. The point is that the symptom tells us where to start investigating, not necessarily which part to replace.
At Kinetic Auto Service, we take a systematic approach to diagnosing vehicle problems so we can recommend repairs based on evidence rather than guesswork.
We stand behind eligible repairs with our 3 year/60,000 km Peace of Mind Warranty.
Vehicle Won't Start? Here's Your Next Step
You don't need to know whether it's the battery, starter, alternator or something else before calling us - just tell us what happens when you try to start your vehicle. We'll help you determine whether it should be towed in for diagnosis or brought in for a starting and charging system assessment.
Call us or book online to arrange professional vehicle starting and electrical system diagnosis.
