When your truck won't start, it could be many possible culprits. Know what to look for to determine if it's a battery, alternator or starter problem.

When your truck, semi or any vehicle doesn’t start (especially in the cold), many possible problems may come to mind. Don’t panic. Our experts at Wheelco are here to help. That’s why we’ve put together a checklist of possible culprits for you to inspect when your truck doesn’t start.

  • Battery
  • Alternator
  • Starter

Components of the Heavy-duty Electrical System

The heavy-duty electrical system is made up of the starting system and the charging system. These systems are, in turn, comprised of batteries, the starter, the alternator, the interconnecting wiring and electrical and mechanical switches. For maximum operating efficiency, all parts of the system must be functioning properly. If they aren’t working top-notch, we’ve identified some signs and symptoms to check, testing and inspection options, as well as recommendations and next steps.


Signs You Need To Replace Your Battery

There are many warning signs that it might be time to replace your battery. They are several things you can look for when determining if your battery is on the fritz. If it’s slow or no cranking, low volt meter readings, dim lights or slow turn signals. If you notice that any of these are occurring, then it might be time to come and get a replacement part.

Hint: If you jump your truck and the engine starts and runs, but won’t turn on again after turning off. It’s probably the battery. This means the alternator is working. The alternator’s job is to keep the vehicle running after it’s started. In this scenario, the battery can’t hold a charge after when the alternator is off.

Test & Inspect Your Battery

Inspect cables for broken jumpers or main terminal ends. Green or corrosion means resistance, and the batteries may not be getting a proper charge. You can also use a hydrometer or load tester to test your battery.


Depending on the age of the batteries, Wheelco recommends replacing all the batteries at the same time. For example, replacing one battery when the other two or three are a couple years old will impede the new battery’s performance. It will actually slow it down to the state of the older batteries after it has been installed. This is why Wheelco recommends replacing an entire set of batteries at the same time rather than piecemeal.  Our experts use Deka Batteries in their vehicles.


Signs You Need To Replace Your Alternator

Some of the same signs for a dead battery may actually be due to a failing alternator. When alternators fail to charge you may experience the same slow cranking or feeling of a dead battery. Alternators will also have an overcharge state if the regulator sticks or goes bad. If overcharging occurs, boiling at the battery(s) can be seen. Additionally, if your headlights or the lights in your dashboard flicker or get extra bright momentarily, it’s also a sign of a failing alternator. Lastly, you might notice the stench similar to rotten eggs or burnt rubber. If so, it’s time for a replacement.

Hint: If you jump your vehicle, and the engine dies right after it’s jumped, it’s probably your alternator.

Test & Inspect Your Alternator

To determine if it’s your battery or alternator that’s failing there are a few tests you can do. Visually inspect the cables at the back of the alternator, starter, and batteries. If no loose or broken connection(s) are found, the alternators can be tested using a voltmeter. An alternator that is running properly will have a reading from 13.6 – 14.2v when charging.


If it’s your alternator, Wheelco stocks premium brands like Delco Remy and Meritor. Our mechanics and experts trust these brands in their own vehicles.


Signs You Need To Replace Your Starter

The starter is responsible for starting the engine. It does this when the battery sends volts of electricity to the starter. The starter then uses this energy to turn the engine over. Thus, starting it.

Like batteries and alternators, failing starters have signs, you just have to be on the lookout. There may be a clicking sound when you turn your key switched. Others can be a spin with a no crank scenario. Others can be a slow start before your engine turns over. However, a low voltage is the main culprit of running a starter. If a batteries voltage gets low, most tend to jump or crank, but will eventually start your engine. It might just take a little time to start your engine. If you notice this jumping or cranking, don’t wait! The more times you do so, the more damage you can cause—and not just to the starter.

You might be asking yourself if it’s eventually turning over, can’t it wait to be replaced? We don’t recommend waiting because it can cause more problems, costing you time and money. When cranking your starter with low voltage, the discs in the starter’s solenoid can actually burn or even arc together. Eventually, the solenoid will fail/weld completely together. If this happens, the starter will continue to crank, even after you let off the key switch. We recommend replacing them before that cold winter morning, and you can’t get your vehicle started.

Hint: The car won’t start but the dash lights will turn on means that your starter is probably failing. Jumping your vehicle will not help turn the engine over—this indicates a failing starter as well.

Test & Inspect Your Starter

As we mentioned earlier, resistance is a big deal in an electrical circuit. Bad or green cables which cannot be seen from the outside can cause big problems between the starter, alternator, batteries, etc. The cables must be checked with a load test or check the voltage drop per cable. It should not have over a .5v drop per cable. At Wheelco, we recommend installing new cables to help with the slow cranking due to high internal resistance.


For all your starters and cables needs, ask one of our experts at Wheelco. You want the best when it comes to your vehicle, which is why we stock premium brands like Delco Remy and Meritor.

Professional Service and Expert Advice

Wheelco Truck & Trailer full-service repair shops provide complete electrical system services. Whether it’s your battery, alternator or starter, Wheelco is your service center. Our professional, industry-trained mechanics use the latest technology and tools for diagnosis.  Diagnosis is the three-part process that begins when a problem is perceived and ends when the equipment is confirmed as serviceable. The process can be described by using three questions that must be answered to assure the completion:

  1. What are the symptoms? This is what has been observed (seen, heard, felt or smelled) that indicates a problem.
  2. What caused the symptoms? This involves using diagnostic procedures to identify the root cause of the problem.
  3. How do we fix it? Usually, this involves the adjustment, repair or replacement of some or part or all parts.

Wheelco Services offered in Sioux Falls, SD, Mitchell, SD, and St. Paul, MN.

  • Diagnostic Troubleshooting
  • Component Benchwork
  • Starter Diagnostics and Replacement
  • Alternator Diagnostics and Replacement
  • Battery Diagnostics and Replacement
  • Cable & Wire Replacement
  • Lighting Installation & Repair
  • Computer Controls / Multiplex Wiring
  • Preventative Maintenance & Inspection

Our in-stock, premium electrical parts to include: batteries, starters and alternators, wire and cable, and various electrical components, we’re sure to get you back on the road quickly. Need more help! No problem. Consult with a service technician at Wheelco. Our experts are ready to help!