How to fix a slow cranking starter

Problems with cranking don't necessarily indicate a faulty battery. Dreamstime/TNS

Q: My van has begun to crank hard at times as if the battery is low. So far it hasn’t required a jump start, but it’s probably only a matter of time. I had the battery tested, and it’s supposed to be OK. Can you suggest what can be checked next? I’d like to try some things before going to a shop.

Table of Contents Show

1) Identify the Problem
2) Initial Checks
3) Slow Crank Issues
4) Click, No Crank
5) No click, no crank

Drake

A: Let’s look at the most likely causes for slow cranking and how you might check for them.

Battery condition: most batteries last about 4-7 years, depending on their environment and usage. After a lengthy drive (with a good charging system, 14 volts showing on gauge) or an overnight charge, try the following: Disable fuel or spark and crank the engine for 15 seconds with a voltmeter attached to the battery terminals, preferably the posts. If the voltage dips below 11 volts while the starter is operating, the battery is likely in poor condition. Be sure the cable connections are clean and tight. Repeat the test after cleaning/tightening if there’s any doubt.

Discharged/low battery: Resolve this before blaming battery condition. This can be caused by insufficient charging (due to short trips mostly or poor alternator performance). Try this: With voltmeter attached to the battery terminals, turn on headlights, front and rear defroster (fan on high) and check voltage while idling. If it’s below 13.5 volts, the charging system is suspect. Check belt tension.

Parasitic drain: This is a situation where an electric component is consuming energy while parked and discharges the battery. A tiny amount is normal, to keep module memories alive. Does your slow cranking depend on how long the van has been parked (e.g., it’s worse after being parked more than overnight)? If so we’re on the right track. Try this: With the key off and doors closed, check visually for any illuminated lights _ glovebox, courtesy, rear area or under hood — and listen for anything whirring or clicking, and feel the alternator for warmth (after overnight). Testing for parasitic load using a digital volt/ammeter is the next step. Due to vehicle diversity and space limitations to explain methods, this is best referred to a pro.

Cable connections and starter condition: If it’s possible to access the starter safely and conveniently, checking voltage delivered to it while cranking will prove this one way or the other. Connect voltmeter red lead to the large starter input terminal and the black lead to bare starter metal. With a strong battery, while cranking, a reading of 11 or more volts indicates good voltage delivery (battery and cables/connections). Should the starter crank poorly with this or better voltage applied, it’s suspect. Less than 11 volts while cranking usually indicates a problem with the battery, cables or cable connections.

Using an inexpensive digital voltmeter to check for proper vehicle readings is a safe and highly effective means of checking poor component operation when precautions are followed. Be sure to remove hand/wrist jewelry, stay clear of hot or moving components, wear eye protection, and never work beneath a vehicle that isn’t carefully supported. The meter’s high input impedance protects both the circuit and user should a boo-boo occur with connections when measuring voltage.

In most cases, voltage is checked while the circuit is active; that’s when one may see unwanted voltage drops, which are often the problem.

A good circuit will deliver 90 percent or more battery voltage (which varies with load) to the component as it’s operated. If a component works poorly with good voltage delivered to it, it’s faulty. When testing a component that doesn’t work at all, one checks for where voltage is present and where it’s not as operation is attempted.

If you are in charge of a commercial vehicle fleet, you know how important it is to ensure all your vehicles perform in peak condition. With all the work the fleet does, you can’t afford to have a vehicle in the shop for very long while you diagnose what may be going wrong with it.

If it is a cranking issue, there’s an easy way to quickly narrow down what may be affecting the vehicle, saving you time and energy on the initial diagnosis. We live and breathe starters, so here’s a bit of inside info.

1) Identify the Problem

Before tearing the vehicle apart, take a moment to fully understand what is keeping it from successfully cranking. What it’s doing, or not doing, can give you some clues as to what step to take next.

Slow crank: The starter cranks, but it does not produce enough engine RPMs to successfully start the vehicle.
Click, no crank: The solenoid clicks, but the starter fails to crank at all.
No click, no crank: The solenoid isn’t clicking, and the starter isn’t cranking.

No matter what the problem is, the initial steps you take to diagnose the problem up front are the same.

Your first check is the battery bank.

2) Initial Checks

It’s one of those things you could forget about only to smack yourself in the forehead after hours of searching for the cause. First, always test the battery. Here are the steps to follow:

Step 1: Fully charge the battery, then perform a load test.
Step 2: If the load test fails, begin checking each battery individually. If you have a bad one, replace it.
Step 4: Once all batteries are tested, perform a voltage drop test on the starter main cables. Voltage should be less than .5V. This is an important step in the diagnosis of a problem.
Step 5: Voltage drop can often be the cause of slow cranking. However, it can also be a root cause of a click or no-click problem, because of how almost every manufacturer wires the heavy positive post to supply power to the control circuit.

Combined with what you know about the problem, these checks should give you an idea of how to proceed.

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3) Slow Crank Issues

If the vehicle fails to start due to slow cranking, and the battery and cable checks are okay, you know the control circuit must be functional. Knowing this information, you can confidently diagnose the problem as probably being related to a bad starter. Replace the starter, and your issues should be remedied.

4) Click, No Crank

When it is a click but no crank issue, and the battery and cables check out:

inspect the control circuit.
If your vehicle has an integrated magnetic switch (IMS), perform a voltage drop test.
If there is an IMS, verify that the control circuit is supplying voltage.

5) No click, no crank

The no click, no crank complaint is perhaps the easiest of the bunch to figure out. If battery checks come back alright, you can almost assuredly narrow the root cause down to power not reaching the solenoid. Typically this is not an indication of starter motor problems.

No matter the issue, if the starter is found to be the faulty component, you should also perform a check of the ring gear. If it is damaged, it could continue to cause starter problems in the future.

To make sure your fleet spends as little time as possible in the shop with cranking problems contact a member of our team today. We’ve got the best parts at the best prices to keep your fleet running smooth.

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