Help My Car Battery Won’t Jump Start

There could be several reasons why your battery won’t jump start and they all don’t necessarily have to do with the battery.

But let’s start with the starting battery, because it’s the easiest place to start looking for why your car won’t jump start.

Signs of a dead battery

Are your dash lights not coming on?
Are your headlights and interior lights not coming on or weak?
Was there a light or other device left turned on overnight?
When you attempt to start the car do you hear rapid clicking sounds?
These are signs of a weak or dead battery.

Tips For Jump Starting A Car

Make sure you have cleaned and checked for loose battery cables.

This is often over looked but dirty or loose cable connections at the battery will not only cause dead battery conditions, but also makes jumping difficult.

Check out your jumper cables themselves. Small gauge cables are notoriously unable to transfer enough juice to adequately power up the dead battery.

Make sure the clamps of the jumper cables are secure and have a good “bite”.

Always, and I do mean always, make sure your last connection is the black negative cable, and never, and I mean never, connect it to the battery itself. Always make your last connection to a sturdy metal part if the car away from the battery. Sparks can ignite hydrogen gas that the battery produces and cause an explosion.

Start the good car and it may take a minute or two for your car to turn over fast enough to start.

Never, and I mean never, leave your car unattended while jumping. You want to make sure nothing is getting excessively hot. Make sure you don’t see smoke coming off of the cables, clamps, or batteries. If you do, immediately disconnect the black negative cable that you attached to a sturdy metal part.

Excessive heat or smoke may indicate something other than battery failure. At any rate, cables heating up can lead to a car fire.

That’s what happened in this video.

More Jump Starting Tips

Many times if your car won’t jump start, it’s the quality of the clamp connections. Check and recheck to make sure you’ve got a seriously good and solid contact.

Sometimes relocating the black negative cable to a different metal part will do the trick.

In some extreme cases I have hooked the cables directly to the starter motor, bypassing the battery. This isn’t always that practical though. Especially if access to the starter is limited.

If everything fails, you may have to just replace the battery. This is why I always like to carry a portable jump starter like the Clore JNC660 Jump Starter, or AntiGravity’s Micro Start.

This is how I know I’ve got a good power source with good cables and clamps to get me out of a dead battery situation. You can check out my review of the JNC660 here, and the Micro Start here.

Now let’s take about some other problems that mimic a dead battery situation and prevent you from jump starting your car’s battery.

Dead Car Battery Impostors

The main culprit is the starter motor. The starter could be worn out and if you just assume it’s your battery and try to jump it you are just spinning your wheels.

Here’s a quick way to determine if the starter is bad.

Turn your head lamps on. If you cannot observe the light intensity have someone else turn the key all the way over to start.

If your battery is weak or dead your head lights will dim significantly. If the starter is bad then the head lamps will stay bright.

Other electrical components can also be at fault, but the most common one is a worn starter.

Worn Starter Motor Trick

What I have done when I want to squeeze a few more starts out of the starter motor is to find something that I can tap on the body of the starter with.

I’ve even used a tire iron to tap on the starter body and solenoid. You need to tap it kind of hard. The idea is to free up some dust, or to free up the starter’s brushes to make one last contact.

I have saved myself and many stranded motorists this way. At least you can get home or to a shop and have the starter replaced.

Here’s a great video demonstrating the starter trick. It also shows many of the jump starting tips, and sounds I wrote in this post.

Bad Neutral Safety Switch

Another less common problem that can actually mimic a bad battery and a bad starter is a bad or misaligned neutral safety switch.

I had a friend who drove over a deep pot hole in a parking lot and after he had parked the car and was ready to leave the car made no noise at all, but the dash lights and head beams came on.

I immediately suspected the the neutral safety switch since his selector was on the floor and not on the column, and running over that pot hole could have caused the switch to get misaligned.

I got his car started by keeping the key all the over to the start position while carefully and slowly moving the shift lever out of the neutral position.

I was moving it half way up and back down until the neutral safety switch thought if was in neutral and allowed the car to start.

Main Battery Fuse Blown

This dead battery impostor can easily fool people into replacing batteries, because it perfectly mimics a completely discharged battery.

It will also be a reason why your car won’t jump start.

The main battery fuse can be blown essentially causing the positive cable of the battery to not be connected.

All your power will be gone, that is, no lights, no dash lights, no radio, and of course no starting.

The way car makers accomplish this fuse protection varies a lot so it’s difficult to give precise instructions on how to locate and diagnose in an article like this.

I only mention it here to give you a heads up on other possible causes for cars not jump starting.

In this situation, you could try to connect only one cable of your jumper set from the positive (red) post of the battery to the positive connection of the starter motor itself.

Be very careful that you connect to the battery first, then to the starter motor so that you won’t have any sparks at the battery.

Here’s a video on exactly what a blown main fuse looks like on a Nissan. Be for warned though, the mechanic in the video uses some colorful language.

Seized Engine Worst Case Scenario

One last possibility for why a car won’t jump start is that the engine or transmission has locked up or seized up.

This is worst case scenario and thankfully not too common, but it happens enough to warrant mentioning.

A seized engine has a very distinctive one loud click noise when trying to start the car. Sometimes it could even sound like a thud or clank.

Here’s a video that demonstrates what a seized engine sounds like.

At this point a tow truck is in order.

Conclusion

These are the common general reasons why you could have difficulty jump starting your car battery. There always could be other less common things like a bad ignition switch for example.

Hopefully you got your answer here. If you found this helpful don’t forget to “like” and “share”.