Jeep Wrangler Cranks but Wont Start

It is very disappointing when your beloved Jeep makes you late for work. If you leave home early after a short breakfast and discover that your jeep wrangler cranks but wont start, you’ll obviously feel frustrated. On one hand, this problem appears suddenly. On the other, you’ll have to go through the ordeal of finding a solution.

Know that the revelation of the actual problem will only require a few simple tests for the fuel and spark. Although, the situation can be a little serious if your engine doesn’t even crank. If you turn the key to your beast and there is no cranking, you need to worry a little. Quite many and complex electrical components are utilized in making a Jeep Wrangler.

A JK Jeep Wrangler utilizes a Total Integrated Power Module to control and communicate with other electrical systems throughout the vehicle. There can be some technical flaws in the TIPM and the adjoining electrical systems that would prevent the normal cranking of the engine.

Ascertain the possible reasons behind your engine that won’t start

One must consider the simplest reasons first. It is possible that your vehicle has a shortage of fuel. This is the most common reason why an engine won’t start even after cranking. Another reason could be an absence of spark. Although, the commonest reason behind this problem is always related to a starter motor that wouldn’t spin the engine and let it start. A series of simple tests need to be performed to analyze the real issue behind this symptom.

Examine some essential parts to figure out the real problem

You’ll need some specific materials to perform a few tests. These simple tests will help you establish the real reason behind your Jeep’s engine that cranks but doesn’t start. To perform these tests, you’ll need a battery tester or a digital multimeter, a metric wrench set, a battery charger, and a fused jumper wire.

Examine the battery of your Jeep Wrangler

A low or dead battery is very often found as a culprit behind an engine that doesn’t start. Car batteries have a limited life span. The earlier batteries used to be large up to five years. Now their age has reduced to three years. This is essentially because of their regular exposure to extreme weather conditions, especially the cold in the winter months. You may not have expected this, but not driving your Jeep regularly could also deteriorate its battery.

While the cold temperature makes it difficult for the battery to start, the irregularity in driving leaves the battery unoperational for enough time to discharge. Moreover, Jeep owners often take their beasts through rough terrains and tough off-road paths. Excessive obstacles and the concurring vibrations in such paths can also affect the health of the battery.

One must note that even when you don’t drive your Jeep, the advanced electronics and alarm systems continue operation and drain the battery. This is why it is relatively common to come across failed Jeep batteries. Even if it has been maintaining a full charge over a prolonged duration, your Jeep’s battery can fail sometime. So whenever you discover that your Jeep won’t start, you should first examine its battery.

Use a battery tester or a digital multimeter to correctly examine your Jeep’s battery voltage. For a healthy battery, the voltage will be above 12.0 volts. A fully charged Wrangler’s battery will show a voltage of 12.6 volts. And if you discover that your battery has a relatively low voltage level, it should be charged.

If you place a load on the battery and examine with the help of a battery tester, it should show 75 percent charging in optimal conditions. A significant drop in battery voltage would indicate a failed battery. You must check the tightness of the battery cables to ascertain that sufficient current is flowing through the starter to push the engine.

If your battery is alright and the engine still won’t start, examine the ground straps.

Examine your Jeep’s ground straps

Corroded or broken ground straps could also be the reason behind your stubborn engine. Ground straps are responsible for supplying the current back to the battery after it has flown through the other electronic components of the vehicle. The JK Jeep Wrangler utilizes a ground strap that extends from the battery’s negative terminal to the block housing of the engine. This strap has been known to corrode and break at times.

The starter of the engine utilizes a large amount of energy from the Jeep’s battery for optimal operation. Any excessive resistance in the circuit would create issues in starting your Jeep Wrangler. Examine the ground straps and make sure they are tight. Many experts recommend that you install an extra braided eight gauge ground strap to create sufficient electrical ground.

If the ground straps are secure with no evident corrosion and the starter still wouldn’t operate, check your vehicle’s safety switch.

Check your safety switch

Your Jeep is equipped with some protective features that aim to stop it from getting started while in gear. While this is an important safety mechanism, it can at times create hurdles in the normal operation of your Jeep’s engine. Your JK Jeep Wrangler does not have the traditional neutral safety switch. It instead employs an internal transmission range sensor.

This special sensor system utilizes a series of four contacts to confirm which gear the transmission is in. Whenever your car is not in park or neutral, this system prevents it from starting. However, it can eventually wear out and prevent your Jeep from starting under normal circumstances.

Shift your automatic transmission vehicle to neutral and give a slight push to the shifter while your Jeep is parked. It is recommended that you regularly engage the shifter by applying sufficient pressure.

Check the wireless contact module

The wireless contact module of the early JK Jeep Wranglers allows keyless entry, functioning of the immobilizer, and starting of the vehicle. The key emits an electrostatic discharge when placed into the ignition. This makes the WCM go into a security shutdown and keep the engine from starting. But even if this problem occurs, your Jeep can be started with the help of a workaround placed for such a situation. But this also means that your WCM is faulty and requires replacement.

If the security chip of your ignition key is faulty, your engine may start, but will soon die. A bad key has to be reprogrammed at the dealer. You should utilize a spare key in the meantime.

Check the starter

If your engine cranks but won’t start, there could be an issue with your starter. Starters can fail because of prolonged cranking resulting from impact damage or because of water ingestion. While it may not be possible to test the starter at the solenoid, the testing procedure can definitely be completed at the TIPM.

While the ignition key is on, remove the starter relay from the TIPM. use a digit multimeter or a test light to check for power at the terminal 30 or 87. If there is power at either terminal, use a fused jumper wire to jump them together. Your Jeep should be in park before you begin activating the starter. If your engine cranks in response, the starter is in good condition.

There could be other deeper reasons

There could be several reasons behind an engine not starting up. There could be defective cables or your fuel tank could be empty. This diagnosis should be left in the hands of the mechanics. We can only figure out the commonly occurring problems ourselves, only a professional can dive deeper and resolve the issue.


This situation generally arises when you least expect it. You step out in anticipation of a fantastic ride and your Jeep Wrangler doesn’t start. If your engine is still cracking, several reasons can be attributed to the occurrence of this problem. One of the commonest reasons is a failed battery. If it is a cold winter morning, this fault is even more likely to occur. You can thoroughly examine the functioning and charge of your battery to determine if it is the reason.

When you rule out the battery, examine the ground straps. Any corrosion or obstacle in these straps could block the proper flow of current in your Jeep’s engine and prevent it from starting. When this problem is also ruled out, check the safety switch. Primarily meant for your Jeep’s protection, this switch can itself become faulty at times and prevent it from starting.

Then analyze the wireless contact module and the starter. If all of these common reasons have been ruled out and your engine still doesn’t start, get your Jeep examined by a professional. There must be a deeper cause that needs repair. It is important that you carefully maintain your tough beast. Because however burly a vehicle may be, little things when left ignored can cause big troubles.


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