Jeep Grand Cherokee Won’t Start: Fixed!!

Jeep Grand Cherokee Won't Start

You hop into your Jeep Grand Cherokee, insert the key into the ignition, and turn…but nothing happens. Not even a click. The engine won’t turn over at all. Your Jeep Grand Cherokee suddenly won’t start.

This is incredibly frustrating, especially if you need to get somewhere in a hurry. A no-start condition can leave you stranded, making you late for work or other important engagements.

Why won’t your Jeep Grand Cherokee start? There are a number of potential culprits, from simple solutions like a dead battery to more complex issues like a failed starter motor.

In this troubleshooting guide, we’ll walk through the top 10 most common reasons a Jeep Grand Cherokee won’t start and how to diagnose and fix the issues yourself or with the help of a mechanic. We’ll cover:

Knowing the likely causes and solutions will help you quickly get your Jeep Grand Cherokee starting again. Let’s dive in!

Dead Battery – The Most Common Cause of a No Start

The number one reason your Jeep Grand Cherokee won’t start is a dead or dying battery. Your battery is crucial for providing the initial spark to start the engine.

Over time, batteries lose their ability to hold a charge due to chemical changes inside the battery. Hot weather also accelerates battery discharge. If your battery is more than 3-4 years old, it may simply not have enough remaining charge capacity to engage the starter.

Try jump starting the battery with cables and another vehicle. If the Jeep starts up with a jump, your battery is likely dead and needs to be replaced.

You can also try charging the current battery overnight with a trickle charger. However, if the battery is unable to hold a charge after charging, it means the battery is bad and should be replaced.

When replacing the battery, go with the manufacturer recommended battery for your Jeep’s engine size. The battery should be rated at 500+ cold cranking amps for sufficient starting power.

Make sure the battery terminals are clean and secure when installing the new battery. Keep the battery posts coated with dielectric grease to prevent corrosion.

With a fresh new battery installed, your Jeep Grand Cherokee should start right up when you turn the key. Make sure to drive regularly and go on longer trips to keep the new battery charged. Letting the battery discharge too low for extended periods will shorten its lifespan.

Loose or Corroded Battery Terminals

Before replacing the battery altogether, check the condition of the battery terminals. Loose battery cable connections or excessive corrosion on the battery terminals can prevent sufficient electrical current from reaching the starter motor.

Use a wrench to tighten the terminal connections if they are loose. Give them an extra quarter turn past hand tight. The connections need to be snug to minimize resistance.

If the terminals are corroded, clean them thoroughly with a wire brush or baking soda/water solution until you expose fresh metal. Scrape off any white, green or blue crusty buildup.

Apply dielectric grease or Vaseline to the terminals after cleaning to prevent corrosion reforming. Tighten the terminals down firmly and try starting the engine.

With clean, tightened connections, sufficient power should be able to flow to energize the starter.

Faulty Alternator Preventing Battery Recharge

Another related electrical issue that can cause a no start is an alternator that fails to recharge the battery while driving.

The alternator powers all of your Jeep’s electronics while also sending a charging current to the battery whenever the engine is running. Over time, the alternator wears out and can no longer provide a charging voltage.

When this happens, the battery gradually loses its charge as you drive until it has insufficient power left to start the engine.

To diagnose a bad alternator, use a multimeter to test the charging voltage while the engine is running. Turn on electrical loads like headlights, A/C, and stereo to put a draw on the charging system.

With loads on, measure the voltage at the battery terminals. It should show 13.5 to 14.5 volts if the alternator is charging properly. Any reading below 13 volts indicates a faulty alternator.

Replace the alternator if it is no longer supplying adequate charging current. Make sure to use an OEM part or quality remanufactured unit. Check that the new alternator provides 13+ volts before putting everything back together.

With a properly charging alternator, your battery will always have sufficient charge to start the Jeep.

Starter Motor Failure

The starter motor is responsible for turning over the engine when you turn the ignition key. Like any electromechanical component, the starter can wear out over the 100,000+ mile lifespan of a vehicle.

When a starter motor fails, you’ll hear silence or strange noises when turning the key instead of the typical cranking sound. Here are some clues your starter is bad:

  • Clicking sound but no cranking – A single click when the key is turned points to a starter solenoid failure. This relay sends voltage to the starter when energized.
  • Grinding noise – Pinion gear damage can prevent the starter drive from properly engaging the flywheel. This manifests as a grinding sound.
  • Chattering – If you hear rapid chattering or a whining noise, the bearings inside the starter motor could be worn out.
  • Partial cranking – Weak cranking that fails to start the engine indicates an armature or field coil winding is damaged.

Any of these symptoms likely mean it’s time to replace the starter motor. In some cases, you can remove the starter and have it rebuilt rather than replaced. But generally, it’s more cost effective to swap in a new starter.

When installing a new starter, make sure all connections are clean and secured. Shims may be required to adjust the starter mounting position. Road test to confirm normal cranking.

With a fresh starter that cranks properly, your Jeep Grand Cherokee will start with no problem.

Driving Until Empty – Rare But Possible

Before you assume engine issues are to blame, check first to make sure you actually have gas in the tank!

It sounds obvious, but running the tank bone dry is an easy mistake to make in modern vehicles. Fuel gauges can be inaccurate and suddenly indicate empty when there’s still a gallon or two left.

This “reserved” gas doesn’t get used until the gauge reaches E. If you keep driving beyond the gas light coming on, you could use up this last bit of gasoline.

With the tank completely empty, fuel can’t reach the engine and it will fail to start. Simply adding some gas should remedy the no start situation. Use the trip odometer to keep better track of actual mileage driven.

A Clogged Fuel Filter Can Prevent Starting

Another fuel related issue that could cause a no start is a clogged fuel filter. This small filter sits in the fuel delivery line to screen out dirt and debris before the fuel reaches the injectors.

Over thousands of miles, contaminants accumulate in the filter media. This causes restricted fuel flow to the engine.

Signs your fuel filter is due for replacement:

  • Hard starting or stalling after starting
  • Decrease in engine performance
  • Fuel pump makes whining noise from working harder

These symptoms indicate insufficient fuel pressure and volume being delivered to the engine.

If the filter is severely clogged, it can prevent starting altogether. No or little fuel reaches the cylinders.

Replacing the fuel filter every 30,000 miles ensures optimal fuel pressure and delivery. Use a filter wrench to avoid spilling fuel. Double check connections for leaks.

The fresh filter will restore normal fuel flow and your Jeep should start and run smoothly again. Consider keeping a spare filter on hand for emergencies.

When Fuel Pumps Fail?

The fuel pump is responsible for drawing fuel from the tank and delivering it to the engine at high pressure. Without the pump working properly, the fuel supply to the cylinders will be interrupted.

Mechanical fuel pumps have a diaphragm that moves fuel through the pump. After 100,000+ miles, the diaphragm can fatigue and develop tears or holes. This allows fuel to leak back down causing a loss of pressure.

Signs of a failing fuel pump:

  • Long cranking before starting – Weak pump has low pressure
  • Sputtering or stalling – Pump can’t supply enough volume
  • Whining noise from pump – Common when failing
  • Lack of fuel pressure at the rail – Direct indication

You can measure fuel pressure at the Schrader valve port on the fuel rail. Pressure should be 48-55 psi with the engine off. Any lower points to insufficient pump output.

Electrical fuel pumps will also eventually fail. These pumps are energized by a relay when the key is on. Listen for a humming noise from the tank when turning the key. No noise indicates no power to the pump.

Check for voltage at the pump electrical connector before condemning the pump itself. No voltage means the relay, wiring, fuse or inertia switch need diagnosis.

If the pump has power but low pressure output, it will need to be replaced. Match OEM specifications for flow rate and pressure.

With fuel pump operation restored, the no start condition caused by fuel delivery issues will be solved. Proper maintenance prevents premature fuel pump failure.

Crankshaft Position Sensor Failure

The crankshaft position sensor is a key input sensor that the powertrain control module relies on to deliver the proper air/fuel mixture and ignition spark timing.

This sensor monitors the position and speed of the crankshaft as it rotates. Data from the sensor allows the PCM to determine piston position and sync timing.

When the crank position sensor fails, the engine loses its primary feedback mechanism. This will prevent fuel injector pulses and spark ignition signals. Without properly timed fuel and spark, the engine won’t start.

Some common symptoms of a bad crank sensor:

  • No cranking when turning key – Starter won’t engage
  • Long cranking time to start – Timing is off
  • Stalling shortly after starting – Loses sync as RPMs drop

Scan for diagnostic trouble codes to help confirm crankshaft position sensor failure. “Crankshaft Position Sensor Circuit” and “Crankshaft Position System Variation Not Learned” codes point to sensor issues.

Access the crank sensor by removing plastic shrouding under the truck. Unplug the electrical connector and remove the mounting bolts. Install the new OEM sensor and clear codes. Test drive to confirm normal operation is restored.

Camshaft Position Sensor Problems

The camshaft position sensor serves a similar purpose to the crank sensor. It monitors the timing of the camshaft as it rotates.

This data on valve timing allows the PCM to properly synchronize the opening/closing of the intake and exhaust valves with the injector and ignition firing sequence.

When the cam sensor stops providing an accurate signal, the fuel/timing calibration will be thrown off. This can prevent the engine from starting or cause immediate stalling.

Cam sensor trouble codes include:

  • P0340 – Camshaft Position Sensor Circuit
  • P0343 – Camshaft Position Sensor Intermittent

As cam sensors fail, you may notice issues like:

  • Long cranking time
  • Rough idle
  • Engine misfires
  • Stalling, especially when cold

Since the cam sensor mounts at the front of the engine, valve cover removal is often required for replacement. Compare old and new sensor resistance values. Clear codes and verify normal operation after installing the new camshaft position sensor.

Security Lockout Preventing Fuel or Spark

One last possibility to check if your Jeep Grand Cherokee suddenly won’t start is the security system locking out engine functions.

Jeeps have an electronic Sentry Key security system that disables the fuel pump or ignition system if an invalid key is used or there’s theft attempt.

When the security light flashes quickly, this indicates the system has entered lockout mode. Fuel and/or spark will be blocked for up to 10 minutes until the system resets.

Lockout mode can sometimes falsely trigger from weak battery voltage or electrical “noise”. To reset the system:

  1. Turn the ignition key to ON (not Start)
  2. Wait 10 minutes until security light stops flashing
  3. Turn key OFF then attempt to start the engine

This allows the system to clear and restore fuel/ignition function. Make sure you are using the correct properly coded key. Replace the battery in the key fob if it’s weak.

If the security system keeps entering lockout mode, there may be an underlying fault needing diagnosis by the dealer. But in most cases, just waiting out the 10 minute reset enables starting again.

In Summary

Difficulty starting your Jeep Grand Cherokee can stem from a number of issues, but the problem is usually something on this list of the top 10 most common causes:

  • Dead battery
  • Loose or corroded battery terminals
  • Faulty alternator
  • Worn out starter motor
  • Empty gas tank
  • Clogged fuel filter
  • Failing fuel pump
  • Failed crankshaft position sensor
  • Faulty camshaft position sensor
  • Security system lockout

Methodically checking each of these potential culprits can quickly lead you to the root cause of the no start.

Often, the problem ends up being something simple like a dead battery or loose cable connection. But don’t overlook more complex issues like sensor failures which can also leave you stranded.

Equipped with this troubleshooting guide, you now have the key facts needed to diagnose why your Jeep Grand Cherokee won’t start. Let us know in the comments below if you found these tips helpful or have your own experience getting a no start Jeep running again!

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