Troubleshooting Tips for When Your Jeep Grand Cherokee Won’t Start

Has your Jeep Grand Cherokee refused to start, leaving you stranded? A no-start condition can be incredibly frustrating, but don’t panic. In most cases, the cause is something simple that you can fix yourself with minimal tools and some troubleshooting.

In this comprehensive guide, we’ll walk through the most common reasons a Jeep Grand Cherokee won’t start and provide tips to get you up and running again. Whether your engine won’t turn over, struggles to start, or just makes clicking noises, we’ve got you covered.

Why Your Jeep Grand Cherokee Won’t Start?

There are a number of reasons why your Jeep Grand Cherokee may not start:

• Dead or weak battery – The most common cause for a no-start is a battery that can’t provide enough power to crank the engine.
• Faulty starter – If the starter motor is bad, your Jeep won’t crank or start.
• Ignition switch issues – Problems with the ignition switch or lock cylinder can prevent the engine from starting.
• Bad starter relay or solenoid – Issues with the starter relay or solenoid will affect the starter motor.
• Neutral safety switch failure – This switch prevents starting unless the transmission is in Park or Neutral.
• Faulty fuel pump – A bad fuel pump won’t be able to provide the necessary fuel pressure for starting.
• Crankshaft/Camshaft position sensor failure – These key sensors aren’t providing proper timing signals to the fuel and ignition systems.
• Bad spark plugs or ignition coils – Proper ignition spark is needed for combustion and starting.
• Out of fuel – Make sure you haven’t run the gas tank completely empty.

By methodically checking each of these possibilities, you can diagnose and fix the no-start issue. Let’s look at how to troubleshoot each scenario in more detail.

Step 1 – Check The Battery and Terminals

The battery is the first thing to check when diagnosing a no-start problem. Using a multimeter or battery tester, check the state of charge and voltage. Battery voltage should be 12.4 volts minimum when the Jeep is off, and shouldn’t drop below 10.5 volts during cranking.

If the battery fails the test or is more than 3-5 years old, it’s time for a replacement. The jeep grand cherokee’s large V8 engine requires a robust 12-volt battery to crank over.

Inspect the battery terminals and cables for corrosion, breaks, or loose connections. Clean terminals with a wire brush and baking soda solution. Tighten any loose clamps and replace damaged cables. Proper voltage must reach the starter at all times.

If the battery checks out ok, move on to testing the starter motor circuit itself.

Step 2 – Check The Starter

The starter is responsible for spinning the engine to get it running. When you turn the key to “Start”, voltage flows to the starter motor which engages the flywheel via the starter drive gear.

Problems with the starter can cause a no-crank situation when you try to start your Jeep. Listen for starter noise when turning the key. If you hear nothing, there is likely an open circuit. If you hear a click or rapid clicking, the issue is likely the starter solenoid or relay.

Use a multimeter to check voltage at the starter solenoid S terminal while trying to start. You should see 10+ volts indicating power is getting to the starter. If there is power but no cranking, the jeep starter motor itself has failed.

To check the solenoid, locate the two large terminals where the heavy battery cable connects. Check that 12+ volts is present there when turning the key. No voltage means the solenoid is bad and not engaging.

If the solenoid checks out, ensure the starter drive gear isn’t stuck. Turn the key briefly while listening for the gear to retract. Tap on the starter with a mallet to free up the gear. If problems persist, replacement of the entire starter assembly may be required.

Step 3 – Test The Ignition Switch

The ignition switch signals the starter relay to send power to the starter when you turn the key to “Start”. If your jeep cherokee’s lights and accessories work but you get no crank, the ignition switch should be tested.

Try tapping or jiggling the key while turning to “Start”. If the starter suddenly engages, it points to a faulty ignition switch. Insert the key and rotate back and forth rapidly to clean the switch contacts. If problems recur, the entire ignition cylinder may need replacement.

Use a multimeter to check for 12 volts at the starter relay when turning the key to “Start”. No voltage indicates an open circuit and likely a bad ignition switch. The switch will have to be replaced in this case.

Step 4 – Check The Starter Relay

The starter relay controls power to the starter solenoid when cranking. You’ll find this important relay within the junction box located under the dash. The relay has a control circuit and a high current output circuit.

With key in “On” position, use a multimeter to check if the relay control coil is getting 12 volts on the low current 85 terminal. Verify the relay is properly grounded. If voltage is present but relay doesn’t close, replace the faulty relay.

You can swap the starter relay with an identical known good relay as a quick test. If starter engages with the good relay, this confirms the original relay was bad. Make sure to use an identical relay to avoid damage.

Step 5 – Inspect The Neutral Safety Switch

The neutral safety switch (also called inhibitor switch) is a safety device that prevents cranking unless the transmission is in Park or Neutral. It requires proper adjustment in order to start.

Shift to neutral and try starting again. If the jeep starts in neutral but not Park, the issue is with the NSS or adjustment. Adjust the switch position or replace if faulty. Don’t override a faulty NSS, as this can lead to serious damage and accidents.

Step 6 – Check Spark Plugs And Ignition Components

For the engine to start, the spark plugs must emit a strong ignition spark at the proper interval. Weak or inconsistent sparks will lead to a no-start. Inspect the spark plugs for excessive wear and proper gap distance. Replace worn plugs using manufacturer specified parts.

The ignition coils convert low voltage to the very high voltage needed to jump the spark plug gap. If the coils are failing, they may intermittently provide spark. Remove coils one by one to isolate any faulty coils. Test coil primary and secondary resistance as per specifications. Replace any out-of-spec coils.

Connectors and wiring for the spark plugs and ignition coils should be carefully inspected for damage or corrosion. Any degradation can lead to ignition misfires and failure to start.

Step 7 – Verify Fuel Level and Fuel Pump Operation

It may seem obvious, but make sure you haven’t run the jeep’s gas tank completely dry. The fuel gauge can give false readings when very low on fuel. Visually check the tank level if needed and top up.

The fuel pump provides pressurized fuel for injection and combustion. When the key is turned on, you should hear the electric fuel pump operate for a few seconds as it pressurizes the system. No priming noise likely indicates pump failure.

Check the fuel pump fuse and relay. Use a multimeter to verify voltage at the pump connector when the key is on. No power indicates a blown fuse, faulty relay, or open circuit. Replacing the fuel pump will be required if it’s not operating.

A fuel pressure test gauge can definitively diagnose fuel pump issues. Connect the gauge and check that system pressure meets specifications. Consistently low or erratic pressure confirms pump failure.

Step 8 – Test The Crankshaft and Camshaft Sensors

The crankshaft position sensor and camshaft position sensor are key in establishing proper ignition timing for starting the engine. Issues with either sensor can lead to a no-start.

Carefully inspect each sensor and their wiring for damage. Check that the connectors are clean/dry. Unplug the sensors one by one and check the internal resistance with a multimeter as specified by the manufacturer. Out of range resistance indicates a defective sensor that must be replaced.

Since these sensors work in conjunction, replacing both at the same time is recommended if one is found faulty. Proper positioning of the sensors is also critical for accurate signals.

When to Seek Professional Help?

While many no-start issues can be resolved with basic tools and troubleshooting, there are times when it’s best to have a professional mechanic look at your Jeep. Here are some instances when you’ll want to seek expert assistance:

• You’ve checked all the ignition and fuel system components but the engine still won’t start or run properly. At this point there may be underlying electrical issues that require diagnosis.
• The starter cranks very slowly even with a good battery. This can indicate high current draw from a short circuit or seizing engine.
• You don’t have the proper tools or experience to safely troubleshoot components like the ignition coils, cam/crank sensors, etc. Improper testing can damage these parts.
• The no-start issue is intermittent and happens randomly. Intermittents are tricky to diagnose without workshop tools and skills.
• You need to source and replace hard-to-find electronic components like the PCM, cam sensor, etc. A mechanic can find genuine OEM replacement parts.
• There are other accompanying symptoms like rough running, loss of power, black smoke, warning lights, etc. The no-start may be a symptom of a larger mechanical or diagnostic issue.
• You’ve replaced the starter, battery and related components but the problem promptly returns. This indicates an underlying issue that was not properly addressed.

While frustrated when your Jeep won’t start, avoid taking shortcuts or throwing parts at the problem. In some cases it pays to have the experts handle complex diagnostics and repairs. This will get your Cherokee back on the road reliably and save you time and money in the long run.

Conclusion

Hopefully by now you’ve managed to get your Jeep Grand Cherokee starting and running properly again. Be patient and take a systematic approach to isolate the no-start cause. The battery, starter system, and fuel/ignition systems are key areas to focus your diagnosis and testing. Preventative maintenance will help maximize battery and starter life. Consider a complete replacement of the ignition components if several are faulty. Don’t hesitate to enlist a professional Jeep mechanic if needed, as they have specialized tools and expertise.

Follow the helpful troubleshooting tips provided in this article to get your engine cranking and roaring back to life. Driving a well-maintained Jeep Grand Cherokee is an absolute pleasure, so take care of any no-start issues promptly. Here’s to many more miles of happy and reliable Jeep journeys ahead!