🔧 Grand Cherokee - Ignition Coil Replacement

Your Grand Cherokee is a diesel (3.0L turbo), so it does not use ignition coils or spark plugs like a gasoline engine. Instead, it uses glow plugs (small electric heaters that help cold starting) and high-pressure fuel injection.

Before I lay out exact steps: are you trying to replace glow plugs, or did you mean a different part?

Difficulty Level: Intermediate | Estimated Time: 1.5-4.0 hours

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⚠️ Safety & Precautions

• ⚠️ Let the engine cool fully; hot diesel components can burn you.
• ⚠️ Disconnect the negative battery cable to prevent electrical shorts at the glow plug harness/control system.
• ⚠️ Glow plugs can seize in the cylinder head; forcing them can break them.
• ⚠️ Wear eye protection; debris can fall when working around the intake area.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• 1/4" drive ratchet
• 3/8" drive ratchet
• 1/4" drive extension set
• 3/8" drive extension set
• Torque wrench (5–30 Nm range)
• 10mm socket
• 8mm socket
• Glow plug deep socket (10mm) (specialty)
• Trim clip removal tool
• Flat-blade screwdriver
• Needle-nose pliers
• Flashlight
• Compressed air blow gun

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Glow plug(s) - Replace all six recommended - Qty: 6
• Dielectric grease - Qty: 1
• High-temp ceramic lubricant (glow plug safe) - Qty: 1

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📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Open the hood and let the engine cool completely.
• Disconnect the battery negative cable using a 10mm socket and move it aside so it can’t spring back.
• If you have a scan tool, write down any stored codes first (common glow plug codes start with P0671–P0676).

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Confirm you’re not chasing “ignition coils”

• On a diesel, there are no ignition coils. If your symptom is hard starting (especially cold), rough idle when cold, or a glow plug code, continue below.
• If your symptom is loss of power, smoke, or fuel-pressure codes, stop here—those are usually not glow plug related.

Step 2: Remove the engine cover (if equipped)

• Use a trim clip removal tool (a plastic pry tool that lifts clips without breaking them) to release any retaining clips.
• Lift the cover straight up by hand. Use a flashlight to locate all attachment points first.

Step 3: Create access to the glow plug connectors

• Loosen any intake hose clamps with a flat-blade screwdriver (or use an 8mm socket if the clamp uses a hex head).
• Move the intake ducting/resonator out of the way enough to reach the glow plug electrical connectors along the cylinder heads.
• Take a photo before unplugging anything.

Step 4: Clean around each glow plug before removal

• Use compressed air blow gun to blow dirt away from the base of each glow plug so nothing falls into the area during removal.

Step 5: Unplug the glow plug electrical connector

• Use needle-nose pliers gently if needed, but do not crush the connector.
• Pull the connector straight off the glow plug terminal.
• Apply a tiny amount of dielectric grease to the inside of the connector boot for reassembly (don’t fill it).

Step 6: Remove the glow plug

• Use a glow plug deep socket (10mm) (specialty) with a 1/4" drive ratchet and the shortest extension that fits.
• Turn counterclockwise slowly. If it feels like it’s binding hard, stop and work it back and forth gently.
• Slow and steady prevents glow plug breakage.

Step 7: Install the new glow plug

• Start threading by hand first using the glow plug deep socket (10mm) with only an extension (no ratchet) to avoid cross-threading.
• If you use lubricant, apply a very light film of high-temp ceramic lubricant (glow plug safe) to the threads only (keep it off the tip).
• Tighten using a torque wrench (5–30 Nm range): Torque to 15 Nm (11 ft-lbs).

Step 8: Reconnect wiring and reassemble intake ducting

• Push the glow plug connector on until it seats firmly by hand.
• Reinstall intake ducting and tighten clamps using an 8mm socket or flat-blade screwdriver (whichever matches your clamps).
• Reinstall the engine cover by pressing it into place; reinstall any clips using the trim clip removal tool to align them first.

Step 9: Reconnect the battery

• Reconnect the negative battery cable using a 10mm socket.

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✅ After Repair

• Start the engine and verify it starts normally (especially from cold).
• If the check engine light was on, clear codes with a scan tool and recheck for returning codes after a short drive.
• Recheck that all intake clamps are tight and there are no hissing air leaks.

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💰 DIY vs Shop Cost

Shop Cost: $600-$1,200 (parts + labor)

DIY Cost: $120-$300 (parts only)

You Save: $480-$900 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-4.0 hours.

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🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.

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Quick questions (pick one):

• 🧾 Do you have any trouble codes (like P0671–P0676), or is this preventive maintenance?
• ❄️ Is the issue mainly on cold starts (hard start/rough idle for 30–60 seconds)?