🔧 RX350 - Starter Motor Replacement

On your RX350, the starter motor is mounted on the transmission side of the engine and is accessed mostly from underneath. The job is mainly removing undercovers, disconnecting the starter wiring, unbolting the starter, and reinstalling everything with the correct torque.

Difficulty Level: Intermediate | Estimated Time: 2-4 hours

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⚠️ Safety & Precautions

• 🛑 Disconnect the negative battery cable before touching the starter wiring (the main starter cable is always hot).
• 🛑 Support the RX350 with jack stands on solid, level ground; never rely on a floor jack alone.
• 🛑 Let the exhaust cool fully; the starter sits near hot components.
• 🛑 Keep the key fob away from the vehicle while working to prevent accidental electrical wake-up.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Mechanic gloves
• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• 10mm socket
• 12mm socket
• 14mm socket
• 3/8" drive ratchet
• 3/8" drive torque wrench (10-80 ft-lbs range)
• 6" extension (3/8" drive)
• 12" extension (3/8" drive)
• Universal joint adapter (3/8" drive)
• Trim clip remover
• Flathead screwdriver
• Needle-nose pliers
• Shop light
• Paint marker

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Starter motor assembly - Qty: 1
• Starter electrical terminal nut (if damaged) - Qty: 1
• Starter wire terminal boot (if torn) - Qty: 1
• Lower engine undercover fastener clips (as needed) - Qty: 4-10

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📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Chock the rear wheels using wheel chocks.
• Open the hood and disconnect the battery negative terminal using a 10mm socket. Tuck the cable aside so it can’t spring back. Prevents accidental short circuits.
• Raise the front of the RX350 using a floor jack and support it securely on jack stands.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the lower engine undercovers

• Use a trim clip remover and flathead screwdriver to pop out the plastic clips.
• Use a 10mm socket to remove any 10mm bolts holding the undercovers.
• Set all clips/bolts aside in a small container so nothing gets lost.

Step 2: Locate the starter and identify the electrical connections

• Use a shop light to find the starter on the transmission side of the engine.
• You’ll see:
• The large battery cable on the starter “B+” terminal (thick wire with a nut).
• The smaller starter control connector (plug-in connector).
• Take a quick photo before disassembly.

Step 3: Disconnect the starter electrical connector and main cable

• Remove the rubber boot from the large starter terminal using needle-nose pliers gently (don’t tear it).
• Use a 12mm socket to remove the nut on the main starter cable terminal.
• Lift the cable off and position it away from the starter stud.
• Disconnect the small control connector by pressing the tab and pulling straight off (use a flathead screwdriver carefully if the tab is stubborn).

Step 4: Remove the starter mounting bolts

• Use a 14mm socket with a 3/8" ratchet, plus a 6" extension and universal joint adapter as needed to access the bolts.
• Remove the starter mounting bolts (typically 2 bolts). Support the starter with your free hand as the last bolt comes out.
• Starter is heavier than it looks.

Step 5: Remove the starter from the vehicle

• Wiggle the starter free and lower it out from underneath.
• If it’s stuck, use a flathead screwdriver to gently pry at the mounting flange (do not pry on thin aluminum parts).

Step 6: Install the new starter

• Compare the old and new starter (same mounting ears and same electrical studs).
• Position the new starter and start the mounting bolts by hand to avoid cross-threading.
• Tighten the mounting bolts using a 14mm socket and 3/8" ratchet, then final-tighten with a 3/8" torque wrench.
• Torque to 39 Nm (29 ft-lbs) for the starter mounting bolts.

Step 7: Reconnect the starter wiring

• Reinstall the small control connector by pushing it on until it clicks.
• Install the main battery cable terminal on the starter stud and thread the nut by hand.
• Tighten the nut using a 12mm socket and torque wrench.
• Torque to 9 Nm (80 in-lbs) for the starter terminal nut.
• Reinstall the rubber boot over the terminal.

Step 8: Reinstall undercovers and lower the vehicle

• Reinstall the undercovers using the 10mm socket and plastic clips with the trim clip remover.
• Raise the RX350 slightly with the floor jack, remove jack stands, and lower the vehicle.

Step 9: Reconnect the battery

• Reconnect the negative battery terminal using a 10mm socket.
• Snug it firmly (do not overtighten the clamp).
• If clocks reset, that’s normal.

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✅ After Repair

• Start the RX350 and confirm it cranks strongly and starts normally.
• Listen for abnormal grinding or whining during cranking; if present, shut off and recheck starter seating and bolt tightness.
• Check that the starter cable boot is fully covering the terminal (helps prevent corrosion and accidental shorts).
• Verify no warning lights related to low voltage appear after startup.

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💰 DIY vs Shop Cost

Shop Cost: $650-$1,100 (parts + labor)

DIY Cost: $220-$450 (parts only)

You Save: $430-$650 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2-4 hours.

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