Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2009 Jeep Liberty 4WD V6-3.7LFACTORY OEM SERVICE PROCEDURE
Ignition System: Description and Operation
DESCRIPTION
The ignition system is controlled by the Powertrain Control Module (PCM) on all engines.
This engine uses a separate ignition coil for each cylinder. The one-piece coil bolts directly to the cylinder head. Rubber boots seal the secondary terminal ends of the coils to the top of all 6 spark plugs. A separate electrical connector is used for each coil.
Because of coil design, spark plug cables (secondary cables) are not used. A distributor is not used with the 3.7L engine.
Two knock sensors (one for each cylinder bank) are used to help control spark knock.
The Auto Shutdown (ASD) relay provides battery voltage to each ignition coil.
The ignition system consists of:
- 6 Spark Plugs
- 6 Separate Ignition Coils
- 2 Knock Sensors
- Powertrain Control Module (PCM)
- Also to be considered part of the ignition system are certain inputs from the Crankshaft Position, Camshaft Position, 2 knock and MAP Sensors
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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