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.
2007 Hummer H3 L5-3.7LFACTORY OEM SERVICE PROCEDURE
Ignition System: Testing and Inspection
Electronic Ignition (EI) System Diagnosis
Circuit Description
The ignition system uses individual ignition coil/module assemblies for each cylinder. The powertrain control module (PCM) controls the individual coils by transmitting timing pulses on the ignition control (IC) circuit of each ignition coil/module to enable a spark event. The PCM monitors each IC circuit for improper voltage levels. Each ignition coil/module has the following circuits:
* An ignition voltage circuit
* A ground
* An IC circuit
Test
Step 1 - Step 10:
Step 11 - Step 14:
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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