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OBD Code P0358 on 2003 GMC Sierra 1500: Diagnosis After Replacing All Ignition Coils

Model: 2003 GMC Sierra 1500 Fault Code: P0358 Posted: 2018-06-30 16:15

I recently replaced all ignition coils in my 2003 GMC Sierra 1500, but the vehicle is still displaying OBD code P0358. I am not experiencing any backfiring or misfires, and the coil connectors are securely locked with no visible damage or loose wires. Despite this, the fault persists. What could be causing this issue? I have a scan tool and can access freeze frame data if needed. The engine is a 4.8L MFI OVH, and all coils were aftermarket — not sourced from GM. I suspect the problem may lie in the coil control circuit or wiring specific to cylinder 8.

Related fault codes
P0358
Comments (10)
Anonymous 2018-06-30 17:20

Check the freeze frame data and try to recreate the fault condition. Did you use an OEM GM ignition coil? This can help isolate whether the issue is with the coil itself or elsewhere in the circuit.

Anonymous 2018-06-30 17:25

Verify the coil connector pinout — ensure correct wiring and connections are being used when testing. Always test using a multimeter set to ohms (AC scale) for continuity checks.

Anonymous 2018-06-30 18:41

When inspecting the connector, what should the expected reading be? I didn’t get full attachment during my inspection — could this affect performance?

Anonymous 2018-07-01 06:04

What is the engine displacement and type? A 4.8L MFI OVH engine has specific ignition circuit requirements that may influence fault diagnosis.

Anonymous 2018-07-01 07:30

You should perform a full wiring test on cylinder number 8. Do you have an ohmmeter or voltmeter? These tools are essential for diagnosing control signal and power circuits.

Anonymous 2018-07-01 18:53

I don’t currently own a multimeter, but I plan to purchase one by Monday. The engine is a 4.8L MFI OVH. I did not buy the coils from GM — all were aftermarket replacements.

Anonymous 2018-07-02 04:18

It's unlikely that an aftermarket coil is causing this issue, as I replaced all coils with after-market units and only cylinder 8 shows code P0358.

Anonymous 2018-07-02 04:54

What was the original fault code before replacing all ignition coils? Why were all coils replaced? Do you have a scan tool or OBD2 code reader available?

Anonymous 2018-07-02 05:05

I’ve owned this vehicle since 2003 and had no prior coil replacements. The initial fault was P0358, and I used a scan tool to confirm the issue.

Anonymous 2018-07-02 05:57

Testing the coil control circuit is limited due to shared wiring among cylinders. Most ignition coils share three wires (power, ground, and chassis ground), with only the control wire being unique — this is the purple wire for cylinder 8, which changes to purple/white at the connector. To verify signal activity, a lab scope or frequency meter would be needed. A tachometer or dwell meter should detect pulse activity if the circuit is active. Perform a short-to-ground and open-circuit test on the control wire from coil connector to PCM. Inspect PCM connector pins for damage and check coil terminal integrity. Clear codes before testing for signal presence. If you're unfamiliar with resistance tests, I can walk through them step-by-step. If wiring and connectors are intact and no control signal is detected, a faulty PCM may be the issue — though this is rare since the driver circuit resides inside the coil unit. Does the code return immediately after clearing? I’d recommend first verifying voltage feed and ground circuits using a multimeter (battery negative as reference).