GMC 12048976 Harness Asm

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Begin this procedure by visually checking the spark plug wires while the engine is running. In a darkened garage with ventilation, start the engine and observe each plug wire for arcing or sparks at damaged areas. If arcing is noticed, obtain new wires and check the distributor cap and rotor after allowing the engine to cool. Disconnect the negative battery cable and remove the distributor cap by releasing the holddown latches. Inspect the cap for cracks and corrosion on the contacts, removing deposits with a file if necessary. Examine the rotor for cracks, burning, and carbon tracks, replacing it if needed. Apply silicone lubricant to the contact inside the cap before reinstalling the cap and rotor. If the cap needs replacement, leave it off with the wires still connected. If the spark plug wires need replacement, obtain a new set along with a new cap and rotor. Check each wire individually, inspecting for corrosion, crimping the metal connector if necessary, and cleaning the entire length of the wire. Bend the wires to ensure flexibility. Check the wires at the distributor cap, reinstalling them securely. If the wires, cap, and rotor are in good condition, reconnect them at the distributor and battery. If new wires are required, obtain them along with a new cap and rotor. If a new cap is being installed on a coil-in-cap distributor, transfer the coil and cover from the old cap to the new one. Attach the coil to the new cap with a new seal and lubricate it. Attach the rotor to the distributor, ensuring proper installation of the carbon brush in the cap. Replace the wires one at a time, maintaining the correct firing order. Reattach the cap to the distributor and reconnect all wires and the battery cable.

Any wire that shows a resistance over 30,000 ohms should be replaced.

Clean the entire length of the wire with a rag, removing dirt and grease, and inspect for burns, cracks, or other damage. Bend the wires to ensure the inside wire is still conductive.

Carefully remove the spark plug wire boots from the spark plugs by twisting and pulling on the boot, never directly on the wire.

For four-cylinder engines, you can disconnect the spark plug wire from the coil pack by pulling on the rubber boot. Always pull on the boot, not the wire.

To reattach the wire to the distributor cap, simply reattach it securely.

A visual check can be done in a darkened garage, observing each wire for arcing or sparks.

You can disconnect the plug wire from one spark plug by grabbing the rubber boot, twisting slightly, and pulling the wire free.

Four-cylinder engines usually have a distributor-less ignition system, with spark plug wires connected directly to the ignition coils. V6 engines, on the other hand, use a distributor mounted at the rear of the block.

Inside the boot of a spark plug wire, you should check for corrosion, which can appear as a white crusty powder. Ensure the boot fits securely onto the spark plug.

When inspecting the remaining spark plug wires, make sure that each one is securely fastened at the distributor and spark plug.

Clean the wire with a rag, removing dirt and grease, and inspect for burns, cracks, or other damage. Bend the wire in multiple places to check its flexibility.

For V6 engines, you can disconnect the spark plug wire from the distributor at the rear of the engine. Ensure a tight fit and replace the wire at the coil pack or distributor as needed.