Except 3.5L (VIN H) Engine
- Remove the ignition coil(s).
- Using an ohmmeter, check the resistance between the primary terminals on the underside of the coil. The resistance should be 0.50-0.90 ohms.
- Check the resistance between the secondary terminals. It should be 5,000-8,000 ohms.
- If the coil failed either test, replace the coil.
REMOVAL & INSTALLATION
Except 3.5L (VIN H) Engine
All of the vehicles covered by this guide use V6 engines and, with the exception of the 3.5L engine, similar ignition systems. The ignition coil removal procedures are similar, differing only in the types of wiring connections.
- Disconnect the negative battery cable.
- Note the position of the spark plug wires for installation. Numbered tags of masking tape or other identification will save time at installation. Spark plug wires MUST be returned to their original and proper locations. Unplug the spark plug wires from the ignition coils.
- Remove the 2 screws securing the each ignition coil to the ignition control module and remove the ignition coil(s).
- Position the ignition coil(s) to the ignition control module.
- Install the 2 retaining screws for each coil, then tighten to 40 inch lbs. (5 Nm).
- Attach the spark plugs wires as noted during removal.
- Connect the negative battery cable.
- Verify that the ignition switch is in the OFF position.
- Remove the engine cosmetic/acoustic shield (technically called the injector sight shield). Remove the two mounting nuts and then lift the cover off the mounting studs by lifting at the front of the cover.
- Unplug the ignition coil module electrical connector.
- Remove the seven ignition coil assembly (GM calls it the 'ignition cassette') to cam cover mounting bolts.
- Gently pry the cassette away from the cam cover using a screwdriver (protect the finished surfaces from scratches with a shop cloth). Pry a small amount in several locations around the edge of the cassette in order to lift the assembly as evenly as possible. Do not insert the screwdriver far enough to tear the perimeter seal on the cassette.
- On some vehicles, the oil level indicator (dipstick) tube may interfere with the removal of the front bank coil cassette. Remove the oil level indicator tube retaining bolt and move the oil tube, as necessary.
- Lift the coil cassette straight up off of the spark plugs.
- Remove the secondary boots from the spark plugs or the ignition coils, using a twisting motion to break the seal. Use tool J 43094 Spark Plug Boot Removal Tool or its equivalent. This is a long, padded gripping tool designed to reach down into the spark plug well to remove the boots. GM cautions against the use of pliers, screwdrivers or any unauthorized tool to remove the boots.
- Do not re-install any component that has visible signs of damage. Check the boots for a missing or damaged internal spring. Make sure the boots are installed right side up. Make sure the ignition cassette to cam cover ground spring is in places. If necessary, repair a torn perimeter seal with RTV sealant. Clean all mounting surfaces before re-installing components.
- Install the boots onto the ignition coils (until bottomed out).
- Install the cassette assembly straight down onto the spark plug boots. If this is not possible due to space limitations (rear bank), just start the boots onto the spark plugs and then align and start the ignition coil towers into the boots. Press the coil assembly as straight down onto the plugs as possible.
- Install the seven ignition cassette to cam cover mounting bolts and tighten to 84 inch lbs. (9.5 Nm).
- Plug in the ignition control module electrical connector.
- If the oil level indicator tube was moved during disassembly, move the tube back into position, then install the retaining bolt and tighten to 80 inch lbs. (9 Nm).
- Keeping the engine cosmetic/acoustic cover as level as possible, place the rear of the shield under the mounting bracket, and align and press the cover onto the mounting studs. Install the nuts and snug down to just 27 inch lbs. (3 Nm).