Q: What are the primary checks for the ignition coil/igniter units used on Toyota Avalon and Toyota Solara?
A: Primary and secondary resistance checks for ignition coil/Igniter units on some Toyota and Lexus models don't apply to newer ones. The only test is to substitute a known good unit, which isn't practical for home mechanics. If all other ignition malfunction causes are ruled out, a faulty ignition coil/igniter unit is likely. To check primary resistance on some models, disconnect the electrical harness connector(s) from each coil and use an ohmmeter across the coil primary terminals. For secondary resistance, detach and label the spark plug wires from each coil and use an ohmmeter across the two secondary terminals. If resistance readings are off, replace the coil. When replacing, disconnect the battery's negative cable and follow specific removal and installation procedures for four-cylinder or V6 models.
Q: How do I disconnect the cable from the negative battery terminal and access the ignition coils on Toyota Camry and Toyota Avalon?
A: To disconnect the cable from the negative battery terminal, start by removing the engine cover on 2009 and earlier models by taking off the mounting fasteners and lifting it off. On 2010 and later models, lift the engine cover up from the rear and then the front, removing it from the mounting pins. For V6 engines, pry the engine cover up from the rear and remove it from the mounting pins. To access the rear ignition coils, remove the upper intake manifold. Each ignition coil/igniter assembly is secured by one bolt, so unscrew the bolt, disconnect the electrical connector, and pull the coil/igniter assembly straight up using a twisting motion. The individual ignition coil boot directly mounts over each spark plug. Installation is the reverse of removal.