Trace the wire from the combination switch to the main wiring harness connector and disconnect the connectors. Using an ohmmeter or self-powered test light along with the accompanying diagrams, check for continuity between the indicated switch terminals with the switch in each of the indicated positions. If the continuity isn't as specified, replace the switch. Disconnect the cable from the negative terminal of the battery, ensuring that if the stereo is equipped with an anti-theft system, the correct activation code is available before disconnecting. Remove the steering wheel, then the steering column covers. Unplug the electrical connectors from the combination switch, remove the retaining screws, and pull the combination switch from the shaft. Individual switches can now be removed from the switch body and replaced as necessary by detaching the retaining screws or pins and removing the defective switch. Installation is the reverse of removal.