High Altitude Switch
- Locate the high altitude switch on left instrument panel. Disconnect the altitude switch plug. Connect an ohmmeter to switch terminals. The altitude switch should be open under 3300 ft. (1000 m).
- Warm engine to operating temperature. Disconnect the oxygen sensor. Disconnect the high altitude switch. Remove vacuum hose from the fuel pressure regulator and plug.
- Connect an exhaust gas analyzer to the exhaust pipe. Operate engine at 2000 RPM and note CO% level.
- Bridge the high altitude switch harness terminals. At 2000 RPM, CO% level should be leaner. If not, check high altitude connectors. Ensure continuity of one wire to ground. The other wire should have continuity to CU terminal 28.