HA4 - Check MAP/BARO Frequency

- Key "OFF".

- Connect Manifold Absolute Pressure (MAP)/Barometric Pressure (BARO) tester.

- Key "ON".

- Refer to MAP/BARO Frequency Charts to check MAP/BARO frequency. HA - MAP/BARO Sensor Barometric Pressure Graph

- It may be necessary to measure several known good MAP/BARO sensors on available vehicles to determine area's typical reading for that day.

- Is MAP/BARO frequency within specification?

Yes -- For vehicles with Multiport Fuel Injection (MFI): Go to HA5. HA5 - Diagnostic Test Mode (DTM): MFI Engines

All others: Go to HA6. HA6 - Diagnostic Test Mode (DTM): SFI Engines

No -- Check wiring to MAP/BARO sensor for corrosion, high resistance, etc. If OK, replace MAP/BARO sensor. Clear KAM. Clearing Keep Alive Memory (KAM) and Relearn Procedure

Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)