Test Point 14 - Altitude Correction Box

1. Connect CO meter to test connector ahead of catalytic converter.
2. Disconnect altitude correction box under drivers seat and observe CO meter.

Reading changed, replace altitude correction box. End of test.
Reading did not change, proceed to next step.

3. Using a test wire, jumper correction box harness connector.
4. Observe CO meter.

Value lowered by 0.5 - 1%, proceed to next step.
Reading did not change, check wiring. If wiring and all applicable test points check OK, replace DME control unit.

5. Connect ohmmeter across altitude correction box terminals.

Open, below 3000 ft, altitude correction box OK. End of test.
Not open, below 3000 ft, replace altitude correction box.