Turbo Boost Sensor: Testing and Inspection

Checking the pressure transducer

Tools: Pressure gauge 83 93 514
Hose with connector (included with the pressure gauge)
Air pump (radiator tester)
Vacuum pump
Ohmmeter








1. a. Check the transducer by unplugging the connector from the APC control unit and measuring the resistance between terminal 9 (green/red; CN/RD) and terminal 8 (black; SV).

Note: To preclude damage to the connector, apply the rest prods to the same side as that on which the cables enter the connector.




Remove the gaiter from between the front and rear centre consoles. Remove the centre console.

b. Remove the lower section of the safety padding.




c. Disconnect the pressure transmitter hose at the Y connector. Connect the pressure gauge equipment to the hose from the pressure transducer.

As from 1986 models:
First, remove the cover from the electrical connector. Measure the resistance between terminal 23 (black/white; SV/VT) and terminal 10 (green/red; GN/RD).

Note: To preclude damage to the connector Y, apply the rest prods to the same side as that on which the cables enter the connector.

Note: Keep the pressure gauge vertical to avoid erroneous readings.




2. Connect the air pump via the hose and connector to the hose from the pressure transducer.




3. Disconnect the cables from the pressure transducer.




4. Connect an ohmmeter to the electrical terminals of the pressure switch.
Measure the resistance which should be 10 ohm (tolerance: - 5 ohm; + 3 ohm) at atmospheric pressure.







5. Using the air pump, raise the pressure to 1 bar (14.5 PSI) approx, then reduce it to 0.60 bar (8.3 PSI) while tapping the pressure transducer lightly with the handle of a screwdriver. Measure the resistance which should be 88 ± 5 ohm at 0.60 bar (8.3 PSI)

If the above readings are not obtained, or a short circuit or break in the circuit is indicated, replace the pressure transducer.

6. Replace the air pump with the vacuum pump and raise a vacuum of approx. 0.5 bar (6.6 PSI)

Check the resistance again for signs of a short circuit or break in the circuit.