Overboost Switch: Testing and Inspection

Fig. 18 Turbocharging System.:

Fig. 20 Pressure Switch Testing.:

1. Turn ignition switch to On position.
2. Disconnect hose from pressure switch Fig. 20.

Fig. 21 Applying Air Pressure To Pressure Switch.:

3. Connect tool 49H080740 or equivalent.Fig. 21
4. Adjust compressed air pressure to 10.4-11.6 psi.
5. If warning buzzer does not sound while applying compressed air, inspect voltage as follows:

Fig. 23 Pressure Switch Voltage Chart.:

a. Turn ignition switch to On position.
b. Apply air pressure of 10.4-11.6 psi to pressure switch and check voltage at Lg and B terminals with connector connected Fig. 23.
6. If voltages were not as described, inspect continuity of pressure switch as follows:

Fig. 22 Testing Pressure Switch With Ohmmeter.:

a. Turn ignition switch off.
b. Disconnect pressure switch connector and connect ohmmeter Fig. 22.

Fig. 24 Pressure Switch Continuity Chart.:

c. Apply air pressure of 10.4-11.6 psi to pressure switch and check continuity between terminals Fig. 24.
d. If continuity is no good replace switch.