Component Diagnosis & Testing

1. Turn ignition switch and cruise control main switch to On position.
2. Ensure main switch indicator lamp illuminates. If lamp does not illuminate, check continuity between terminals of cruise control main switch, Fig. 16 through 19. If switch operates correctly, repair wire harness.

Fig. 16 Main Switch Test:

Fig. 17 Main Switch Test:

Fig. 18 Main Switch Test:

Fig. 19 Main Switch Test:

3. Measure voltage at following terminals of the control unit, Fig. 20 through 25. If terminal voltage are correct, replace cruise control unit.

Fig. 20 Cruise Control Unit Voltage Test:

Fig. 21 Cruse Control Unit Voltage Test:

Fig. 22 Cruise Control Unit Voltage Test (Part 1 Of 2):

Fig. 22 Cruise Control Unit Voltage Test (Part 2 Of 2):

Fig. 23 Cruise Control Unit Voltage Test (Part 1 Of 2):

Fig. 23 Cruise Control Unit Voltage Test (Part 2 Of 2):

Fig. 24 Cruise Control Unit Voltage Test:

Fig. 25 Cruise Control Unit Voltage Test (Part 1 Of 2):

Fig. 25 Cruise Control Unit Voltage Test (Part 2 Of 2):

4. Disconnect cruise stop lamp and clutch switches and ensure continuity exists between terminals only with pedal depressed.
5. If switches operate correctly, repair wiring to switches.
6. Check for continuity between terminals of cruise control switch, Fig. 26 through 29. If switch operates correctly, repair wire harness.

Fig. 26 Cruise Control Switch Test:

Fig. 27 Cruise Control Switch Test:

Fig. 28 Cruise Control Switch Test:

Fig. 29 Cruise Control Switch Test:

7. Disconnect stop lamp switch and ensure continuity exists between terminals only with pedal released.
8. Measure actuator solenoid resistance using an ohmmeter, Fig. 30 through 33. If continuity is not as specified, replace actuator.

Fig. 30 Actuator Operational Test:

Fig. 31 Actuator Operational Test:

Fig. 32 Actuator Operational Test:

Fig. 33 Actuator Operational Test:

9. If continuity is as specified, disconnect actuator cable, start engine and run at a idle.
10. Apply battery voltage to terminals shown in Fig. 34 through 36, and check actuator operation. If not as specified, replace actuator.

Fig. 34 Actuator Continuity Test:

Fig. 35 Actuator Continuity Test:

Fig. 36 Actuator Continuity Test:

11. Remove instrument cluster as described in appropriate chassis section.
12. Connect an ohmmeter between the following terminals on the 12-pin connector:
a. On Miata models, connect between terminals 2F and 2D.
b. On 1993-95 MPV models, connect between terminals 1J and 2A.
13. Ensure intermittent continuity between terminals while rotating speedometer cable shaft. If four times per rotation, replace speedometer.