Test 13 Thermactor Check (Code 45)

Fig.8 - MCU System Wiring Circuit:

1. Make sure that restrictor teed into the TAD vacuum line was uncapped and restrictor was free of contamination. If restrictor is okay, proceed to next step. If not, service restrictor as required.

2. Cap vacuum restrictor and remove vacuum delay valve from TAD vacuum control line. Reconnect system without delay valve and retest. If code 45 is obtained, proceed to the next step. If no code 45 is obtained, system is okay and delay valve is defective.

3. Remove vacuum hose from TAD valve and connect a vacuum gauge to hose. Start engine, increase speed to 2000 rpm and maintain for 2 minutes. Shut off engine, then restart to initiate self test while observing vacuum gauge. If vacuum pulses above and below 5 inches Hg, MC system is okay, check Thermactor pump output. If vacuum is always above 5 inches Hg, proceed to step 8. If vacuum is always below 5 inches Hg, proceed to next step.

4. Check solenoid vacuum hoses between TAD valve to TAD solenoid and between TAD solenoid and vacuum source for leaks or obstructions. If leaks or obstructions are found, correct as necessary. If not, proceed to next step.

5. Check TAD solenoid resistance. If resistance is within 50-110 ohms, proceed to next step. If not, replace solenoid.

6. Check for vacuum at TAD solenoid output when solenoid is energized by 12 volts. If there is vacuum, proceed to next step. If there is no vacuum, replace solenoid.

7. Check continuity at circuits 200 and 687 between MCU module and TAD for continuity using an ohmmeter. If resistance is greater than 5 ohms, replace MCU module. If resistance is less than 5 ohms, service the circuit.

8. Check that there is no vacuum at TAD solenoid output when solenoid is de-energized (harness disconnected, engine at idle). If there is vacuum, replace solenoid. If there is no vacuum, proceed to next step.

9. Check circuit 200 for short to ground using an ohmmeter, Fig. 8. If resistance is less than 1000 ohms, repair short. If resistance is greater than 1000 ohms, replace MCU module.