Test 8: Upstream Solenoid Test
NOTE:
When applicable, diagnostic terminals can be used as test points instead of MCU connector terminals.
- Determine if manifold vacuum is supplied to port E of solenoid. If no, repair and proceed with test. If yes, turn ignition on. With voltmeter, test for battery voltage at solenoid Yellow wire terminal. If not okay, repair and proceed with test. If okay, turn ignition off. Disconnect MCU harness connector. Measure the resistance between MCU connector J2 pin 11 (positive probe) and MCU connector J2 pin 13 (minus probe).
- Resistance should be between 50-90 ohms. If not, go to step 5. If so, connect MCU harness connector and disconnect vacuum hose at port of solenoid. Start and warm engine for at least 4 minutes. Stop engine and disconnect WOT and thermal electric switch connectors. Stop engine and connect jumper wire from MCU connector J2 pin 6 to ground. Start engine and measure voltage at connector J1 pin 13 during the first 30 seconds of engine operation.
- If voltage is more than 3 volts, go to step 4. If voltage is less than 3 volts, wait 60 seconds and retest voltage. If battery voltage is not present, go to step 4. If battery voltage is present, turn engine off. Restart engine and check port D for vacuum. After 30 seconds, vacuum should disappear at port D. If not, replace upstream solenoid and retest. If vacuum is okay, test is complete. Solenoid is normal. Remove jumper wires and connect hoses.
- Test MCU harness connector J2 pin 11 for battery voltage. If not okay, repair and retest. If okay, test MCU connector J2 pin 1 for continuity to ground. If not okay, repair and retest. If okay, replace MCU and retest upstream solenoid.
- If resistance was less than 50 ohms, go to next step. If resistance was greater than 90 ohms, disconnect wire connector from solenoid using long jumper wire. Test continuity between solenoid (Pink wire) and MCU connector J1 pin 13. If okay, replace upstream solenoid and retest. If not, repair wire harness and retest.
- If less than 50 ohms, disconnect solenoid wire connector and remeasure resistance. If circuit is not open, locate and repair short circuit and retest. If circuit is open, replace solenoid and retest.