Models Produced From March 1990
IDLE SWITCH CHECKIdle switch should close when throttle lever is between 0.012" - 0.016" (0.3mm - 0.4mm) off idle.
1. Disconnect two terminal idle switch harness connector.
2. With throttle closed, insert a 0.012" (0.3mm) feeler gauge between the throttle lever and idle stop adjustment screw and check continuity between terminals on switch side of connector.
^ Should have continuity (switch closed).
If not, remove throttle body and loosen mounting screws and rotate potentiometer assembly (in the same direction as the throttle valve opens) just as much as is necessary to obtain continuity through the idle switch and tighten screws. If continuity cannot be obtained by adjustment, replace throttle switch/potentiometer assembly.
3. Insert a 0.016" (0.4mm) feeler gauge.
^ Should have no continuity (switch open).
If not OK, open throttle by hand.
^ Should have no continuity (switch open).
If OK, re-adjust idle switch.
If not OK, replace throttle valve potentiometer assembly.
POTENTIOMETER CHECK
Throttle Valve Potentiometer And Connector Terminal ID:
1. Disconnect harness connector from potentiometer.
2. Check resistance between potentiometer terminals #1 and #2.
^ Should be between 1,500-2,600 ohms.
If not, replace potentiometer assembly.
3. Check resistance between potentiometer terminals #2 and #3.
^ Should be between 750-1,300 ohms.
If not, replace potentiometer assembly.
4. Slowly open throttle.
^ Resistance should increase smoothly as throttle is opened. When throttle is fully open, resistance should be not more than 3,600 ohms.
If any measured resistance is not within the specified range, replace potentiometer assembly.
SUPPLY VOLTAGE AND CIRCUIT CONTINUITY CHECK
1. Leave potentiometer harness connector disconnected.
2. Connect DVM between harness connector terminals #1 and #2.
3. Turn ignition ON and note voltage.
^ Voltage should be approx. 5 volts.
4. Check voltage between harness connector terminals #1 and #3.
^ Voltage should be approx. 5 volts.
If either voltage value is not obtained, check for:
a. Open or grounded circuit between harness connector (terminals #1, #2, & #3) and ECU (terminals 6A, 8A, and 7A respectively).
b. Open or grounded circuit between potentiometer harness connector terminal #2 and idle switch terminal #2 (Brn/Grn wire).
c. Open or grounded circuit between idle switch terminal #1 and ECU terminal 9A (Grn/Violet wire).
Make any necessary repairs and re-check.
If no wiring problems are found and there is no voltage reading in steps 3 or 4, or if voltage is greater than 5.5 volts, then the ECU is faulty.