System Testing

Fig 1: Lighting Interval for ECC Check On Pickup models, Red lamp should be on.

Disconnect the battery ground cable. Disconnect the exhaust gas sensor harness connector. Connect the terminal for exhaust gas sensor to ground with a jumper wire. Disconnect ECC 10-pin and 20-pin harness connectors from control unit.
Connect ohmmeter positive lead to terminal 4 and negative lead to body ground. With transmission in Neutral or Park, there should be zero ohms. In any other position, resistance should be infinity. See Fig 2 . If okay, neutral/park switch circuit is okay.
Shift lever to any position except Neutral. Connect ohmmeter positive lead to terminal 4 and negative lead to body ground. With clutch depressed, there should be zero ohms. With clutch released, resistance should be infinity. If okay, clutch switch circuit is okay.
Connect ohmmeter positive lead to terminal 6 and negative lead to body ground. With throttle depressed, there should be zero ohms. With throttle released, resistance should be infinity. If okay, throttle valve switch circuit is okay. If not, adjust the throttle valve switch.
Disconnect vacuum hose from vacuum switch for full throttle and connect vacuum pump. Connect ohmmeter positive lead to terminal 7 and negative lead to body ground. With a vacuum of below 4.72 in. Hg applied, resistance should be zero. With vacuum of above 4.72 in. Hg applied, resistance should be infinity. If okay, vacuum switch circuit is okay.
Connect ohmmeter positive lead to terminal 8 and negative lead to terminal 16. With water temperature above 68°F (20°C), resistance should be below 2900 ohms. With water temperature below 68°F (20°C), resistance should be 2100 ohms or above. If okay, water temperature sensor and circuit is okay. If not, go to next step.

Dip the water temperature sensor into water maintained at a temperature of 68°F (20°C). Resistance should be 2100-2900 ohms. At 122°F (50°C), resistance should be 680-1000 ohms. If okay, repair or replace ECC harness. If not okay, replace water temperature sensor.

Fig 2: Internal View of Terminal Locations for ECC Connectors

SOLENOID RESISTANCE SPECIFICATIONS

Application	Ohms
Mixture Heater	60-85
Air-Fuel Ratio	30-50
Richer Solenoid	20-40
Anti-Dieseling Solenoid	25-45
Air Injection	25-45
Idle Speed Control Solenoid	25-45

SOLENOID & RELAY CHECK TERMINAL IDENTIFICATION

Application	Check Terminal
Mixture Heater Relay	3
Air-Fuel Ratio Solenoid	F
Richer Solenoid	B
Anti-Dieseling Solenoid	G
Air Injection Solenoid	H
Idle Speed Control Solenoid	I

Connect ohmmeter positive lead to terminal 2 and negative lead to body ground. Resistance should be zero ohms. If okay, exhaust gas sensor circuit is okay.
Connect ohmmeter negative lead to body ground and positive lead to first terminal A and then terminal E. Resistance should be zero. If okay, ground circuits are okay. If not, check harness.
On vehicles with Z24 engine, connect voltmeter positive lead to terminal B and negative lead to body ground. With ignition switch in the "ON" position, pointer should deflect. If okay, spark plug switch control is okay. If not, check harness and ignition control unit.
Connect voltmeter positive lead to terminal C and negative lead to body ground. Disconnect alternator L terminal. With ignition switch in the "ON" position, battery should be present. If okay, mixture heater circuit is okay. If not, check wire harness, auto choke relay and mixture heater relay.
Connect voltmeter positive lead to terminal D and negative lead to body ground. With ignition switch in the "START" position, pointer should deflect. If okay, trigger input to the control unit is okay. If not, check ignition coil and wire harness.
Connect voltmeter positive lead to terminal F and negative lead to body ground. With ignition on, battery voltage should be present. If okay, air fuel-ratio control solenoid circuit is okay.
Connect voltmeter positive lead to terminal G and negative lead to body ground. With ignition on, battery voltage should be present. If okay, anti-dieseling solenoid circuit is okay.
Connect voltmeter positive lead to terminal H and negative lead to body ground. With ignition on, battery voltage should be present. If okay, battery source circuit is okay.
Connect voltmeter positive lead to terminal I and negative lead to body ground. With ignition and A/C on, battery voltage should be present. If okay, FICD circuit is okay.