Diagnostic Aids

Perform this test when instructed by QUICK TEST or if directed by other test procedures. This test is only intended to diagnose:

CANP solenoid.
Harness circuits (CANP and VPWR).
ECA.

Fig 1: Canister Purge (CANP) Circuit

TEST PIN NO. 31 Or 11 (CANP) WIRE COLOR ID

Application	Wire Color
Probe 3.0L	White/Black
Except Probe 3.0L	Gray/Yellow

TEST PINS NO. 37 & 57 (VPWR) WIRE COLOR ID

Application	Wire Color
Probe 3.0L	Black/White
Except Probe 3.0L	Red

1) Check System Function Use only VOM or DVOM for this step. DO NOT use scan tester. Turn ignition off. Disconnect cruise control servo wiring harness connector. Connect DVOM negative lead to STO terminal at self-test connector. Connect positive lead to positive battery terminal. Install a jumper wire between STI terminal and SIG RTN terminal at self-test connector. See Figure - in CIRCUIT TEST B. Perform KOEO SELF-TEST until continuous memory test is complete. DVOM will read less than 1.0 volt when test is complete to indicate ECA has entered OUTPUT STATE CHECK. Depress and release throttle. If voltage increases, remain in OUTPUT STATE CHECK and go to step 2). If voltage does not increase, depress throttle to WOT and release. If STO voltage does not increase, leave test equipment hooked up and go to CIRCUIT TEST QC.

2) Check CANP Solenoid Electrical Function Turn ignition on. Disconnect CANP solenoid. Connect DVOM positive test lead to VPWR terminal and negative test lead to CANP terminal at solenoid wiring harness connector. While observing DVOM, depress and release throttle several times to cycle output on and off. If CANP circuit voltage does not cycle 0.5 volt or more, remove jumper wire and go to step 6). If CANP circuit voltage cycles, remain in OUTPUT STATE CHECK and go to step 3).

3) Check Solenoid For Vacuum Leaks Turn ignition on. Leave CANP solenoid disconnected. Disconnect vacuum hose at CANP solenoid from manifold vacuum side of solenoid. Apply 16 in. Hg vacuum to manifold vacuum side of CANP solenoid. If CANP solenoid does not hold vacuum for 20 seconds, replace solenoid and repeat QUICK TEST . If fault is still present, service fuel evaporation canister or hoses. If CANP holds vacuum for 20 seconds, remain in OUTPUT STATE CHECK, leave vacuum pump attached and go to step 4).

4) Check Solenoid Mechanical Operation Connect CANP solenoid connector. Apply 16 in. Hg vacuum to manifold vacuum side of CANP solenoid. Depress and release throttle. If vacuum is released, check hose from CANP solenoid to canister for leaks and cracks. If hose is okay, remove jumper wire from STI to SIG RTN and go to step 5). If vacuum is not released, check hose from CANP solenoid to canister for leaks and cracks. If hose is okay, replace CANP solenoid and repeat QUICK TEST .

5) Check Vacuum Supply To CANP Solenoid Disconnect vacuum hose from CANP solenoid on manifold vacuum (PCV) side. Start engine. If vacuum is present at vacuum hose, EEC system is okay. Check evaporative canister. If vacuum is not present at hose, check vacuum hose for improper routing, kinks and blockage. If hose is okay, check engine for cause of low vacuum.

6) Code 85/565 Or 569: Check CANP Solenoid Resistance Code85/565 or 569 indicates fault in CANP solenoid circuit. For vehicles with dual CANP systems, Code 565 refers to CANP 1 while Code 569 refers to CANP 2. Possible causes for this fault are:

Faulty CANP solenoid.
Open in wiring harness circuit.
Shorted wiring harness circuit.
Faulty ECA.

Turn ignition off. Set DVOM on 200-ohm scale. Disconnect CANP solenoid connector. Measure CANP solenoid resistance. If resistance is 40-90 ohms, go to step 7). If reading is not 40-90 ohms, replace CANP solenoid and repeat QUICK TEST .

7) Check Voltage Of VPWR Circuit With CANP solenoid disconnected, turn ignition on. Measure voltage between VPWR terminal at CANP solenoid harness connector and negative battery terminal. If reading is 10.5 volts or more, go to step 8). If reading is less than 10.5 volts, repair open circuit and repeat QUICK TEST .

8) Check Continuity Of CANP Circuit Turn ignition off. Disconnect CANP solenoid. Disconnect 60-pin ECA connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving ECA disconnected. Measure resistance between CANP circuit breakout box test pin (No. 11 or 31) and CANP harness connector. If reading is less than 5 ohms, go to step 9). If reading is 5 ohms or more, repair open circuit. Reconnect components, and repeat QUICK TEST .

9) Check CANP Circuit For Short To Ground Turn ignition off. With CANP solenoid disconnected, measure resistance between CANP circuit breakout box test pin (No. 11 or 31) and pins No. 40, 46 and 60. If all readings are 10,000 ohms or more, go to step 10). If any reading is less than 10,000 ohms, repair short to ground. Reconnect components, and repeat QUICK TEST .

10) Check CANP Circuit For Short To Power Turn ignition off. With CANP solenoid disconnected, measure resistance between CANP circuit breakout box test pin (No. 11 or 31) and test pins No. 37 and 57. If all reading are 10,000 ohms or more, replace ECA and repeat QUICK TEST . If any reading is less than 10,000 ohms, repair short to power. Reconnect components, and repeat QUICK TEST . If code is repeated, replace ECA and repeat QUICK TEST.