Engine Controls - System/component Tests 3.0L: Other Mercury Villager I

Ground Circuits

1. Using a DVOM, check for continuity to ground on PCM terminals No. 6, 13, 39, 48, 107 and 108. (Scheme 23) Resistance should be zero ohms. If resistance is not zero ohms, repair open to ground.
2. Touch negative lead of voltmeter to a good ground. With vehicle running, backprobe positive lead of voltmeter to each ground terminal. Voltmeter should indicate less than one volt. If reading is greater than one volt, check for open, corrosion or loose connection on ground lead.

Power Circuits

Using a voltmeter, check for battery voltage between PCM terminal No. 46 (KAPWR) and ground. Check for battery voltage at terminals No. 38, 47 and 109 (VPWR). If battery voltage is not present, power is not being supplied from EEC power relay. See CIRCUIT TEST VPWR in TESTS W/CODES article.

PCM LOCATION

Scheme 23

ENGINE SENSORS & SWITCHES (PCM INPUTS)

Note. For additional sensor testing specifications, see SENSOR RANGE CHARTS article in the ENGINE PERFORMANCE section.

Camshaft Position (CMP) Sensor

Faults in CMP sensor or circuit should set a service code. See QUICK TEST in TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST CMP in TESTS W/CODES article for testing procedure.

Engine Coolant Temperature (ECT) Sensor

Sensor is located in intake manifold coolant passage at front of most engines. ECT sensor requires a 5-volt reference signal during engine operation. With sensor disconnected, sensor may be checked by measuring resistance between sensor terminals. For specifications, see SENSOR RANGE CHARTS article. For additional testing information, see CIRCUIT TEST ECT in TESTS W/CODES article.

EGR Control Solenoid

Faults in EGR control solenoid or circuit should set a service code. See QUICK TEST in TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST EGRC in TESTS W/CODES article for testing procedure.

EGR Temperature Sensor

Faults in EGR temperature sensor or circuit should set a service code. See QUICK TEST in TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST EGRT in TESTS W/CODES article for testing procedure.

Heated Oxygen Sensor (HO2S)

Sensor is located in exhaust pipe, upstream of catalytic converter. Faults in sensor or circuit should set a service code. See QUICK TEST in TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST HO2S in TESTS W/CODES article for additional sensor specifications and circuit testing procedures. Ensure that none of the following conditions exist

1. Moisture inside sensor/harness connector.
2. HO2S sensor coated with contaminants.
3. Sensor circuit open or shorted to ground.

Inertia Fuel Shutoff (IFS) Switch

Ensure ignition is off. Inertia switch is located behind bottom of left cowl panel. (Scheme 24)in THEORY/OPERATION article.

Note. In closed position, reset button can be depressed an additional 1/16" against spring. This is normal and does not affect IFS switch operation.

Push down on reset button to ensure switch is closed. Measure resistance between terminals on switch. If resistance is 5 ohms or less, switch is okay. If resistance is greater than 5 ohms, replace switch.

Knock Sensor (KS)

KS is located on cylinder block. Before continuing diagnosis, check fitness of engine, quality of fuel and basic spark timing. Faults in sensor or circuit should set a service code. See QUICK TEST in TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST KS in TESTS W/CODES article for additional sensor specifications and circuit testing procedures. Sensor is tested by substitution or by manually generating a knock to ensure sensor will set a service code.

Mass Airflow (MAF) Sensor

Faults in MAF sensor or circuit should set a service code. See QUICK TEST in TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST MAF in TESTS W/CODES article for sensor and circuit testing.

Park/Neutral Position (PNP) Switch

1. Turn ignition off. Connect scan tester to Diagnostic Link Connector (DLC). Using scan tester, read PNP switch signal when moving selector through gear range. If signal is on when selector is in Park and Neutral position, switch is okay. Fault is in Powertrain Control Module (PCM) or Transaxle Control Module (TCM). If signal is not on when selector is in Park and Neutral position, go to next step.
2. Leave ignition off. Disconnect PCM and TCM wiring harness connector. Install Breakout Box (007-00033) and Adaptor (007-00053), leaving PCM disconnected. Measure resistance between breakout box test pin No. 30 and the Green/Black wire terminal of TCM wiring harness connector. Resistance should be less than 5 ohms. Measure resistance between ground and breakout box test pin No. 30. Resistance should be greater than 10,000 ohms. If resistance is not as specified, repair open or short circuit in Green/Black wire. If resistance is as specified, fault is in PCM or TCM.

Power Steering Pressure (PSP) Switch

1. Turn ignition off. Connect scan tester to Diagnostic Link Connector (DLC). If scan tester is not available, go to next step. Start engine and warm to operating temperature. Using scan tester, read PSP switch signal while moving steering wheel in both directions. If signal is off before steering wheel is turned and on when steering wheel is turned 1/4 turn or more, system is normal and testing is complete. If signal is not as specified, go to next step.
2. Disconnect PSP connector. Start engine and allow to idle. Using ohmmeter, check for continuity between connector terminals. If continuity is present before steering wheel is turned and not present when steering wheel is turned, go to next step. If continuity is not as specified, replace PSP switch.
3. Turn ignition off. Measure resistance between PSP connector Black wire terminal and ground. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or short circuit in Black wire.
4. Leave ignition off and PSP disconnected. Disconnect PCM wiring harness connector. Install Breakout Box (007-00033) and Adaptor (007-00053), leaving PCM disconnected. Measure resistance between breakout box test pin No. 18 and the Pink wire terminal of PSP wiring harness connector. Resistance should be less than 5 ohms. Measure resistance between ground and breakout box test pin No. 18. Resistance should be greater than 10,000 ohms. If resistance is not as specified, repair open or short circuit in Pink wire. If resistance is as specified, replace PCM.

Throttle Position (TP) Sensor

Faults in TP sensor or circuit should set a service code. See QUICK TEST in TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST TP in TESTS W/CODES article for additional testing procedure. Ensure none of following conditions exist

1. Binding throttle linkage.
2. TP sensor loose or not seated properly.
3. Throttle plate not fully closed.

Vehicle Speed Sensor (VSS)

Faults in VSS sensor or circuit should set a service code. See QUICK TEST in TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST VSS in TESTS W/CODES article for additional testing procedure.

Fuel Pump Relay

Check 15-amp FUEL PUMP fuse. If fuse is okay, remove fuel pump relay located in left engine compartment relay block. Connect battery voltage to terminal "A". (Scheme 24) Ground terminal "B". Measure resistance between terminals "C" and "D". Resistance should be less than 5 ohms with power applied and greater than 10,000 ohms with power removed.

Scheme 24

Canister Purge (CANP) Solenoid

See FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS.

Idle Air Control (IAC) Solenoid

1. Solenoid is by-pass air type. Turn ignition off. Disconnect IAC solenoid harness connector. Turn ignition on. Measure voltage between ground and Blue/Yellow wire terminal of connector. If voltage is less than 10 volts, repair Blue/Yellow wire. If voltage is 10 volts or more, go to next step.
2. Turn ignition off. Measure resistance between IAC solenoid connector terminals. Resistance should be about 10 ohms. If resistance is as specified, go to next step. If resistance is not as specified, replace IAC solenoid.
3. Leave ignition off and IAC solenoid disconnected. Disconnect PCM wiring harness connector. Install Breakout Box (007-00033) and Adaptor (007-00053), leaving PCM disconnected. Measure resistance between breakout box test pin No. 21 and the Light Blue wire terminal of IAC solenoid wiring harness connector. Resistance should be less than 5 ohms. Measure resistance between ground and breakout box test pin No. 21. Resistance should be greater than 10,000 ohms. If resistance is not as specified, repair open or short circuit in Light Blue wire. If resistance is as specified, replace PCM.

FUEL SYSTEM

Note. In testing procedures, references to KOEO refer to Key On Engine Off. References to KOER refer to Key On Engine Running.

Note. For 1995 fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. For 1996 fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article.

FUEL SYSTEM PRESSURE RELEASE

Remove 15-amp FUEL PUMP fuse or disconnect Inertia Fuel Shutoff (IFS) switch. Start engine and operate it until it stalls. Turn ignition off. Reconnect fuse or IFS switch.

FUEL DELIVERY

Note. For fuel system pressure testing, see BASIC TESTING - 3.0L article. For 1995 fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. For 1996 fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article.

See RELAYS under RELAYS & SOLENOIDS.

Fuel Pressure Regulator

1. Release fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-23366-S05643198762001010300000) . Install fuel pressure gauge between fuel filter and fuel rail. Connect fuel pressure gauge in fuel line between fuel filter and fuel rail. Ensure main valve is open and drain valve is closed. Monitor fuel pressure gauge while performing the following: Start engine and operate for 10 seconds. Stop engine and wait for 10 seconds. Start engine and operate for 10 seconds.
2. Stop engine and remove pressure regulator vacuum hose. Check vacuum port for fuel. If fuel is present, replace fuel pressure regulator and repeat test. If fuel is not present, go to next step.
3. Connect vacuum pump to fuel pressure regulator vacuum port. Start engine. Apply vacuum to port. If fuel pressure drops when vacuum is applied, fuel pressure regulator is okay and testing is complete. If fuel pressure does not drop when vacuum is applied, replace fuel pressure regulator.

Fuel Injectors

Connect tachometer to engine. Start engine and allow to idle. Disconnect and reconnect injectors individually. If each injector causes a momentary drop in engine speed of at least 100 RPM, injectors are giving proper fuel delivery. RPM drop should only be momentary, as IAC will attempt to re-establish correct idle RPM. Replace any injectors that do not cause sufficient drop in engine speed.

Injector Circuit

1. Turn ignition off. Disconnect suspect fuel injector wiring harness connectors. Turn ignition on. Measure voltage between connector terminals. If voltage is 11-14 volts, go to next step. If voltage is not 11-14 volts, check fuse. If fuse is okay, repair Yellow wire in fuel injector circuit.
2. Leave fuel injector connector disconnected. Using an ohmmeter, measure resistance between fuel injector terminals. If resistance is not 10-14 ohms, replace fuel injector. If resistance is 10-14 ohms, fuel injector is okay and testing is complete.

IDLE CONTROL SYSTEM

See IDLE AIR CONTROL (IAC) SOLENOID under SOLENOIDS under RELAYS & SOLENOIDS.

IGNITION SYSTEMS

Note. For additional information and descriptions, see IGNITION SYSTEMS in THEORY/OPERATION article. Perform spark output check in BASIC TESTING - 3.0L article before these tests. Some ignition systems require that QUICK TEST be performed before testing. This will retrieve trouble codes from PCM memory. See TESTS W/CODES article.

IGNITION SYSTEM ACRONYMS (1)

Preliminary Check

Perform following preliminary checks

1. Visually inspect engine compartment to verify vacuum hoses and spark plug wires are properly routed and securely connected.
2. Examine all wiring harnesses and connectors for damage.
3. Ensure ICM is securely fastened to distributor base or cowl.
4. Ensure battery is fully charged.
5. All accessories should be off during diagnosis.

No Spark From Coil Secondary

1. Disconnect ignition coil wiring harness connector. Turn ignition on. Measure voltage between connector Blue/Yellow wire terminal and ground. If voltage is 10 volts or more, go to next step. If voltage is less than 10 volts, repair Blue/Yellow wire circuit.
2. Turn ignition off. Measure resistance between ignition coil primary terminals. Resistance should be 1.4-1.6 ohms. Measure resistance between ignition coil positive primary terminal and secondary terminal. (Scheme 25) Resistance should be 9800-10,000 ohms. If resistance is not as specified, replace ignition coil. If resistance is as specified, go to CIRCUIT TEST IGNS in the «TESTS W/CODES»(ref-23293) article.

Scheme 25

Faults in EGR control solenoid or circuit should set a service code. See QUICK TEST in TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST EGRC in TESTS W/CODES article for testing procedure.

Faults in EGR temperature sensor or circuit should set a service code. See QUICK TEST in TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST EGRT in TESTS W/CODES article for testing procedure.

EGR Valve

1. Ensure all vacuum hoses are correctly routed and securely attached. Replace any crimped or broken hoses. Ensure there is less than one in. Hg vacuum to EGR valve at idle with engine at normal operating temperature.
2. Install tachometer. Remove and plug vacuum hose at EGR valve. Start engine. Idle in Neutral. Note idle speed. Using hand vacuum pump, slowly apply 5-10 in. Hg vacuum to EGR valve. When vacuum is fully applied, engine should do one or more of following: Engine should stall. Idle speed should drop more than 100 RPM. Idle speed should return to normal when vacuum is released.

Repair or replace EGR valve if none of above occurs.

EGR Backpressure Transducer Valve

Locate EGR backpressure transducer valve between EGR valve and EGRC solenoid. Remove vacuum hoses from valve. Apply very light air pressure to bottom port of valve. If air flows freely, replace valve. If air does not flow freely, valve is okay.

EVAP Canister

There are no moving parts in canister. Check for loose, missing, cracked or broken connections and parts. Repair or replace as necessary. There should be no liquid in canister.

PCV Valve

1. Remove PCV valve from rocker cover grommet. Shake valve. If valve does not rattle when shaken, replace valve. Start engine and warm to normal operating temperature.
2. Disconnect hose from remote air cleaner or outlet tube. Place stiff piece of paper over hose end, and wait 60 seconds. Vacuum should hold paper in place. If vacuum does not hold paper in place, replace valve.

Wiring Diagram (Villager - 3.0L - 1 Of 2). Scheme 26

Wiring Diagram (Villager - 3.0L - 2 Of 2). Scheme 27