Engine Controls - System/component Tests - 2.0L: Other Mercury Mystique I

Ground Circuits

1. Using a DVOM, check for continuity to ground at PCM connector terminals No. 24, 51, 77 and 103. (Scheme 188) Resistance should be approximately zero ohms. If resistance is not approximately zero ohms, repair circuit 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

Turn ignition off. Using a voltmeter, check for battery voltage between ground and PCM terminal No. 55 (KAPWR). Turn ignition to START or RUN position. Check for battery voltage between ground and PCM connector terminals No. 71 and 97. If battery voltage is not present, power is not being supplied from EEC power relay. See CIRCUIT TEST B in TESTS W/CODES - 2.0L article.

PCM LOCATIONS

Identifying PCM 104-Pin Connector Terminals. Scheme 188

ENGINE SENSORS & SWITCHES

Note. For additional sensor testing specifications, see SENSOR RANGE CHARTS - 2.0L article.

Clutch Pedal Position (CPP) Switch

1. Turn ignition off. Locate CPP switch near clutch pedal. Inspect switch and bracket for damage and repair if necessary. Disconnect CPP switch wiring harness connector. Inspect terminals for damage and repair if necessary.
2. Measure resistance between switch terminals. If resistance is 5 ohms or more, replace CPP switch If resistance is less than 5 ohms, see CIRCUIT TEST TA in «TESTS W/CODES - 2.0L»(ref-24082) article for additional testing and specifications.

Engine Coolant Temperature (ECT) Sensor

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 ECT SENSOR SPECIFICATIONS table. For additional testing information, see CIRCUIT TEST DA in TESTS W/CODES - 2.0L article.

ECT SENSOR SPECIFICATIONS (1)

Heated Oxygen Sensor (HO2S)

Ensure that none of following conditions exist

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

Faults in sensor or circuit should set a Diagnostic Trouble Code (DTC). See QUICK TEST in TESTS W/CODES - 2.0L article. If no diagnostic trouble code has been set, go to step 34) of CIRCUIT TEST H in TESTS W/CODES - 2.0L article to check HO2S heater resistance.

Inertia Fuel Shutoff (IFS) Switch

1. Ensure ignition is off. Locate IFS switch. See «INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION»(ref-24113-S04646377142001010400000) table. Push down on reset button to ensure switch is closed. Measure resistance between switch terminals.
2. If resistance is more than 5 ohms, replace switch. If resistance is 5 ohms or less, switch is okay. If vehicle does not start, go to CIRCUIT TEST A in «TESTS W/CODES - 2.0L»(ref-24082) 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.

INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION

Intake Air Temperature (IAT) Sensor

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 IAT SENSOR SPECIFICATIONS table. For additional testing information, see CIRCUIT TEST DA in TESTS W/CODES - 2.0L article.

IAT SENSOR SPECIFICATIONS (1)

Mass Airflow (MAF) Sensor

Faults in MAF sensor or circuit should set a Diagnostic Trouble Code (DTC). See QUICK TEST in TESTS W/CODES - 2.0L article. If no diagnostic trouble code has been set, go to CIRCUIT TEST DC in TESTS W/CODES - 2.0L article for MAF sensor and circuit testing.

Park/Neutral Position (PNP) Switch

1. Turn ignition off. Locate PNP switch near transmission shift linkage. Inspect switch and bracket for damage and repair if necessary. Disconnect PNP switch wiring harness connector.
2. Inspect terminals for damage and repair if necessary. Measure resistance between switch terminals. If resistance is 5 ohms or more, replace PNP switch If resistance is less than 5 ohms, see CIRCUIT TEST TA in «TESTS W/CODES - 2.0L»(ref-24082) article for additional testing procedures.

Throttle Position (TP) Sensor

Ensure none of following conditions exist

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

Faults in TP sensor or circuit should set a diagnostic trouble code. See QUICK TEST in TESTS W/CODES - 2.0L article. If no diagnostic trouble code has been set, see CIRCUIT TEST DH in TESTS W/CODES - 2.0L article for additional sensor testing and specifications.

Fuel Pump Relay

1. Turn ignition off. Leave fuel pump relay disconnected. Measure resistance between terminals No. 1 or No. 85 and all other terminals. To Identify fuel pump relay terminals, refer to numbers molded on relay.
2. Resistance should be either 40-120 ohms, or greater than 10,000 ohms. Replace fuel pump relay if resistance is not as specified. If resistance is okay, see CIRCUIT TEST KA in «TESTS W/CODES - 2.0L»(ref-24082) article for additional testing procedures.

Canister Vent (CV) Solenoid

See FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS.

Canister Purge (CANP) Solenoid

See FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS.

EGR Solenoid

See EXHAUST GAS RECIRCULATION (EGR) under EMISSION SYSTEMS & SUB-SYSTEMS.

Idle Air Control (IAC) Solenoid

1. Solenoid is by-pass air type. Ensure ignition is off. Disconnect IAC solenoid harness connector. Measure resistance between IAC solenoid connector terminals. Solenoid has diode. (Scheme 189) Connect DVOM (+) test lead to terminal VPWR (Red wire) and DVOM (-) lead to the other IAC solenoid terminal.
2. Resistance should be 6-13 ohms. If resistance is not 6-13 ohms, replace solenoid. If resistance is 6-13 ohms, IAC solenoid is okay. See CIRCUIT TEST KE in «TESTS W/CODES - 2.0L»(ref-24082) article for additional testing and specifications.

With Fuel Pressure Gauge

Remove fuel tank cap to release fuel tank pressure. Connect Fuel Pressure Gauge (T80L-9974-B), to pressure relief valve (Schrader valve), located on fuel injection manifold rail. Using a suitable container, release fuel pressure.

Without Fuel Pressure Gauge

If fuel pressure gauge is not available, disconnect Inertia Fuel Shutoff (IFS) switch. IFS switch is located behind right kick panel. Remove fuel cap to release fuel tank pressure. Crank engine for 15 seconds to release system pressure.

See RELAYS under RELAYS & SOLENOIDS.

1. System Integrity Check Perform the following checks: Visually inspect fuel system (fuel lines, filter, pump, injectors, pressure regulator, etc.). Ensure Inertia Fuel Shutoff (IFS) switch reset button is not in upper (tripped) position. Ensure battery is fully charged and fuel-related fuses are okay. Check fuel tank contents and fuel gauge accuracy. On vehicles with 2 fuel tanks, check both tanks. If any fault is detected, repair as necessary. If system checks are okay, go to next step.
2. Check Fuel Pressure Install fuel pressure gauge. Check and record fuel pressure. For fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(ref-123323) article. If fuel pressure is as specified, testing is complete. If fuel pressure is not as specified, go to step 52) of CIRCUIT TEST H in «TESTS W/CODES - 2.0L»(ref-24082) article.

FUEL PRESSURE REGULATOR

1. Ensure ignition is off. Connect fuel pressure gauge to Schrader valve on fuel rail. Ensure manifold vacuum supply tube is connected to fuel pressure regulator. Start engine and run for 10 seconds. Stop engine and wait 10 seconds. Start engine and operate for 10 seconds. Stop engine. Remove pressure regulator vacuum hose. Check vacuum port for fuel.
2. If fuel is present, replace fuel pressure regulator and repeat test. If fuel is not present, start engine and run for 30 seconds. Stop engine. Check fuel pressure gauge. If pressure does not drop, go to step 4). If pressure drops more than 5 psi (34 kPa) in 60 seconds, disconnect and plug fuel return line at engine. Cycle ignition on and off until normal fuel pressure is obtained.
3. Turn ignition off. Check fuel pressure gauge. If pressure drops more than 5 psi (34 kPa) in 30 seconds, replace fuel pump assembly. If pressure does not drop more than 5 psi (34 kPa) in 30 seconds, replace fuel pressure regulator.
4. Ensure ignition is off. Relieve fuel pressure. Remove fuel pressure regulator. Check "O" ring, gasket and mounting surfaces for cracks, cuts or other damage. Connect vacuum pump to fuel return tube, and apply 20 in. Hg vacuum. If maximum vacuum loss exceeds 10 in. Hg in 10 seconds, replace regulator. If maximum vacuum loss does not exceed 10 in. Hg in 10 seconds, recheck entire fuel delivery system for cause of fuel pressure loss.

Fuel Injector Resistance

Disconnect injector harness connectors. Using digital ohmmeter, measure resistance between injector terminals. See INDIVIDUAL INJECTOR RESISTANCE table. Replace any injector not within specification.

Fuel Injector Check

Start engine and allow to idle. If engine will not start, crank engine for 10 seconds. Using a stethoscope, listen for clicking sound at each injector. If clicking sound is heard, fuel injector is operating. If clicking sound is not heard, go to step 8) of CIRCUIT TEST HD in TESTS W/CODES - 2.0L article.

INDIVIDUAL INJECTOR RESISTANCE (1)

IDLE CONTROL SYSTEM

1. Check Idle Air Control (IAC) Solenoid Resistance Turn ignition off. Disconnect IAC wiring harness connector. Connect DVOM positive lead to VPWR (White/Red wire) terminal of IAC solenoid wiring harness connector. Connect DVOM negative lead to IAC terminal. If resistance is 6-13 ohms, go to next step. If resistance is not 6-13 ohms, replace IAC valve assembly.
2. Check IAC Solenoid Internal Short To Case Turn ignition off. Measure resistance between each wiring harness connector terminal and IAC housing. If either resistance is less than 10,000 ohms, replace IAC solenoid assembly. If each resistance is 10,000 ohms or more, IAC solenoid is okay. If fault is still present, go to CIRCUIT TEST KE in «TESTS W/CODES - 2.0L»(ref-24082) article for additional testing.

IGNITION SYSTEM

Note. For additional information and descriptions, see IGNITION SYSTEMS in THEORY/OPERATION - 2.0L article.

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 all ground connections are clean and tight.
4. Ensure battery is fully charged.
5. All accessories should be off during diagnosis.

SECONDARY AIR INJECTION

Faults in idle control system or circuit should set a Diagnostic Trouble Code (DTC). See QUICK TEST in TESTS W/CODES - 2.0L article. If DTC has not been set

1. On models equipped with Electronic Air Injection System (EAIR), go to step 1) of CIRCUIT TEST HM in «TESTS W/CODES - 2.0L»(ref-24082) article.
2. On models equipped with mechanical secondary air injection system (EAIR), go to step 40) of CIRCUIT TEST HM in «TESTS W/CODES - 2.0L»(ref-24082) article.

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. Disconnect Idle Air Control (IAC) wiring harness connector. 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 the following: Engine should stall. Idle speed should drop more than 100 RPM. Idle speed should return to normal when vacuum is released.
3. Service or replace EGR valve if engine does not stall or idle speed does not respond as specified. Reconnect IAC harness connector. Unplug and reconnect vacuum hose at EGR valve.

EGR Vacuum Regulator (EVR) Solenoid

1. Turn ignition off. Disconnect EVR solenoid wiring harness connector. Measure resistance between EVR terminals. If resistance is 26-40 ohms, EVR solenoid is okay. If resistance is not 26-40 ohms, replace EVR solenoid.
2. Leave ignition off. Disconnect PCM 104-pin connector. Inspect for damage pins and repair if necessary. Connect EEC-V Breakout Box (014-000950) to wiring harness. Connect PCM to breakout box. Connect EVR solenoid to wiring harness connector. Disconnect hose from EGR valve. Connect EGR vacuum hose to vacuum gauge.
3. Start engine and allow to idle. Connect test pin No. 47 (EVR) at breakout box to chassis ground. If vacuum gauge reading is 4 in. Hg or more, replace PCM. If vacuum gauge is less than 4 in. Hg, replace EVR solenoid.

Turn ignition off. Disconnect CANP solenoid wiring harness connector. Measure resistance between CANP solenoid terminals. If resistance is not as specified, replace CANP solenoid. If resistance is 30-90 ohms, solenoid is okay. If fault is still present, go to CIRCUIT TEST HW in TESTS W/CODES - 2.0L article.

Purge Flow (PF) Sensor

Turn ignition off. Disconnect PF sensor wiring harness connector. Allow sensor to cool to room temperature. Measure resistance between PFS SIG terminal and VPWR terminal. (Scheme 189) If resistance is not 40-230 ohms, replace PF sensor. If resistance is 40-230 ohms, sensor is okay. If fault is still present, go to CIRCUIT TEST HW in TESTS W/CODES - 2.0L article.

Identifying Purge Flow Sensor Connector Terminals. Scheme 189

Vapor Management Valve (VMV)

Turn ignition off. Disconnect VMV solenoid wiring harness connector. Measure resistance between VMV terminals. If resistance is not 30-36 ohms, replace VMV. If resistance is 30-36 ohms, VMV is okay. If fault is still present, go to CIRCUIT TEST HW in TESTS W/CODES - 2.0L article.

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.

POSITIVE CRANKCASE VENTILATION (PCV)

1. Check PCV Valve Remove PCV valve. Shake valve and listen for rattle. If PCV valve rattles when shaken, go to next step. Replace PCV valve if it does not rattle when shaken.
2. Check PCV System Start engine and warm to normal operating temperature. Disconnect hose from remote air cleaner or outlet tube. Place a stiff piece of paper over end of hose. If vacuum from hose does not hold paper in place for one minute, go to next step. If vacuum from hose holds paper in place for one minute, PCV system is okay and testing is complete.
3. Check Evaporative Emission System Disconnect evaporative emission hose from PCV system and plug connector. Place a stiff piece of paper over end of hose. If vacuum from hose does not hold paper in place for one minute, isolate vacuum leak or restriction and repair as necessary. If vacuum from hose holds paper in place for one minute, proceed as follows: On models equipped with Fuel Tank Pressure (FTP) sensor, see step 47) of CIRCUIT TEST HX in «TESTS W/CODES - 2.0L»(ref-24082) article. On models not equipped with Fuel Tank Pressure (FTP) sensor, go to step 10) of CIRCUIT TEST HW in «TESTS W/CODES - 2.0L»(ref-24082) article.