Engine Controls - System/component Tests: Other Ford Bronco V

Due to Federal government requirements, manufacturers may use names and acronyms for systems and components different than those used in previous years. Following table will help eliminate confusion when dealing with these components and systems. Only relevant components and systems whose names have changed from current Ford Motor Co. terminology have been listed. See REVISED TERMINOLOGY table.

REVISED TERMINOLOGY

Ground Circuits

1. Using a DVOM, check for continuity to ground on PCM terminals No. 20, 40 and 60. (Scheme 80) 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. 1 (KAPWR) and ground. Check for battery voltage at terminals No. 37 and 57 (VPWR). If battery voltage is not present, power is not being supplied from EEC power relay. See CIRCUIT TEST B in appropriate TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section.

PCM LOCATION

Scheme 80

ENGINE SENSORS & SWITCHES (PCM INPUTS)

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

BAROMETRIC PRESSURE (BARO) SENSOR

Faults in barometric pressure sensor or circuit should set a service code. See QUICK TEST in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section. If no service code has been set, see CIRCUIT TEST DF in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section for sensor specifications.

CLUTCH PEDAL POSITION (CPP) SWITCH

See PARK/NEUTRAL POSITION (PNP) SWITCH.

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

Sensor is located in intake manifold coolant passage at front of most engines. On all models, 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 in the ENGINE PERFORMANCE section. For additional testing information and circuit testing of sensor, see CIRCUIT TEST DA in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section.

EGR VALVE POSITION (EVP) SENSOR/EVR SOLENOID

Faults in sensor or circuit should set a service code. See QUICK TEST in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section. If no service code has been set, see CIRCUIT TEST DN in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section for sensor specifications and circuit testing procedure.

HEATED OXYGEN SENSOR (HO2S)

Vehicle may be equipped with one or 2 HO2S sensors. They are located in exhaust pipe, upstream of catalytic converters. Faults in sensor or circuit should set a service code. See QUICK TEST in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section. If no service code has been set, see CIRCUIT TEST H in appropriate TESTS W/CODES - EEC-IV article for additional sensor specifications and circuit testing procedures. Ensure that none of 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 may be found in the following location

1. On floorboard to left and above steering column.

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. For additional circuit testing information, refer to CIRCUIT TEST J in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section. If resistance is greater than 5 ohms, replace switch.

INTAKE AIR TEMPERATURE (IAT) SENSOR

1. Sensor is located in intake runner. Sensor requires a 5-volt reference signal during engine operation. With sensor disconnected, sensor may be checked by measuring resistance between sensor terminals. NOTE: Engine Coolant Temperature (ECT) sensor and IAT sensor terminal connectors are identical. Ensure testing is done on proper component.
2. For specifications, see «SENSOR RANGE CHARTS»(ref-23017) article in the ENGINE PERFORMANCE section. For additional testing information and circuit testing of sensor, see CIRCUIT TEST DA in appropriate «TESTS W/CODES - EEC-IV»(ref-22952) article in the ENGINE PERFORMANCE section.

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 - EEC-IV article in the ENGINE PERFORMANCE section. If no service code has been set, see CIRCUIT TEST DG in TESTS W/CODES - EEC-IV 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.

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR

Sensor is located on engine or firewall and is connected to intake manifold by a vacuum supply hose. Remove vacuum supply hose to sensor. Install vacuum pump to sensor and apply 18 in. Hg vacuum. Sensor should hold vacuum. If sensor does not hold vacuum, replace sensor. Faults in MAP sensor or circuit should set a service code. See QUICK TEST in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section. If no service code has been set, see CIRCUIT TEST DF in TESTS W/CODES - EEC-IV article for additional sensor testing and specifications.

MASS AIRFLOW (MAF) SENSOR

Faults in MAF sensor or circuit should set a service code. See QUICK TEST in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section. If no service code has been set, see CIRCUIT TEST DC in appropriate article for sensor specifications and circuit testing.

PARK/NEUTRAL POSITION (PNP) SWITCH

With ignition switch in OFF position, set DVOM to 200-ohm scale. Locate PNP switch (on transmission) and CPP switch (on clutch pedal linkage). Disconnect harness at switch. Measure resistance across PNP terminals with transmission in Neutral and across CPP terminals with clutch pedal fully depressed. If any resistance is greater than 5 ohms, switch is open. Replace switch as necessary. Faults in switches or switch circuits should set a service code. See QUICK TEST in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section. If no service code has been set, see CIRCUIT TEST TA in TESTS W/CODES - EEC-IV article for additional switch testing and specifications.

POWER STEERING PRESSURE (PSP) SWITCH

1. Disconnect PSP connector at steering gearbox or line. Set DVOM to 200-ohm scale and connect test leads to switch. With steering wheel centered, resistance should be less than 10 ohms. Start engine. Turn steering wheel 1/2 turn, then return it to centered position.
2. Resistance should change from less than 10 ohms to infinity when steering wheel is turned and return to less than 10 ohms when steering wheel is returned to centered position. Faulty PSP or circuit should set a service code. See QUICK TEST in appropriate «TESTS W/CODES - EEC-IV»(ref-22952) article in the ENGINE PERFORMANCE section. If no service code has been set, see CIRCUIT TEST FF in appropriate «TESTS W/CODES - EEC-IV»(ref-22952) article for additional switch testing and specifications.

THROTTLE POSITION (TP) SENSOR

Faults in TP sensor or circuit should set a service code. See QUICK TEST in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section. If no service code has been set, see CIRCUIT TEST DH in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section for additional sensor testing and specifications. 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)

Disconnect VSS electrical connector. Using DVOM, measure resistance across sensor terminals. Resistance should be 190-250 ohms. Replace sensor if not within specification. Faults in VSS sensor or circuit should set a service code. See QUICK TEST in appropriate TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section. If no service code has been set, see CIRCUIT TEST DP in appropriate TESTS W/CODES - EEC-IV article for additional sensor testing and specifications.

RELAYS

Note. For more fuel delivery system testing, see CIRCUIT TEST J in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section.

Fuel Pump Relay

Remove relay from vehicle. Connect battery voltage to terminal "C". (Scheme 81) Ground terminal "D". Measure resistance between terminals "A" and "B". Resistance should be less than one ohm with power applied and greater than 10 k/ohms with power removed.

Scheme 81

Air Management Solenoid

Disconnect solenoid harness connector, and measure resistance across terminals. Resistance should be 50-100 ohms. If resistance is not as specified, replace solenoid. Faults in solenoid or circuit should set a service code. See QUICK TEST in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section. If no service code has been set, see CIRCUIT TEST KC in TESTS W/CODES - EEC-IV article for additional solenoid and circuit testing.

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. Set DVOM to 200-ohm scale. Measure resistance between IAC solenoid connector terminals. (Scheme 82) Solenoid has diode. Connect DVOM (+) test lead to terminal VPWR and DVOM (-) lead to terminal IAC.
2. Resistance should be 6-13 ohms. If resistance is not as specified, replace solenoid. Faults in IAC solenoid or circuit should set a service code. See QUICK TEST in «TESTS W/CODES - EEC-IV»(ref-22952) article in the ENGINE PERFORMANCE section. If no service code has been set, see CIRCUIT TEST KE in «TESTS W/CODES - EEC-IV»(ref-22952) article for additional testing and specifications.

Scheme 82

FUEL SYSTEM

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

FUEL SYSTEM PRESSURE RELEASE

1. Remove fuel tank cap. Using Fuel Pressure Gauge (T80L-9974-B), release pressure from system at pressure relief valve (Schrader valve), located on fuel injection manifold rail.
2. If fuel pressure gauge is not available, disconnect electrical connector to inertia switch located on left side of luggage compartment. Remove fuel cap to release fuel tank pressure. Crank engine for 15 seconds to release system pressure.

FUEL DELIVERY

Note. For fuel system pressure testing, see BASIC TESTING article. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article.

See RELAYS under RELAYS & SOLENOIDS.

Scheme 83

Scheme 84

1. Visually inspect entire fuel delivery system for leaks and damaged or kinked lines and hoses. Ensure battery is fully charged and fuses are okay. Ensure adequate fuel is available in fuel tank. Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE. Install fuel pressure gauge. With Key On Engine Off (KOEO) to activate pump, check and record fuel pressure. For fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(ref-123320) article. Proceed to appropriate step, as indicated: If fuel pressure is within specification, go to step 2). If fuel pressure is zero, go to step 5). If fuel pressure is low, go to step 11). If fuel pressure is high, go to step 12).
2. Check fuel injectors. See FUEL CONTROL. Crank or run engine. Using a mechanic's stethoscope, listen for regular clicks at each injector. If sound is present, check fuel injectors for flow and leakage. Clean or replace injectors as necessary.
3. If injector clicking is not present, check fuel injector resistance. See FUEL CONTROL. If injector is not within specification, replace as necessary. If injector is within specification, check injector electrical connections for continuity to PCM. If no continuity exists in circuit, check for 12 volts at each injector lead.
4. If voltage is not present at injector, see QUICK TEST in «TESTS W/CODES - EEC-IV»(ref-22952) article in the ENGINE PERFORMANCE section. Faults in injector circuit should set a service code. If no service code has been set, see CIRCUIT TEST H in «TESTS W/CODES - EEC-IV»(ref-22952) article in the ENGINE PERFORMANCE section.
5. If fuel pressure is zero, ensure battery is fully charged and ignition is off. Ground fuel pump lead. Using a jumper lead, ground terminal FP at Data Link Connector (DLC). (Scheme 83) Ensure connection is okay at pump/sender unit. Turn ignition on, engine off. Listen for sound of fuel pump running. If pump is running, proceed to next step. If fuel pump is not running, proceed to step 7).
6. Check condition of high-pressure fuel filter. If filter is free of contamination, check fuel pressure regulator. If filter is contaminated, replace filter and recheck system pressure as outlined in step 1).
7. Turn ignition off, and disconnect fuel pump/sender or high pressure pump connector. Set DVOM on 200-ohm scale. Measure resistance between pump ground at pump connector and chassis ground. (Scheme 84) If resistance is one ohm or more, repair open circuit to ground. If resistance is less than one ohm, go to next step.
8. Ensure ignition is off and battery is fully charged. Disconnect harness connector from pump/sender unit. Ground terminal FP at data link connector. With KOEO and DVOM on 20-volt scale, measure voltage at terminal PUMP POWER of pump/sender or high pressure pump connector. If voltage is 10.5 volts or more, replace pump/sender assembly. If voltage is not as specified, go to next step.
9. With KOEO, backprobe fuel pump inertia switch connector. If voltage is 10.5 volts or more at both inertia switch terminals, repair wire between inertia switch and pump. If voltage is not as specified, reset or replace inertia switch as necessary and go to next step.
10. Ensure ignition is off and battery is fully charged. Ground terminal FP at data link connector. With KOEO and DVOM on 20-volt scale, measure voltage at fuel pump relay (Dark Green/Yellow wire). If voltage is 10.5 volts or more at relay, repair Dark Green/Yellow wire between fuel pump relay and inertia switch. If voltage is not as specified, check voltage supply to fuel pump relay and to terminal No. 1 at PCM. For additional circuit testing information, see CIRCUIT TEST J in «TESTS W/CODES - EEC-IV»(ref-22952) article in the ENGINE PERFORMANCE section.
11. Ground terminal FP at data link connector. Using a DVOM, check voltage at fuel pump terminal (Pink/Black wire). If voltage at fuel pump is within.5 volt of battery voltage, go to step 6). If voltage is not as specified, go to step 5).
12. Check engine compartment vacuum hose for leaks. Ensure engine produces normal vacuum. See FUEL PRESSURE REGULATOR.

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. 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 high pressure fuel pump (dual pump system) or fuel sender/pump assembly (single pump type). 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. (Scheme 85) 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 Selector Valve

Information is not available.

Scheme 85

Fuel Injectors

1. Connect tachometer to engine. Run engine at 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.
2. Replace any injectors that do not cause sufficient drop in engine speed. When test is complete and all injectors cause equal drop in speed, shut off engine. In order to check curb idle, refer to emission control specifications on decal in engine compartment.

Injector Circuit

1. Disconnect all injector harness connectors. Using a DVOM, check resistance across terminals of each injector. See INDIVIDUAL INJECTOR RESISTANCE table.
2. Disconnect injector bank harness connector, and check resistance of injector bank. See INJECTOR BANK RESISTANCE table. Repair wiring or replace any injector circuit not within specification.

INDIVIDUAL INJECTOR RESISTANCE

INJECTOR BANK RESISTANCE

IDLE CONTROL SYSTEM

See IDLE AIR CONTROL (IAC) SOLENOID under SOLENOIDS under RELAYS & SOLENOIDS. Curb idle and fast idle speed are controlled by Powertrain Control Module (PCM) and are not adjustable. Some throttle bodies have a sludge-tolerant design with a special coated throttle bore. A Yellow/Black warning decal on these units warns against backing off throttle plate adjustment screw to avoid throttle plate sticking in bore. Faults in idle control system components or circuit should set a service code. See QUICK TEST in appropriate TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section.

IGNITION SYSTEMS

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

IGNITION SYSTEM ACRONYMS (1)

IGNITION SYSTEM IDENTIFICATION

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 START W/ SPOUT CONNECTOR DISCONNECTED (REMOTE MOUNTED ICM)

1. Ensure SPARK OUTPUT CHECK has been performed. See NO-START DIAGNOSIS in «BASIC TESTING»(ref-23003) article in the ENGINE PERFORMANCE section. Turn ignition on. Ensure battery has 12 volts. WARNING: DO NOT connect EEC-IV diagnostic cable and PCM to EEC-IV breakout box simultaneously.
2. Turn ignition off. Connect DI Diagnostic Cable (007-00097) to EEC-IV Breakout Box (T83L-50-EECIV), negative battery terminal and ICM. see scheme 8 Leave B+ lead disconnected. Ensure PIP OPEN/NORMAL/SPOUT OPEN switch is in NORMAL position. Apply DI overlay on breakout box.
3. Disconnect SPOUT connector. Set DVOM on A/C scale. Crank engine while measuring voltage between J7 (B -) and J15 (PIP). If voltage is 3.0-8.5 volts AC, replace ICM. If voltage is not 3.0-8.5 volts AC, connect diagnostic cable to CMP sensor and sensor connector.
4. Turn switch to PIP OPEN position. Crank engine while measuring voltage between J7 (B -) and J34 (PIP). If voltage is 3.0-8.5 volts AC, repair open in PIP circuit between ICM and CMP sensor. If voltage is not 3.0-8.5 volts AC, check CMP wiring harness connector. If connector is okay, replace CMP sensor.

CONTINUOUS MEMORY CODE 18 OR 212 (IDM MISSING)

1. Ensure SPARK OUTPUT CHECK has been performed. See NO-START DIAGNOSIS in «BASIC TESTING»(ref-23003) article in the ENGINE PERFORMANCE section. Turn ignition on.
2. Turn ignition off. Connect DI Diagnostic Cable (007-00097) to EEC-IV Breakout Box (T83L-50-EECIV), negative battery terminal and ICM. see scheme 8 Leave B+ lead disconnected. Ensure PIP OPEN/NORMAL/SPOUT OPEN switch is in NORMAL position.
3. Apply DI overlay on breakout box. Disconnect PCM. For CCD (Black module) equipped systems, go to step 6). For non-CCD (Gray module) equipped systems, set DVOM on DC scale. Disconnect ignition coil wiring harness connector. Turn ignition on.
4. Measure voltage between J7 (B -) at breakout box and terminal No. 4 (IDM) at PCM wiring harness connector. If voltage is greater than 5.0 volts DC, repair IDM circuit short to power between PCM and IDM 22-k/ohm resistor. If voltage is less than 5.0 volts DC, turn ignition off.
5. Measure resistance between J7 (B -) at breakout box and terminal No. 4 (IDM) at PCM wiring harness connector. If resistance is less than 10,000 ohms, repair IDM circuit short to ground between PCM and IDM 22-k/ohm resistor. If resistance is 10,000 ohms or more, measure resistance between J4 (COIL-) at breakout box and terminal No. 4 (IDM) at PCM wiring harness connector. If resistance is not 20-24 k/ohms, repair open or shorted IDM circuit.
6. Turn ignition off. Set DVOM on AC scale. Crank engine while measuring voltage between J7 (B -) at breakout box and terminal No. 4 (IDM) at PCM wiring harness connector. If voltage is greater than 1.0 volt AC, replace PCM. If voltage is not greater than 1.0 volt AC, turn ignition off.
7. Disconnect diagnostic connector from ICM. Leave ICM wiring harness connector connected to diagnostic cable. Set DVOM on DC scale. Turn ignition on. Measure voltage between J7 (B-) and J23 (IDM). If voltage is less than 0.5 volt, repair short to power in IDM circuit between PCM and ICM wiring harness connector.
8. If voltage is 0.5 volt or more, turn ignition off. Measure resistance between J7 (B-) and J23 (IDM). If resistance is less than 10,000 ohms, repair short to ground in IDM circuit between PCM and ICM wiring harness connector. If resistance is greater than 10,000 ohms, measure resistance between J23 (IDM) and terminal No. 4 of PCM wiring harness connector. If resistance is 5 ohms or less, replace ICM. If resistance is greater than 5 ohms, repair open in IDM circuit between PCM and ICM wiring harness connector.

KOER CODE 18 OR 213 (INCORRECT IGNITION TIMING)

1. Check ignition timing. See IGNITION TIMING in «ADJUSTMENTS»(ref-22969) article in the ENGINE PERFORMANCE section. If ignition timing is correct, testing is complete. If ignition timing is not correct, turn ignition off.
2. Connect DI Diagnostic Cable (007-00097) to EEC-IV Breakout Box (T83L-50-EECIV), negative battery terminal and ICM. see scheme 8 Leave B+ lead disconnected. Ensure PIP OPEN/NORMAL/SPOUT OPEN switch is in SPOUT OPEN position. Apply DI overlay on breakout box.
3. Set DVOM on DC scale. Start engine and allow to idle. Measure voltage between J7 (B-) and J10 (SPOUT). If voltage is 3.0-8.5 volts, replace ICM. If voltage is not 3.0-8.5 volts, turn ignition off. Disconnect PCM wiring harness connector.
4. Disconnect diagnostic connector from ICM. Leave ICM wiring harness connector connected to diagnostic cable. Measure resistance between J10 (SPOUT) at breakout box and terminal No. 36 (SPOUT) at PCM wiring harness connector. If resistance is less than 5 ohms, replace PCM. If resistance is 5 ohms or more, repair open in SPOUT circuit between PCM and ICM wiring harness connector.

SECONDARY AIR INJECTION

Air Supply Pump

Check belt tension, and adjust to proper tension if necessary. Disconnect air supply hose from by-pass control valve. Start engine. Pump is operating satisfactorily if airflow is felt at pump outlet and airflow increases as engine speed is increased. If pump does not operate as specified, replace pump.

Air Silencer/Filter (Air Pump & Pulse Air Inlet)

Inspect hoses and air silencer for leaks. Disconnect hose from air silencer outlet. Remove silencer from vehicle, and visually inspect for plugging. If no plugging or leaks are found, silencer is okay. If any plugging or leaks are found, repair or replace as required.

Scheme 86

1. Disconnect air supply hose at valve outlet. (Scheme 86) Remove vacuum line from vacuum nipple, and check for presence of vacuum at nipple. Ensure vacuum exists at nipple before proceeding.
2. Reconnect vacuum line to vacuum nipple. With engine at 1500 RPM, air pump supply air should be heard and felt at air by-pass valve outlet.
3. With engine still at 1500 RPM, disconnect vacuum line. Air at outlet should decrease significantly or shut off. Air pump supply air should now be heard or felt at silencer ports or at dump port.
4. If normally closed air by-pass valve does not perform as described in steps 2) and 3), check air pump for faults. If air pump is operating satisfactorily, replace air by-pass valve.

Air Injection By-Pass Valve (Normally Open)

1. Disconnect air supply hose at inlet. Accelerate engine to 1500 RPM and verify presence of airflow in hose. Reconnect air supply hose to valve inlet.
2. Carefully disconnect air supply hoses at outlets "A" and "B". (Scheme 87) Carefully remove vacuum line at vacuum nipple. Accelerate engine to 1500 RPM. Airflow should be heard and felt at outlet "B" with little or no airflow at outlet "A".
3. Connect a vacuum line from manifold vacuum fitting to air control valve vacuum nipple. Accelerate engine to 1500 RPM. Airflow should be heard and felt at outlet "A" with little or no airflow at outlet "B".
4. If conditions in steps 2) and 3) are not as specified, replace air control valve. If valve operates satisfactorily, restore all hose and vacuum connections.

Scheme 87

Air Check Valve

1. Visually inspect hoses, tubes, control valve(s) and check valve(s) for leaks that may be due to backflow of exhaust gases. If holes are found and/or traces of exhaust gas products are evident, check valve may be suspect.
2. Valve should allow free flow of air in direction of arrow only. (Scheme 88) Valve(s) should check (or block) free flow of exhaust gas air in opposite direction. If air does not flow as indicated or if exhaust gas backflows opposite of direction of arrow in illustration, replace check valve.

Scheme 88

Air Injection Diverter Valve (Without Vent)

1. With engine cold, vacuum signal should be present at valve. Disconnect air supply hose at inlet. Accelerate engine to 1500 RPM and verify presence of airflow in hose. Reconnect air supply hose to valve inlet.
2. Disconnect air supply hoses at outlets "A" and "B". (Scheme 89) Remove vacuum line at vacuum nipple. Accelerate engine to 1500 RPM. Airflow should be heard and felt at outlet "B" with little or no airflow at outlet "A".
3. Connect a vacuum line from manifold vacuum fitting to air supply control valve vacuum nipple. Accelerate engine to 1500 RPM. Airflow should exist at outlet "A" with little or no airflow at outlet "B".
4. If valve does not operate as specified in steps 1), 2) and 3), replace valve. If airflow operates as specified, valve is okay. Reinstall hoses and clamps.

Scheme 89

Air Pump Resonator

Visually inspect for holes. Remove hoses and check for restricted ports. Replace resonator if holes or ports are restricted. Reconnect hoses, and install clamps.

Combination Air By-Pass/Air Control Valve

1. Disconnect hoses from outlets "A" and "B". (Scheme 90) Disconnect and plug vacuum line to port "D". With engine operating at 1500 RPM, airflow should be flowing from by-pass vents.
2. Reconnect vacuum line to port "D". Disconnect and plug vacuum line to port "S". Ensure vacuum is present in line to vacuum port "D". Accelerate engine to 1500 RPM. Airflow should be noted coming out of outlet "B". No airflow should be detected at outlet "A".
3. Apply 8-10 in. Hg vacuum to port "S". With engine operating at 1500 RPM, airflow should be noted coming out of outlet "A". If valve is bleed type, less air will flow from outlet "A" or "B" and main discharge will change when vacuum is applied to port "S".
4. If conditions in previous steps are not met, replace valve. If conditions are met, valve is okay. Reconnect hoses and vacuum lines.

Scheme 90

Dual Air Control Solenoid Valves

Function of each valve can be determined by externally energizing valve with vacuum lines attached. Check resistance of each solenoid. Resistance should be 51-108 ohms when checked at coil terminals. If resistance is not 51-108 ohms, solenoid should be replaced.

Air Injection Solenoid Valve

1. Vacuum control valve is normally closed when not energized. Valve may come with or without controlled bleed. Unstable idle may result from a leaking AIR solenoid valve. An electrical malfunction with valve should set a Diagnostic Trouble Code (DTC).
2. If unstable idle exists, remove vacuum hose from valve and plug hose. Warm engine to normal operating temperature. If idle becomes smoother, replace valve.

Vacuum Check Valve

Apply 16 in. Hg vacuum to check side of valve and trap. If vacuum remains greater than 15 in. Hg for 10 seconds, valve is okay. If vacuum drops faster, replace valve.

Vacuum Reservoir

When charged with 15-20 in. Hg vacuum, vacuum loss should not exceed .5 in. Hg in 60 seconds. If vacuum loss is faster, replace reservoir.

EXHAUST GAS RECIRCULATION (EGR)

Note. EVR solenoid has a constant internal leak. A small vacuum signal of less than one in. Hg vacuum is noticeable at idle.

Differential Pressure Feedback Electronic (DPFE) Sensor

Faults in DPFE sensor or circuit should set a trouble code. If no trouble code has been set, see CIRCUIT TEST DL in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section.

Electronic EGR (EEGR) 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 By-Pass Valve electrical connector (if equipped). 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.
3. Repair or replace EGR system if none of above occurs. Reconnect idle air by-pass valve electrical connector. Unplug and reconnect vacuum hose at EGR valve.

EGR Vacuum Regulator (EVR)

1. Faults in EVR or circuit should set a trouble code. See QUICK TEST in «TESTS W/CODES - EEC-IV»(ref-22952) article in the ENGINE PERFORMANCE section. If no trouble code has been set, see CIRCUIT TEST DN in «TESTS W/CODES - EEC-IV»(ref-22952) article for diagnostic procedures.
2. Remove EVR harness connector. Measure resistance across EVR terminals. Resistance should be 65-110 ohms. Set DVOM to 200-k/ohm scale. Measure resistance between each terminal and ground. Resistance should be 10,000 ohms or more. If resistance is not as specified in either test, replace solenoid.

Apply 16 in. Hg vacuum to check side of valve and trap. If vacuum remains greater than 15 in. Hg for 10 seconds, valve operation is normal. If vacuum does not remain greater than 15 in. Hg for 10 seconds, replace valve.

When charged with 15-20 in. Hg vacuum, vacuum loss should not exceed .5 in. Hg in 60 seconds. If vacuum loss is greater than specified, replace reservoir.

Canister Purge Regulator (CPR) Valve

With CPR valve de-energized, apply 5 in. Hg vacuum to source port. Valve should not pass air. Apply 9-14 volts to one electrical terminal, and ground other. Valve should open and pass air. If valve does not operate as described, replace valve.

1. Disconnect CANP solenoid harness connector. Set DVOM to 200-ohm scale. Measure resistance across CANP solenoid terminals. Resistance should be 40-90 ohms. If resistance is not as specified, replace CANP solenoid.
2. Disconnect vacuum hose at CANP solenoid on manifold vacuum side. Apply 16 in. Hg vacuum to manifold vacuum side of solenoid. CANP solenoid should hold vacuum for 20 seconds.
3. Faults in CANP solenoid or circuit should set a trouble code. See QUICK TEST in «TESTS W/CODES - EEC-IV»(ref-22952) article in the ENGINE PERFORMANCE section. If no trouble code has been set, see CIRCUIT TEST KD in «TESTS W/CODES - EEC-IV»(ref-22952) article for additional solenoid and circuit testing.

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.

Air Cleaner Temperature Sensor

Bring temperature of sensor to less than 75°F (24°C), and apply 8 in. Hg vacuum to source port. Duct door should close. If door does not close, replace sensor. Sensor will bleed off vacuum to allow duct door to open and let in fresh air at specific temperatures. See AIR CLEANER TEMPERATURE SENSOR OPENING table.

AIR CLEANER TEMPERATURE SENSOR OPENING

Air Control Door

When a vacuum of 8 in. Hg or more is applied to vacuum motor, door should stay in proper position for as long as vacuum is applied. If vacuum bleeds off and door returns to rest position, replace vacuum motor.

Wiring Diagram (5.0L Without E40D Or 4R70W - 1 Of 2). Scheme 91

Wiring Diagram (5.0L Without E40D Or 4R70W - 2 Of 2). Scheme 92

Wiring Diagram (5.0L With E40D - 1 Of 2). Scheme 93

Wiring Diagram (5.0L With E40D - 2 Of 2). Scheme 94

Wiring Diagram (5.0L With 4R70W - 1 Of 2). Scheme 95

Wiring Diagram (5.0L With 4R70W - 2 Of 2). Scheme 96

Wiring Diagram (5.8L - 1 Of 2). Scheme 97

Wiring Diagram (5.8L - 2 Of 2). Scheme 98