5.2l Efc System/testing Chrysler Fifth Avenue II

DESCRIPTION

The Electronic Fuel Control System (EFC) is used on all models. System consists of a Spark Control Computer (SCC), various engine sensors, a specially calibrated carburetor and a dual pick-up distributor. The purpose of the system is to maintain the ideal air/fuel ratio of 14.7:1 in almost all operating conditions.

SPARK CONTROL COMPUTER (SCC)

The SCC controls the entire ignition system. It is capable of igniting the fuel mixture according to different engine operating conditions during a run-drive period by delivering an infinite amount of variable electronic spark advance curves.

The SCC has a built-in microprocessor that continually receives input from different engine sensors to enable the computer to electronically retard or advance the ignition timing and adjust the air/fuel mixture to assure the most efficient fuel burn possible.

SENSORS

Engine control sensors supply the Spark Control Computer (SCC) with information needed to fire the spark plugs at the right time and change the air/fuel mixture. Spark advance provided by computer is determined by input factors from coolant temperature, engine RPM, and available manifold vacuum. Air/fuel mixture information comes from the oxygen sensor and carburetor idle stop switch.

Other sensors include, magnetic pick-up assembly, charge temperature sensor, vacuum transducer, distance/speed sensor, and detonation sensor.

FUEL CONTROL

Carburetors used include the Holley 6280 2-Barrel and the Rochester Quadrajet 4-Barrel used on police models only. Both models are equipped with an electronically-operated oxygen feedback solenoid. This solenoid meters the main fuel system of the carburetor and operates in parallel with the conventional fixed main metering jets. The computer controls the operation of the solenoid with electrical signals, in response to input from data sensors. (Scheme 272)and (Scheme 273).

Scheme 272

Scheme 273

When de-energized, the solenoid main metering orifice is fully uncovered, providing the richest mixture for any given airflow.

When the solenoid is energized by the computer, the solenoid main metering orifice is fully sealed. This solenoid position offers the leanest mixture within the carburetor for any given airflow.

Main system fuel is regulated between rich and lean mixture conditions by controlling the amount of time that the solenoid is energized and de-energized. The computer controls the duration of time that solenoid is energized in comparison to total time of solenoid operation.

This duration of time is determined by engine operating conditions and/or oxygen sensor signals. In this manner, the ideal air/fuel ratio can be constantly maintained.

ELECTRONIC THROTTLE CONTROL

The Electronic Throttle Control system and 2 electric timers are incorporated within the SCC. A solenoid, mounted on the carburetor, is energized whenever the air conditioning, rear window defogger or electric timers are activated. The 2 timers operate when the throttle is closed, providing a 2-second time delay, or after engine is started.

SPARK CONTROL

Spark control allows the computer to determine the exact instant that ignition is required. The computer eliminates the need for a vacuum advance unit or centrifugal advance weights. Spark control operates in one of the following modes

Start Mode (4-Bbl.)

During cranking, an electrical signal from the distributor "Start" pick-up coil is fed into the computer. This signal causes the computer to fire the spark plugs at a fixed amount of advance during engine cranking only. The amount of advance is determined by distributor position.

Run Mode (2-Bbl. & 4-Bbl.)

On 2-Bbl. models, the "Run" pick-up coil is the only pick-up coil used. This pick-up coil starts and runs the engine. The pick-up coil sends a reference signal to the computer. Timing is controlled by the computer, based upon information received by the data sensors. If this component fails, the vehicle will not run.

On 4-Bbl. models, once the engine starts, the "Run" pick-up coil sends a reference signal to the computer. Timing, however, is controlled by the computer, based upon information received by the data sensors. (Scheme 274)and (Scheme 275).

Spark timing and dwell cannot be adjusted in the run mode. If the computer fails, the system will go into the start mode. This enables the vehicle to be driven in for repair; but performance and fuel economy will be poor. If the start mode fails, the engine will not start or run.

On all models, the amount of spark advance is determined by engine speed and engine vacuum. However, when it happens depends upon the following conditions

1. Advance From Vacuum - Advance based upon engine vacuum is allowed by the computer when the carburetor switch is open. The amount of advance is programmed into the computer and is proportionate to the amount of vacuum and engine RPM.
2. Advance From Speed - Advance based upon engine speed (RPM) is allowed by the computer when the carburetor switch is open and the vacuum level is steady. This advance from speed is programmed into the computer, controlled by engine RPM, and will build at a slow rate. If the carburetor switch closes, advance from speed will be canceled.

DATA SENSORS

Each sensor furnishes electronic impulses to the SCC. The SCC computes ignition timing and air/fuel mixture ratio necessary to maintain proper engine operation. The function of each sensor is closely related to each of the other sensors. (Scheme 274)and (Scheme 275) for location of the data sensors.

Scheme 274

Scheme 275

Magnetic Pick-Up Assembly

The magnetic pick-up assemblies are located inside the distributor. All 2-Bbl. models use one pick-up coil assembly, a run pick-up coil assembly. All models with 4-Bbl. carburetor use 2 pick-up coils, a start pick-up coil and a run pick-up coil. The dual pick-up coils operate as follows

1. "Start" Pick-Up Coil (4-Bbl.) - Supplies a signal to SCC which will cause the spark plugs to fire at a fixed amount of advance during cranking only. This coil is permanently positioned in distributor and the amount of advance will be determined by distributor position. (Scheme 276)
2. "Run" Pick-Up Coil (2-Bbl. & 4-Bbl.) - On 2-Bbl. models, the "Run" pick-up coil is the only pick-up coil used. This pick -up coil starts and runs the engine. Timing is controlled by the computer, based upon information received by the data sensors.

On 4-Bbl. models, once engine begins to run, the start pick-up coil signal is by-passed and the run pick-up coil supplies advance information to SCC. (Scheme 276) The SCC then modifies ignition timing advance to reflect engine operating conditions reported by the other sensors.

Scheme 276

Coolant Temperature Sensor/Switch

The coolant temperature sensor/switch is located in the intake manifold. It informs the SCC when the engine has reached normal operating temperature. It prevents any changes from being made until such temperature is reached, permitting proper adjustment of the air/fuel ratio. The coolant temperature sensor/switch also controls the amount of ignition timing advance or retard when the engine is cold.

Vacuum Transducer

This sensor is mounted on the computer and provides the computer with a signal indicating the amount of engine vacuum. Engine vacuum is used by the computer to determine how much to advance or retard ignition timing and to change air/fuel mixture.

Carburetor Switch

Located on the end of idle stop, the carburetor switch informs the computer when the engine is at idle. When carburetor switch contacts throttle lever ground, the computer will cancel spark advance and prevent the air/fuel ratio from being adjusted.

Detonation Sensor

This sensor is mounted in the No. 2 branch of intake manifold and sends a low voltage signal to the SCC whenever engine knock is detected. The SCC then retards ignition timing a maximum of 20 degrees, the actual amount being proportional to strength and frequency of detonation. When the condition no longer exists, ignition timing is advanced to original value.

Oxygen Sensor

Located in the exhaust manifold, this sensor informs the computer of the amount of oxygen present in exhaust gases. The amount is proportional to mixture strength. The computer adjusts air/fuel ratio so that it will maintain operating efficiency of the 3-way catalyst system and the engine.

Charge Temperature Switch

This sensor is located in the No. 8 runner of intake manifold. The switch is closed when intake charge (air/fuel mixture) is less than 60°F (16°C). This controls EGR timer function, EGR valve operation and air injection switching system.

SPARK CONTROL COMPUTER

The computer is mounted on the air cleaner housing. It consists of a printed circuit board, which simultaneously receives signals from all data sensors and analyzes these signals to determine spark advance and air/fuel mixture. (Scheme 277) Incorporated within the computer are the electronics for the throttle control, EGR and air switching systems. After determining spark advance, the computer will operate the engine in one of the following modes

Open Loop Mode

During cold engine operation, the air/fuel ratio is controlled by information programmed into the computer by the manufacturer. Until normal operating temperature is reached, the air/fuel mixture will be fixed at a rich level to allow proper engine warm-up. During this mode of operation, air from the air pump is injected "upstream" in the exhaust manifold to assist in heating-up the oxygen sensor.

Closed Loop Mode

Once normal engine operating temperature is achieved, the air/fuel ratio is controlled by the computer based upon information received from the oxygen sensor. During this mode of operation, air from the air pump is injected "downstream" into the catalytic converter.

Scheme 277

EXHAUST GAS RECIRCULATION (EGR)

The electronic EGR system is incorporated within the SCC. This system prevents EGR flow until engine has reached normal operating temperature (after a predetermined length of time).

ELECTRONIC AIR SWITCHING

The electronic air switching system is incorporated within the SCC. This system directs the flow of air from the air pump either "upstream" (cold engine) or "downstream" after engine has reached operating temperature and a specified period of time has elapsed.

Carburetor switch is located on the end of the idle stop. It cancels spark advance and changes air/fuel ratio. Ensure carburetor switch contacts throttle lever ground when throttle is in closed or idle position only.

Note. DO NOT remove grease from either harness connectors or connector cavities in computer. The grease is used to prevent moisture from corroding the terminals. If there is not at least 1/8" of grease on bottom of computer connector cavities, apply a liberal amount of Mopar Multipurpose Grease (2932524) over entire end of plug before reinstalling.

Removal & Installation

Disconnect negative battery terminal. Disconnect 10-wire and 12-wire connectors from computer. Remove vacuum hose from vacuum transducer. Remove mounting screws from inside air cleaner and remove computer. To install, reverse removal procedure.

Note. Computer is not serviceable. DO NOT attempt to take it apart for any reason. Also, if the vacuum transducer becomes defective, entire computer must be replaced.

Remove bracket and switch assembly from carburetor. Disconnect electrical connector. To install, reverse removal procedure and adjust as necessary.

Disconnect electrical connector. Remove retaining screw, oxygen feedback solenoid and gasket. To install, reverse removal procedure.

Disconnect battery cable. Without pulling on wire, remove electrical lead at sensor. Using O 2 Sensor Socket (C-4589), remove sensor. To install, coat threads of new sensor with nickel-based anti-seize compound. DO NOT use graphite or other compounds. Install sensor and tighten to 20 ft. lbs. (27 N.m). Connect electrical connector and battery cable.

NO START TEST MENU

NO START TEST MENU

NO START TEST DESCRIPTION

A malfunction in the EFC system may result in engine surge, hesitation, rough idle and/or poor fuel economy. Before performing any tests, check all vacuum hoses and electrical wiring for proper routing and connections and check for exhaust and intake manifold leaks. If these are in order, proceed with testing.

In order to provide a more useful description in the article title menu, we have abbreviated the title of NO START TEST to NS. For example "NO START TEST NO. 1 - CHECKING FOR SPARK AT PLUG WIRES" has become "NS-1 - CHECKING FOR SPARK AT PLUG WIRES". This allows more information to be displayed while in the menu screen or while using the DISPLAY GRAPHICS ONLY function.

NS-1 - CHECKING FOR SPARK AT PLUG WIRES

1. Disconnect any spark plug wire and insert spark tester or an insulated screwdriver into terminal. If using screwdriver, hold screwdriver shaft about 1/4" from ground. Have an assistant crank engine.
2. There should be a good spark between screwdriver and ground. If there is spark, proceed to NS-2. If no spark, proceed to «NS-5»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__ns-5-ignition-coil-spark-check) .

NS-2 - CHECKING FOR FUEL IN CARBURETOR

1. Remove air cleaner cover. Open throttle several times by hand. Look for fuel spray from accelerator pump nozzle in carburetor throat. There should be fuel spraying from the accelerator pump nozzle while opening throttle.
2. If fuel spray tests okay, proceed to «NS-3»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__ns-3-checking-for-fuel-fouled) . If there is no fuel spray, proceed to «NS-9»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting) .

NS-3 - CHECKING FOR FUEL FOULED SPARK PLUGS

Remove spark plugs. Inspect spark plug tips for wet fuel. Spark plugs should be dry. If spark plugs are dry, proceed to NS-4 below. If spark plugs are wet with fuel, clean and reinstall.

NS-4 - ENGINE TIMING CHECK

1. Connect timing light to engine. Have an assistant crank engine while you watch timing marks. Timing should be between 0-16 degrees BTDC. If timing is okay, check valve timing and compression.
2. If timing is not okay, set timing to 10 degrees BTDC while cranking. Engine should start. If engine starts, set timing to specification. If engine does not start, check valve timing and compression.

NS-5 - IGNITION COIL SPARK CHECK

1. Disconnect secondary coil wire from distributor cap. Hold coil wire 1/4" from ground. Crank engine. There should be spark between coil wire and ground.
2. If there is spark, check for problem in distributor cap, rotor or secondary wires. Repair or replace as necessary. If no spark, check coil wire resistance. Resistance should be 250-600 ohms per INCH or 3000-7500 ohms per foot. If resistance is within specifications, proceed to NS-6. If resistance exceeds specifications, replace coil wire.

NS-6 - IGNITION COIL PRIMARY WINDINGS RESISTANCE CHECK

1. Ensure ignition is off. Connect an ohmmeter between ignition coil positive and negative terminals. Ohmmeter reading should be 1-2 ohms. If resistance is not within specifications, replace ignition coil.
2. If resistance is within specifications, disconnect coil secondary wire from coil. Connect ohmmeter to the coil negative terminal and the secondary terminal. Ohmmeter reading should be 9400-11,700 ohms.
3. If resistance is not within specifications, replace ignition coil. If resistance is okay, check coil with a load test. If coil is okay, proceed to NS-7A below.

Scheme 278

Scheme 279

1. Disconnect distributor "Run" pick-up coil connector. Connect an ohmmeter between terminals of the pick-up coil connector. Ohmmeter reading should be 150-900 ohms. If there is zero resistance, an open circuit or resistance is not within specifications, replace pick-up coil. (Scheme 278): "RUN" Pick-Up Coil Connector
2. If resistance is okay, reconnect distributor "Run" pick-up coil connector. Disconnect the computer 10-pin connector. Connect an ohmmeter between 10-pin connector cavities No. 5 and 9. Ohmmeter reading should be 150-900 ohms. (Scheme 279): Computer Harness 10-Pin Connector
3. If there is zero resistance, open circuit or not within specifications, replace pick-up coil. If resistance is okay, check distributor "Run" pick-up coil air gap. If okay, go to NS-7B below.

Scheme 280

1. Disconnect distributor start pick-up coil connector (large connector). Connect an ohmmeter between pick-up coil connector terminals. Ohmmeter reading should be 150-900 ohms. (Scheme 280): "START" Pick-Up Coil Connector
2. If there is zero resistance, open circuit or resistance not within specifications, replace pick-up coil. If resistance is okay, reconnect distributor start pick-up coil connector. Disconnect the computer 10-pin connector. Connect ohmmeter between 10-pin connector cavities No. 3 and 5.
3. Ohmmeter reading should be 150-900 ohms. If there is zero resistance, an open circuit or resistance not within specifications, replace pick-up coil. If resistance is okay, check distributor pick-up coil air gap. If okay, proceed to NS-8 below.

Scheme 281

Scheme 282

1. Turn ignition off. Disconnect computer 10-pin connector. Connect a voltmeter between 10-pin connector terminal No. 2 and ground. Turn ignition switch to the "RUN" position. Voltage reading should be within one volt of battery voltage. (Scheme 281): Using Voltmeter to Test Ignition Switch at 10-Pin Connector
2. If voltage is not as specified, repair open circuit in wire from ignition switch to cavity No. 2. If voltage is okay, turn ignition off. Connect ohmmeter to 10-pin connector cavity No. 10 and ground. Ohmmeter should show continuity. (Scheme 282): Using Ohmmeter to Test Ignition Switch at 10-Pin Connector
3. If no continuity exists, repair open circuit. If there is continuity, check terminals No. 2 and 10 to ensure they are not spread apart causing a poor connection. If connections are okay, replace computer.

Scheme 283

1. Connect fuel pump pressure gauge to fuel line at carburetor. Plug fuel return line at fuel filter. Crank engine for at least 10 seconds. Fuel pump pressure should be at least 2-6 psi.
2. If fuel pump pressure is okay, replace fuel filter. If fuel pressure is not within specifications, connect a vacuum gauge to fuel pump inlet line. With fuel line disconnected from carburetor, crank engine for at least 10 seconds. Vacuum gauge should read a minimum of 10 in. Hg vacuum. (Scheme 283): Testing Fuel Pump Pressure
3. If vacuum is not within specifications, replace fuel pump. If vacuum is okay, check for restricted or plugged fuel lines, fuel tank vent or in-tank filter.

COLD DRIVEABILITY TEST MENU

COLD DRIVEABILITY TEST MENU

COLD DRIVEABILITY TEST DESCRIPTION

In order to provide a more useful description on the menu screen, we have abbreviated the title of NO START TEST to NS. For example "COLD DRIVEABILITY TEST NO. 1 - CHOKE POSITION CHECK" has become "COLD DR-1 - CHOKE POSITION CHECK". This allows more information to be displayed while in the menu screen or while using the DISPLAY GRAPHICS ONLY function.

COLD DR-1 - CHOKE POSITION CHECK

1. Depress gas pedal to set choke. Remove air cleaner cover. Check choke plate and fast idle cam position. Choke plate should be fully closed and fast idle cam set to highest step.
2. If choke plate is not fully closed or cam not in position, check choke plate for binding or sticking. Repair choke plate or linkage as necessary. If choke plate position and cam are okay, proceed to «COLD DR-2A»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__cold-dr-2a-choke-vacuum-kick) for 2-bbl or «COLD DR-2B»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__cold-dr-2b-choke-valve-angle) for 4-bbl.

COLD DR-2A - CHOKE VACUUM KICK CHECK (2-BBL.)

1. Remove air cleaner assembly. Position fast idle screw on highest step of fast idle cam. Remove vacuum hose from choke vacuum kick diaphragm. Connect a vacuum pump and apply 15 in. Hg vacuum to the diaphragm. Measure clearance between top of choke plate and air horn.
2. Vacuum should remain at 15 in. Hg and choke plate should be set to .130". If vacuum does not remain at 15 in. Hg, replace vacuum kick diaphragm. Adjust vacuum kick as necessary. If vacuum remains constant, proceed to «COLD DR-3»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__cold-dr-3-air-cleaner-heated) .

COLD DR-2B - CHOKE VALVE ANGLE CHECK (4-BBL.)

1. Remove air cleaner assembly. Attach a rubber band between the intermediate choke shaft and air horn. Open throttle to allow choke valve to close. Install choke angle gauge to choke plate. Rotate degree scale until pointer is set to zero. Center leveling bubble.
2. Rotate scale to 25 degree angle. Disconnect vacuum hose from choke vacuum diaphragm. Connect a vacuum pump to choke vacuum diaphragm. Apply 18 in. Hg vacuum. Choke valve should open and the angle gauge centering bubble should be level.
3. If choke valve opens and centering bubble is level, proceed to «COLD DR-3»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__cold-dr-3-air-cleaner-heated) . Adjust choke valve angle as necessary. If choke valve does not open, replace choke diaphragm or repair linkage as necessary.

COLD DR-3 - AIR CLEANER HEATED AIR INTAKE SYSTEM

1. Disconnect air duct from air cleaner snorkel. Disconnect vacuum supply hose to heated air intake system air temperature sensor. Connect vacuum pump to the air temperature sensor and apply 15 in. Hg vacuum to the sensor. Vacuum should build up to 15 in. Hg and close the heated air door when air temperature is below 70°F (21°C). Vacuum should bleed down slowly, opening the heated air door. NOTE: Models equipped with 2-Bbl. carburetors use a vacuum delay valve at the heated air door vacuum diaphragm. This delays opening of the door when vacuum bleeds off.
2. If vacuum builds up, but heated air door does not close, repair or replace door as necessary. If vacuum does not build up or bleed down, replace the air temperature sensor. If vacuum builds up and bleeds down, but heated air door does not open, repair or replace door as necessary.
3. If vacuum builds up, closes the heated air door and then bleeds down, proceed to «COLD DR-4»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting) on 2-Bbl. models. On 4-Bbl. models, remove vacuum hose from vapor containment door diaphragm. Connect a vacuum pump to the diaphragm and apply 15 in. Hg vacuum. Vacuum should hold and door should be open.
4. If vacuum does not hold or door is not open, repair or replace as necessary. If vacuum holds and door is open, reconnect hose to vapor containment door diaphragm. Remove vacuum supply hose from vapor containment door vacuum delay valve. Connect vacuum pump to delay valve and apply 15 in. Hg vacuum. Release vacuum.
5. Vapor containment door should open when vacuum is applied and close within 40 seconds after vacuum is released. If door does not close or open, replace vacuum delay valve. If door closes and opens okay, proceed to COLD DR-4 below.

Scheme 284

1. Disconnect both connectors from the computer. Connect an ohmmeter between 10-pin connector cavity No. 9 and 12-pin connector cavity No. 10. Ohmmeter reading should be as shown in the «CHARGE TEMPERATURE SENSOR RESISTANCE»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting) table below. CHARGE TEMPERATURE SENSOR RESISTANCE Temperature °F (°C) Ohms -40 to 20 (-40 to -7) 382,000-22,000 50-100 (10-38) 36,000-3300 140-245 (60-118) 3900-176
2. If resistance checks okay, proceed to «COLD DR-5»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting). If resistance is not within specifications, disconnect the charge temperature sensor connector. Connect an ohmmeter between the charge temperature sensor terminals. Resistance should be as shown in the «CHARGE TEMPERATURE SENSOR RESISTANCE»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting) table. (Scheme 284): Measuring Charge Temperature Sensor Connector Resistance
3. If resistance is okay, repair wiring between computer and sensor for a short or open circuit. If resistance is not within specifications, replace charge temperature sensor.

Measuring Charge Temperature Sensor Resistance. Scheme 285

Scheme 286

Scheme 287

Scheme 288

Scheme 289

Scheme 290

Scheme 291

1. Remove air cleaner lid. Set choke. Start engine and observe choke plate position. Choke plate should open part way. If choke plate is not opening properly, check vacuum supply to choke vacuum kick. If choke plate opened properly, connect a voltmeter between the choke heater wire at choke control switch and ground.
2. If air temperature is less than 55°F (13°C), voltage reading should be 5-9 volts. If air temperature is greater than 80°F (27°C), voltage reading should be within one volt of battery voltage. If voltage is not within specification, go to step 5). On 2-Bbl. models, if voltage reading is within specifications, turn ignition off. Disconnect wire from choke control that goes to electric choke heater. (Scheme 286): Measuring Choke Control Switch Voltage
3. Connect an ohmmeter between choke heater wire and choke heating element retaining screw. Reading should be 4-12 ohms. If resistance is not within specification, replace choke heating element. If resistance is okay, proceed to «COLD DR-6»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting). (Scheme 287): Measuring Choke Heater Wire Resistance
4. On 4-Bbl. models, if voltage reading is okay, connect voltmeter to choke heating element harness connector and ground. There should be voltage present. If there is voltage at heater, proceed to «COLD DR-6»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting). If voltage reading is not okay, repair choke control switch wiring for an open circuit. (Scheme 288): Checking Heating Element Harness Connector for Voltage
5. If voltage reading in step 2) was not as specified, connect voltmeter to choke control switch ignition feed wire and ground. Voltage reading should be within one volt of battery voltage. If voltage reading is okay, replace choke control switch. (Scheme 289): Checking For Voltage to Choke Control Switch
6. If voltage is not within specification, turn ignition off. Disconnect oil pressure switch connector. Connect voltmeter to engine harness connector at oil pressure switch terminal "C" and ground. Turn ignition switch to the "RUN" position. Voltage should be within one volt of battery voltage. (Scheme 290): Measuring Voltage at Oil Pressure Switch Connector
7. If voltage is not within specification, repair harness to ignition switch for an open circuit. If voltage is within specification, turn ignition off. Disconnect ignition feed wire from choke control switch. Connect an ohmmeter between engine harness connector at the oil pressure switch terminal "A" and choke control switch wire. (Scheme 291): Checking for Continuity Between Oil Pressure Switch Connector & Choke Control Switch
8. Ohmmeter should show continuity. If there is continuity, replace oil pressure switch. If no continuity, repair harness for an open circuit.

Scheme 292

Scheme 293

Scheme 294

1. Disconnect vacuum hose from EGR valve. Connect vacuum gauge to the vacuum hose. Start engine. Slowly increase engine speed. Vacuum reading should be zero with the engine temperature less than 70°F (21°C) on 2-Bbl. models and less than 50°F (10°C) on 4-Bbl. models. If there is NO vacuum, proceed to «COLD DR-7»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__cold-dr-7-spark-plug-check).
2. If there is vacuum, connect voltmeter to the EGR vacuum solenoid (Gray wire) and ground. Observe voltmeter reading. Voltage should be 0-1 volts with the engine temperature less than 70°F (21°C) on 2-Bbl. models and less than 50°F (10°C) on 4-Bbl. models. (Scheme 292): Testing EGR Vacuum Solenoid (Gray Wire)
3. If voltage is okay, connect voltmeter to EGR vacuum solenoid (Blue wire) and ground. Voltage reading should be within one volt of battery voltage. If voltage reading is okay, replace EGR solenoid. If zero volts, repair wiring to the ignition switch for an open circuit. (Scheme 293): Testing EGR Vacuum Solenoid (Blue Wire)
4. If voltage reading in step 2) is greater than one volt, turn ignition off. Disconnect computer 12-pin connector. Connect a voltmeter to 12-pin connector cavity No. 7 and ground. Turn the ignition switch to the "RUN" position. Voltmeter reading should be within one volt of battery voltage. (Scheme 294): Testing EGR System at the 12-Pin Connector
5. If voltage is within specifications, check terminal in 12 pin connector cavity No. 7 to ensure it is not spread apart causing a poor connection. If connections are okay, replace computer. If there is zero volts, repair wiring to cavity No. 7 for an open circuit to the EGR vacuum solenoid.

COLD DR-7 - SPARK PLUG CHECK

Remove spark plugs. Spark plugs should be dry. If spark plugs are wet with fuel, clean and reinstall plugs. Check for fuel in crankcase. Change oil and filter if necessary. Go to COLD DR-8 below.

COLD DR-8 - SECONDARY IGNITION CHECK

Turn all lights and accessories off. Connect a suitable engine analyzer to the engine. Start engine. Check secondary ignition pattern. Check ignition coil output. Open circuit secondary ignition voltage should be at least 25,000 volts. If scope pattern is okay, proceed to COLD DR-9 below. If scope pattern is not okay, repair secondary ignition as necessary.

Scheme 295

Scheme 296

1. Disconnect the 12-pin connector from the computer. Connect a voltmeter to connector cavity No. 4 and ground. Voltmeter reading should be within one volt of battery voltage. If there is zero volts, repair open circuit in wiring to connector cavity No. 4. (Scheme 295): Checking For Voltage to Computer
2. If voltage is okay, check terminal in connector cavity No. 4 to ensure it is not spread apart causing a poor connection. Connect a voltmeter to oxygen solenoid connector (Green wire) and ground. Connect a tachometer and start engine. Voltage reading should be a steady 7-14 volts.
3. If voltage reading is greater than zero volts, but less than 7 volts, replace the computer. If voltage is 0-1 volt, turn the ignition off. Disconnect the computer 12-pin connector. Turn the ignition switch to the "RUN" position. Voltage reading should be within one volt of battery voltage.
4. If voltage is okay, replace the computer. If there is still zero volts, connect a voltmeter to the O 2 solenoid connector Blue or Tan wire and ground. Voltmeter reading should be within one volt of battery voltage. If voltage is okay, replace the O 2 solenoid. If voltage is still zero, repair Blue or Tan wire for an open circuit to the ignition switch.
5. If voltage in step 2) is okay, ground O 2 solenoid (Green wire) using a jumper lead. Engine speed should drop. If engine speed does not drop, replace O 2 solenoid. If engine speed drops, proceed to COLD DR-10 below.

Scheme 297

1. Disconnect bowl vent hose from the vapor canister. Blow lightly into hose. Air should flow through hose. If air does not flow through the hose, check for a restricted/plugged hose or repair bowl vent. (Scheme 297): Checking Bowl Vent Valve
2. If airflow is okay, start engine. Blow lightly into hose. Air should not flow through hose. If air flows through hose, repair bowl vent valve. If air does not flow through hose, go to «COLD DR-11»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting) (4-Bbl. models) or «COLD DR-12»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__cold-dr-12-ignition-timing-check) (2-Bbl. models).

Note. Models equipped with 2-Bbl. carburetors use an electric valve. Models equipped with 4-Bbl. carburetors use an external valve that closes with air pump pressure.

Scheme 298

Scheme 299

Scheme 300

1. Start and run engine until normal operating temperature is reached. Raise engine speed to 1100 RPM. Disconnect "Start" pick-up coil connector at the distributor (larger connector). Engine should stay running. If engine stays running, proceed to «COLD DR-12»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__cold-dr-12-ignition-timing-check). (Scheme 298): Location of "START" Pick-Up Connector
2. If engine stalls, disconnect the "Run" pick-up coil. Connect an ohmmeter between the connector terminals. Ohmmeter reading should be 150-900 ohms. If resistance is within specifications, reconnect the distributor pick-up coil connector. Disconnect the computer 10-pin connector. (Scheme 299): Testing "RUN" Pick-Up Coil
3. Connect an ohmmeter between 10-pin connector cavities No. 5 and 9. Ohmmeter reading should be 150-900 ohms. If resistance is okay, remove distributor cap. Measure "Run" pick-up coil air gap. Air gap should be.012" (.3 mm). Adjust air gap as necessary. (Scheme 300): View of Computer Harness 10-Pin Connector
4. If air gap is okay, check terminals in cavities No. 5 and 9 to ensure they are not spread apart causing a poor connection. If connections are okay, replace computer. If resistance in step 2) is not to specifications, replace the "Run" pick-up coil.

Location of the "RUN" Pick-Up Coil. Scheme 301

COLD DR-12 - IGNITION TIMING CHECK

1. Connect a tachometer and timing light to the engine. Ground the carburetor switch. Start and run engine until normal operating temperature is reached. Raise engine speed to more than 1100 RPM. Disconnect and plug vacuum hose to the computer (2-Bbl. models).
2. Engine speed should be within specifications when setting timing. Adjust idle speed to 450-650 RPM (2-Bbl. models) or 550-750 RPM (4-Bbl. models). Basic timing should be within 2 degrees of specification shown on vehicle emission label. Adjust timing if necessary.
3. Remove jumper lead from carburetor ground switch. Disconnect and plug vacuum hose to the computer (4-Bbl. models). Connect a vacuum pump to the computer. Apply 16 in. Hg vacuum. Raise engine speed to 2000 RPM. Timing should be within 4 degrees of specification. See the «SPARK ADVANCE SPECIFICATIONS»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting) table below. SPARK ADVANCE SPECIFICATIONS (1) Application Computer No. Advance Spark 5.2L (2-Bbl.) 4379484 46°BTDC 5.2L (2-Bbl.) 4379682 46°BTDC 5.2L (4-Bbl.) 4379226 38°BTDC 5.2L (4-Bbl.) 4379228 38°BTDC (1) Specifications are +/- 4 degrees.
4. If spark advance is not within specifications, replace the computer. If spark advance is okay, return engine to idle. Disconnect vacuum pump from the computer. Connect a vacuum gauge to the computer vacuum supply hose. Gauge should read manifold vacuum. If vacuum reading is not okay, check and repair vacuum supply from carburetor. If vacuum reading is okay, proceed to «COLD DR-13»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__cold-dr-13-idle-rpm-check) below.

COLD DR-13 - IDLE RPM CHECK

1. Turn all lights and accessories off. Place transmission in Neutral. Set parking brake. Start and run engine until normal operating temperature is reached. Ground the carburetor switch with a jumper lead. Disconnect and plug vacuum hose to the EGR valve.
2. Disconnect and plug 3/16" vacuum hose from vapor canister. Remove PCV valve from valve cover and allow it to draw outside air. On 2-Bbl. models, disconnect and plug vacuum hose from the computer. Disconnect the carburetor 4-pin connector and remove the Green wire to the O 2 solenoid from the connector.
3. Reconnect the 4-pin connector. Start and run engine for 4 minutes before proceeding. On 4-Bbl. models, connect a voltmeter to the O 2 solenoid (Green wire) and ground. Disconnect and ground wire from the O 2 sensor using a jumper lead. Start engine and let idle until voltmeter reading is a steady 7-13 volts. This may take up to 4 minutes.
4. On all engines, tachometer reading should be within specifications shown on emissions label. Set idle RPM to specifications as necessary. Tee in propane supply into heated air temperature sensor vacuum hose. Open propane valve and meter in propane until maximum RPM is obtained. Engine speed should increase 60 RPM (2-Bbl. models) or 50 RPM (4-Bbl. models) +/- 50 RPM.
5. Open throttle and position fast idle adjusting screw on 2nd highest step of the fast idle cam. Fast idle speed should be set to specifications +/- 100 RPM. See «FAST IDLE SPEED»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting) table. Adjust fast idle speed to specifications as necessary.

FAST IDLE SPEED

COLD DR-14 - VERIFICATION CHECKS

At this point, test procedures have determined that all engine control systems are operating correctly and are not the cause of the driveability problem. Check the following as possible causes

1. Check for at least 13 in. Hg engine vacuum in Neutral.
2. Check engine valve timing.
3. Check engine compression.
4. Check engine cooling system.
5. Check exhaust system for restrictions.
6. Check engine PCV system for free flow.
7. Check intake manifold heat crossover for plugging.
8. Check fuel pump pressure, volume and vacuum.
9. Check torque converter stall speed.
10. Check power brake booster for internal vacuum leaks.
11. Check for fuel contamination.
12. Check carburetor for circuit contamination and proper calibration.
13. Check Technical Service Bulletins that may apply to vehicle.

WARM DRIVEABILITY TEST MENU

WARM DRIVEABILITY TEST MENU

WARM DRIVEABILITY TEST DESCRIPTION

In order to provide a more useful description on the menu screen, we have abbreviated the title of NO START TEST to NS. For example "WARM DRIVEABILITY TEST NO. 1 - CARBURETOR SWITCH CHECK" has become "WARM DR-1 - CARBURETOR SWITCH CHECK". This allows more information to be displayed while in the menu screen or while using the DISPLAY GRAPHICS ONLY function.

WARM DR-1 - CARBURETOR SWITCH CHECK

1. With engine at normal operating temperature, disconnect computer 10-pin connector. Connect an ohmmeter between 10-pin connector cavity No. 7 and ground. Open and close the throttle while watching ohmmeter. Ohmmeter reading should show continuity, with no resistance, when the throttle is closed and no continuity when the throttle is open.
2. If there is continuity when the throttle is open, repair wire to connector cavity No. 7 for a short to ground. If there is continuity with resistance when the throttle is closed, check carburetor switch for corrosion. Clean as necessary.
3. If there is no continuity when the throttle is closed, repair wire to connector cavity No. 7 for an open circuit to the carburetor switch. If continuity checks okay, proceed to «WARM DR-2»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting) .

Testing Carburetor Switch. Scheme 302

Scheme 303

1. Disconnect both connectors from computer. Connect an ohmmeter between 10-pin connector cavity No. 9 and 12-pin connector cavity No. 10. Ohmmeter reading should be 176-3900 ohms. If resistance is okay, proceed to «WARM DR-3»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting). If resistance is not okay, disconnect charge temperature sensor connector. (Scheme 303): Testing Charge Temperature Sensor Wiring Harness Resistance
2. Connect an ohmmeter between charge temperature switch terminals. Ohmmeter reading should be 176-3900 ohms. If resistance is okay, repair wiring between computer and sensor for an open/short circuit. If resistance is not within specifications, replace charge temperature switch.

Scheme 304

1. Remove air cleaner lid. Start engine. Observe choke plate position. Choke plate should be fully open. If choke position is okay, proceed to «WARM DR-4»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__warm-dr-4-start-to-run-pick-up-coil) for 4-Bbl or «WARM DR-5»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting) for 2-Bbl. If choke position is not okay, connect a voltmeter to choke heater wire at choke control switch terminal and ground. Voltage reading should be within one volt of battery voltage. see scheme 34: Measuring Choke Control Switch Voltage
2. On 2-Bbl. models, if voltage reading is within specifications, turn ignition off. Disconnect wire from choke control that goes to electric choke heater. Connect an ohmmeter between choke heater wire and choke heating element retaining screw. Ohmmeter reading should be 4-12 ohms. If resistance is not within specification, replace choke heating element. If resistance is okay, check and repair choke linkage for sticking or binding. If voltage reading is not within specification, go to step 4). see scheme 35: Checking Heating Element Harness Connector for Voltage
3. On 4-Bbl. models, if voltage reading is within specification, connect voltmeter to choke heating element harness connector and ground. Voltage reading should be within one volt of battery voltage. If voltage is okay, check choke linkage for binding. If choke linkage is okay, replace the choke heating element. If voltage is not okay, repair open circuit in wiring to the choke control switch. If voltage reading is not within specification, go to next step. see scheme 36: Measuring Choke Heater Wire Resistance
4. Connect voltmeter to ignition feed wire connector of choke control switch and ground. Voltage reading should be within one volt of battery voltage. see scheme 37: Checking For Voltage to Choke Control Switch
5. If voltage is within specifications, replace choke control switch. If voltage is not within specifications, turn ignition off. Disconnect oil pressure switch connector. Connect voltmeter to engine harness connector at oil pressure switch terminal "C" and ground. see scheme 38: Measuring Voltage at Oil Pressure Switch Connector
6. Turn ignition switch to the "RUN" position. Voltage should be within one volt of battery voltage. If voltage is not within specification, repair harness to ignition switch for an open circuit. If voltage is within specification, disconnect ignition feed wire from choke control switch. (Scheme 304): Checking for Continuity Between Oil Pressure Switch Connector & Choke Control Switch
7. Connect an ohmmeter between engine harness connector at oil pressure switch terminal "A" and choke control switch wire. Ohmmeter should show continuity. If there is continuity, replace oil pressure switch. If there is no continuity, repair harness for an open circuit.

WARM DR-4 - START-TO-RUN PICK-UP COIL TRANSFER CKT (4-BBL)

1. Start engine. Raise engine speed to 1100 RPM. Disconnect "Start" pick-up coil connector at distributor (larger connector). Engine should stay running. If engine stays running, go to «WARM DR-5»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting). see scheme 40: Location of "START" Pick-Up Connector
2. If engine stalls, disconnect the "Run" pick-up coil (smaller connector). Connect an ohmmeter between the connector terminals. Ohmmeter reading should be 150-900 ohms. If resistance is not within specification, replace "Run" pick-up coil. If resistance is within specifications, reconnect the distributor pick-up coil connector. Disconnect the computer 10-pin connector. see scheme 41: Testing "RUN" Pick-Up Coil
3. Connect an ohmmeter between 10-pin connector cavities No. 5 and 9. Ohmmeter reading should be 150-900 ohms. If resistance is okay, remove distributor cap. Measure "Run" pick-up coil air gap. Air gap should be.012" (.3 mm). Adjust air gap as necessary. see scheme 42: View of Computer Harness 10-Pin Connector
4. If air gap is okay, check terminals in cavities No. 5 and 9 to ensure they are not spread apart causing a poor connection. If connections are okay, replace computer.

Scheme 305

Scheme 306

Scheme 307

Scheme 308

Scheme 309

Scheme 310

Scheme 311

1. With engine at normal operating temperature, let engine idle for one minute. While observing EGR valve stem, raise engine speed to more than 2500 RPM for more than 5 seconds. As engine speed increases, EGR valve stem should move upward. If EGR valve stem moves upward, go to next step. If EGR valve stem does not move, go to step 4).
2. Connect a tachometer to engine. Disconnect EGR vacuum line. Connect a vacuum pump to EGR valve. Slowly apply vacuum to EGR valve. Engine speed should decrease with 3-5 in. Hg vacuum applied and continue to drop as more vacuum is applied to EGR valve. If engine speed decreases, on 4-Bbl. models, go to «WARM DR-6»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__warm-dr-6-secondary-ignition-system), on 2-Bbl. models, go to next step. If engine speed does not decrease until 5 in. Hg vacuum or more is applied to EGR valve, replace EGR valve.
3. With engine running, disconnect manifold vacuum line from vacuum bleed-off valve and plug hose. Connect a vacuum pump to bleed-off valve nipple. Apply 25 in. Hg vacuum. Raise engine speed to 2500 RPM for 5 seconds. As engine speed is increased, EGR valve stem should not move. If EGR valve stem does not move, go to «WARM DR-6»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__warm-dr-6-secondary-ignition-system). If EGR valve stem moves upward, replace vacuum bleed-off valve. (Scheme 305): Disconnecting Manifold Vacuum Line
4. Disconnect vacuum hose from EGR valve. Connect a vacuum gauge to EGR vacuum hose. Raise engine speed to 2500 RPM for 5 seconds. As engine speed is increased, vacuum gauge reading should increase. If vacuum gauge reading increases, replace EGR valve. If vacuum gauge reading does not increase, on 2-Bbl. models, go to next step, on 4-Bbl. models go to step 7).
5. Disconnect EGR signal hose from vacuum bleed-off valve. Plug vacuum hose. Reconnect vacuum hose to EGR valve. Raise engine speed to 2500 RPM for 5 seconds. As engine speed is increased, EGR valve stem should move upward. If EGR valve stem moves upward, replace vacuum bleed-off valve. If EGR valve stem does not move upward, on California models, go to step 7), on Federal models, go to next step. (Scheme 306): Disconnecting EGR Signal Hose
6. Disconnect vacuum hose from White side of EGR vacuum delay valve. Connect a vacuum gauge to vacuum delay valve vacuum hose. Raise engine speed to 2500 RPM. As engine speed is increased, reading on vacuum gauge should increase. If vacuum gauge reading increased, replace EGR vacuum delay valve. If vacuum gauge reading did not increase, go to next step.
7. Disconnect bottom hose from EGR vacuum solenoid. Connect a vacuum gauge to EGR vacuum solenoid. Raise engine speed to 2500 RPM. As engine speed is increased, reading on vacuum gauge should increase. If vacuum gauge reading increases, repair vacuum hose to EGR valve. If vacuum gauge reading did not increase, go to next step. (Scheme 307): Disconnecting Bottom hose From EGR Vacuum Solenoid
8. Remove top hose from EGR vacuum solenoid. Connect a vacuum gauge to EGR vacuum solenoid. Raise engine speed to 2500 RPM. As engine speed is increased, reading on vacuum gauge should increase. If vacuum gauge reading increases, go to step 11). If vacuum gauge reading does not increase, on 2-Bbl. models, repair vacuum supply from carburetor, on 4-Bbl. models, go to next step. (Scheme 308): Disconnecting Top hose From EGR Vacuum Solenoid
9. Disconnect vacuum hose connector from EGR amplifier. Connect a vacuum gauge to middle vacuum hose on connector. Slowly increase engine speed. As engine speed increases, vacuum gauge reading should increase. If vacuum gauge reading increased, go to next step. If vacuum gauge reading does not increase, repair vacuum supply from carburetor. (Scheme 309): Disconnecting Vacuum Hose From EGR Amplifier
10. Connect a vacuum gauge to top vacuum hose on EGR amplifier vacuum hose connector. Vacuum gauge should read manifold vacuum. If vacuum gauge reading is okay, replace EGR amplifier. If vacuum gauge reading is not okay, repair vacuum supply from intake manifold. (Scheme 310): Testing EGR Amplifier
11. Connect voltmeter to Gray wire of EGR vacuum solenoid and ground. Voltmeter should read within one volt of battery voltage. If voltage reading is okay, replace vacuum solenoid assembly. If voltage reading is 0-1 volt, go to next step. (Scheme 311): Testing EGR Vacuum Solenoid
12. Turn engine off. Disconnect computer 12-pin connector. Turn ignition switch to "RUN" position. Voltmeter reading should be within one volt of battery voltage. If voltmeter reading is okay, replace computer. If voltmeter reading is still 0-1 volt, repair Gray wire for a short to ground.

WARM DR-6 - SECONDARY IGNITION SYSTEM CHECK

Turn all lights and accessories off. With engine at normal operating temperature, connect a suitable engine analyzer to the engine. Start engine and let engine speed stabilize for 2 minutes. Check secondary ignition pattern. Check ignition coil output. Open circuit secondary ignition voltage should be at least 25,000 volts. If secondary ignition voltage is okay, go to WARM DR-7 below.

Scheme 312

Scheme 313

Scheme 314

Scheme 315

1. Disconnect downstream air hose from air switching valve. Start engine and wait 4 minutes. There should be air coming out of air switching valve downstream air port. If there is air flowing from port, proceed to «WARM DR-8»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting). (Scheme 312): Location of Downstream Air Hose
2. If there is no air flowing from the port, disconnect upstream air hose from the air switching valve. There should be air flowing from the air switching valve upstream port. If there is no air flowing from the port, repair or replace the air pump. (Scheme 313): Location of Upstream Air Hose
3. If there is air flowing from the port, disconnect vacuum hose from air switching valve and connect a vacuum gauge to the hose. Vacuum reading should be zero in. Hg vacuum. If vacuum reading is as specified, replace air switching valve. If there is vacuum, connect a voltmeter to air switching solenoid (Green wire) and ground. (Scheme 314): Testing Air Switching Solenoid
4. Voltage reading should be within one volt of battery voltage. If voltage reading is okay, replace vacuum solenoid assembly. If there is 0-1 volt, turn the ignition off. Disconnect computer 12 pin connector. Connect voltmeter to connector cavity No. 12 and ground. Turn ignition switch to the "RUN" position. (Scheme 315): Testing Air Switching Wiring Harness
5. Voltage reading should be within one volt of battery voltage. If voltage is okay, replace computer. If there is still 0-1 volt, repair the Green wire for a short to ground.

Scheme 316

1. Disconnect bowl vent hose from canister. Blow lightly into hose. Air should flow through hose. If air does not flow through hose, check for a restricted hose and/or repair the bowl vent. (Scheme 316): Location of Bowl Vent Hose Nipple on Canister
2. If air flows through hose, start the engine. Blow lightly into hose. Air should not flow through hose. If air does not flow through hose, proceed to «WARM DR-9»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting). If air flows through hose, repair bowl vent.

Note. Models equipped with 2-Bbl. carburetors use an electric bowl vent valve. Models equipped with 4-Bbl. carburetors use an external valve that closes with air pump pressure.

Scheme 317

Scheme 318

Scheme 319

Scheme 320

1. Disconnect 12-pin connector from computer. Connect a voltmeter to connector cavity No. 4 and ground. Voltage reading should be within one volt of battery voltage. If there is zero volts, repair wiring to connector cavity No. 4 for an open circuit to the battery. (Scheme 317): Testing Oxygen (O2) System Harness
2. If voltage reading is okay, check terminal in connector cavity No. 4 to ensure it is not spread apart causing a poor connection. Connect voltmeter to the O 2 solenoid connector (Green wire) and ground. Disconnect and plug the vacuum hose from the computer. (Scheme 318): Location of Oxygen (O2) Solenoid Test Position
3. Connect a vacuum pump to the computer and apply 14 in. Hg vacuum. Start engine and wait 4 minutes. Raise engine speed to 2000 RPM. Voltage reading should be varying between 4-14 volts. If voltage reading is okay, remove air cleaner lid. Close choke plate. Voltage reading should drop toward zero. If voltage reading is zero volts, go to next step. If voltage reading is 1-3 volts, go to step 12).
4. If voltage drops, connect a tachometer to engine. Connect a jumper lead to O 2 solenoid (Green wire) and ground. Engine speed should drop. If engine speed drops, proceed to «WARM DR-10»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting). If engine speed did not drop, replace O 2 solenoid.
5. If voltage reading in step 3) does not drop, disconnect O 2 sensor connector. Hold O 2 sensor harness terminal in one hand and touch battery positive with the other hand. Voltage should drop. If voltage drops, replace O 2 sensor. (Scheme 319): Testing Oxygen (O2) Sensor (Battery Positive)
6. If voltage does not drop, return engine to idle. Turn ignition off. Disconnect 12-pin connector from computer. Connect a voltmeter to the connector cavity No. 11 and ground. Turn the ignition switch to the "RUN" position. Voltage reading should be within one volt of battery voltage. (Scheme 320): Testing Oxygen (O2) System For Voltage at 12-Pin Connector
7. If voltage is okay, check the terminal in connector cavity No. 4 to ensure it is not spread apart causing a poor connection. If terminal is okay, replace the computer. If there is zero volt, repair wiring in connector cavity No. 11 for an open circuit to the carburetor 4-pin connector.
8. If there is zero volt in step 3), turn the ignition off. Disconnect the 12-pin connector from the computer. Turn the ignition switch to the "RUN" position. Voltage reading should be within one volt of battery voltage. If voltage reading is okay, replace the computer.
9. If there is 0-1 volt, turn the ignition off. Disconnect the O 2 solenoid connector. Connect an ohmmeter between the O 2 solenoid Tan and Green wires (between the solenoid terminals on 4-Bbl. models). The ohmmeter should show some resistance. NOTE: The amount of resistance is unimportant. Just ensure there is some resistance.
10. If there is an open circuit, replace the O 2 solenoid. If there is resistance, connect a voltmeter to the O 2 solenoid connector (Blue wire) and ground. Turn the ignition switch to the "RUN" position. Voltage reading should be within one volt of battery voltage.
11. If voltage reading is okay, repair the Green wire to the computer for a short to ground. If voltage reading is not okay, repair the Blue wire for an open circuit to the ignition switch.
12. If there is 1-3 volts in step 3), disconnect the PCV valve hose and plug it with your finger. Gradually allow air to enter PCV hose. Voltage reading should increase. If voltage increases, check for fuel contamination in the crankcase. Change oil and filter as necessary. If there is fuel contamination in the crankcase, repair the carburetor.
13. If voltage does not increase, disconnect the O 2 sensor connector. Hold the O 2 sensor harness terminal in one hand and touch the battery positive with the other hand. Voltage should increase. If voltage increases, replace O 2 sensor. If voltage does not increase, replace computer.

Testing Oxygen (O2) Sensor (Battery Negative). Scheme 321

Scheme 322

Scheme 323

Scheme 324

Scheme 325

1. Turn all lights and accessories off. Position air cleaner aside so that idle control solenoid is visible. Have an assistant start the engine while you observe the solenoid plunger. Open and close the throttle if necessary to activate the solenoid.
2. Solenoid plunger should move out and hold the throttle open for a specified length of time. See «ELECTRONIC THROTTLE CONTROL»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting) table. After specified length of time, solenoid should allow throttle to return to curb idle position. If plunger extends, but does not retract as specified, go to step 7). If plunger does not operate, go to step 3). If plunger operation is okay, go to step 8), 13) or 17) as equipped. ELECTRONIC THROTTLE CONTROL Computer No. (1) Throttle Control 4379484 & 4379682 120 Seconds 4379226 & 4379228 200 Seconds (1) After hot restart.
3. If plunger does not operate, turn ignition off. Connect a voltmeter to the idle solenoid (Blue wire) at the carburetor connector and ground. Start the engine. Voltage reading should be within one volt of battery voltage for the length of time specified in the «ELECTRONIC THROTTLE CONTROL»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting) table. If voltage reading is not okay, go to step 6). If voltage reading is okay, go to next step. (Scheme 322): Testing Idle Control System Voltage
4. After specified length of time, voltage reading should drop to zero volt. If voltage reading is okay, turn ignition off. Disconnect the computer 12-pin connector. Back off adjusting screw on idle solenoid 3 turns. Set throttle on highest step of the fast idle cam.
5. Connect a jumper wire to the solenoid (Blue wire) at the carburetor connector. Touch other end of jumper lead to battery positive terminal while observing solenoid plunger. Plunger should extend when voltage is applied. If plunger extends, set idle speed to specifications. If solenoid does not extend, replace the solenoid. (Scheme 323): Jumper Wire Attachment Location
6. If voltage reading in step 3) is not okay, disconnect the computer 12-pin connector. Connect an ohmmeter between the connector cavity No. 5 and the idle solenoid (Blue wire) at the carburetor connector. Ohmmeter should show continuity. If there is no continuity, repair wiring to connector cavity No. 5 for an open circuit to the carburetor connector. (Scheme 324): Connecting Ohmmeter Between 12-Pin Connector & Blue Wire at Carburetor Connector
7. If there is continuity, check the terminal in connector cavity No. 5 to ensure it is not spread apart causing a poor connection. If terminal is okay, replace the computer. If solenoid plunger in step 2) extends, but does not retract after specified length of time, replace the computer. NOTE: On models equipped with A/C or rear window defroster, ensure they are turned off before diagnosing the computer as defective.
8. If plunger movement in step 2) is okay, on models without A/C or rear window defroster, connect a tachometer. Connect a jumper lead between idle solenoid (Blue wire) at the carburetor connector and the positive battery terminal. Open throttle slightly and release. Tachometer reading should be within 100 RPM of specifications. see scheme 64: Jumper Wire Attachment Location
9. If solenoid idle speed is okay, proceed to «WARM DR-11»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__warm-dr-11-ignition-timing-system). If solenoid idle speed is not to specifications, set idle to specifications using the following procedure. Disconnect and plug vacuum hose to the EGR valve. Ground the carburetor switch using a jumper lead. Disconnect and plug 3/16" vacuum hose at the vapor canister.
10. Remove the PCV valve from the valve cover and allow it to draw outside air. Connect a tachometer. Start the engine and let the idle speed stabilize for 2 minutes. Energize the solenoid. Open throttle slightly to allow solenoid plunger to extend. Remove the solenoid adjusting screw and spring.
11. Insert a 1/8" Allen wrench into the solenoid and rotate to adjust solenoid to specifications. Reinstall solenoid adjusting screw and spring until it lightly bottoms out. De-energize the solenoid. Disconnect the engine harness connector from the O 2 sensor and ground the engine harness lead using a jumper wire.
12. Allow the engine to run for 4 minutes to stabilize O 2 sensor circuit. Rotate the solenoid adjusting screw to adjust the speed to specification listed on emission label. Reconnect the O 2 sensor wire. Reinstall PCV valve and install hoses that were disconnected. Remove ground wire from carburetor switch. NOTE: Engine RPM in normal operating condition (everything connected) may vary from set speeds. DO NOT readjust.
13. If plunger movement in step 2) is okay, on models with A/C or rear window defroster, connect a tachometer. Disconnect the A/C compressor clutch wiring. Have an assistant press the A/C button or the rear window defroster switch while you observe the solenoid plunger and tachometer. It may be necessary to open and close the throttle to activate the solenoid.
14. Solenoid plunger should extend and increase idle speed to specification. If plunger movement and solenoid idle speed is okay, proceed to «WARM DR-11»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__warm-dr-11-ignition-timing-system). Adjust solenoid idle speed as necessary. If plunger does not extend, turn ignition off. Disconnect the 10-pin connector from the computer. Connect a voltmeter to connector cavity No. 4 and ground. (Scheme 325): Measuring Voltage at 10-Pin Connector Pin 4
15. Turn the ignition switch to the "RUN" position. Press the A/C button or the rear window defroster switch. Voltmeter reading should be within one volt of battery voltage. If voltage reading is okay, check the terminal in connector cavity No. 4 to ensure it is not spread apart causing a poor connection. If terminal is okay, replace the computer.
16. If voltage reading is not okay, repair wiring to connector cavity No. 4 for an open circuit. There are 2 diodes in the circuit which could be the cause of the open circuit. See wiring diagram at end of this article.
17. If plunger movement in step 2) is okay, on models with A/C and rear window defroster, press the A/C button. Observe the rear window defroster indicator light. Light should be off. If light is on, replace rear window defroster isolation diode.
18. If light is off, turn the A/C off. Turn the rear window defroster on. Listen for A/C compressor clutch engagement. A/C compressor clutch should not engage. If compressor clutch engages, replace the A/C isolation diode.
19. If clutch does not engage, turn rear window defroster off. Connect a tachometer. Disconnect A/C compressor clutch wiring. Have an assistant press the A/C button while you observe the solenoid plunger and the tachometer.
20. Open and close throttle to activate solenoid if necessary. Solenoid plunger should extend and increase solenoid idle speed to specifications. If plunger movement and idle speed are okay, turn A/C off and turn rear window defroster on.
21. Repeat steps 19) and 20). If plunger movement and idle speed are okay, proceed to «WARM DR-11»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__warm-dr-11-ignition-timing-system). Adjust solenoid idle speed as necessary. If there is no plunger movement when A/C is turned on, replace A/C isolation diode.
22. If there is no plunger movement when the rear window defroster is turned on, replace the rear window defroster isolation diode. If there is no plunger movement when either A/C or rear window defroster is turned on, turn the ignition off. Disconnect the computer 10-pin connector. Connect a voltmeter to connector cavity No. 4 and ground.
23. Turn the ignition switch to the "RUN" position. Turn the A/C or rear window defroster on. Voltage reading should be within one volt of battery voltage. If voltage reading is okay, check the terminal in connector cavity No. 4 to ensure it is not spread apart causing a poor connection. If terminal is okay, replace the computer.
24. If voltage reading is not okay, repair wiring to 10-pin connector cavity No. 4 for an open circuit. There is a diode in the A/C circuit which could be the cause of the open circuit.

WARM DR-11 - IGNITION TIMING SYSTEM CHECK

1. Connect a tachometer and timing light. Ground the carburetor switch. Start the engine. Raise engine speed to more than 1100 RPM until engine reaches normal operating temperature. On 2-Bbl. models, disconnect and plug the vacuum hose to the computer.
2. Engine speed should be 450-650 RPM on 2-Bbl. models and 550-750 RPM on 4-Bbl. models. Adjust idle speed as necessary. Basic timing should be within 2 degrees of specifications. See the «BASIC TIMING SPECIFICATIONS»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting) table below. Adjust timing as necessary. BASIC TIMING SPECIFICATIONS Computer No. Specification 4379484 & 4379682 7°BTDC 4379226 & 4379228 16°BTDC
3. If basic timing is okay, remove jumper lead from carburetor ground switch. On 4-Bbl. models, disconnect and plug vacuum hose to the computer. Connect a vacuum pump to the computer and apply 16 in. Hg vacuum. Raise engine speed to more than 2000 RPM. Timing should be within 4 degrees of specifications. See the «SPARK ADVANCE SPECIFICATIONS»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting) table below. SPARK ADVANCE SPECIFICATIONS (1) Application Computer No. Advance Spark 5.2L (2-Bbl.) 4379484 46°BTDC 5.2L (2-Bbl.) 4379682 46°BTDC 5.2L (4-Bbl.) 4379226 38°BTDC 5.2L (4-Bbl.) 4379228 38°BTDC (1) Specifications are +/- 4 degrees.
4. If spark advance is not within specifications, replace the computer. If spark advance is okay, apply 16 in. Hg vacuum (2-Bbl. models) and 2 in. Hg vacuum (4-Bbl. models) to the computer. Position fast idle speed screw on the 2nd highest step of the fast idle cam. Tap lightly on the intake manifold near the detonation sensor while watching the timing. Timing should retard as you tap on the intake manifold. NOTE: The amount of timing retard is directly proportional to the frequency of the tapping. Maximum retard is 16 degrees.
5. If timing does not retard, check the wiring between the detonation sensor and the computer for open or short circuits. If wiring is okay, replace the detonation sensor and repeat step 4). If timing still does not retard, replace the computer.
6. If timing retards, return engine to idle speed. Unplug vacuum supply hose to the computer and connect a vacuum gauge to it. Vacuum reading should be manifold vacuum. If vacuum reading is not as specified, check and repair vacuum supply from carburetor. If vacuum reading is okay, proceed to WARM DR-12 below.

WARM DR-12 - IDLE RPM CHECK

1. Set parking brake. Place transmission in Neutral. Turn all lights and accessories off. Connect a tachometer. Ground carburetor switch using a jumper lead. Disconnect and plug vacuum hose to the EGR valve. Remove PCV valve from valve cover and allow it to draw outside air.
2. Disconnect and plug 3/16" hose from vapor canister. On 2 Bbl. models, disconnect and plug vacuum hose to the computer. Disconnect the carburetor 4-pin connector and remove the O 2 solenoid (Green wire) from the carburetor connector. Reconnect carburetor connector. Start the engine and let stabilize for 4 minutes.
3. On 4-Bbl. models, connect a voltmeter to O 2 solenoid (Green wire) and ground. Disconnect O 2 sensor wiring and ground O 2 sensor harness connector using a jumper lead. Start the engine and let run until voltmeter reading is a steady 7-13 volts. This may take up to 4 minutes. Tachometer reading should be at specification shown on emission label.
4. Adjust idle RPM as necessary. Tee in propane supply into heated air temperature vacuum supply hose. Slowly meter propane supply into hose until maximum RPM is obtained. Engine speed should increase 10-110 RPM (2-Bbl. models) and 0-100 RPM (4-Bbl. models). Adjust propane idle speed as necessary. Proceed to WARM DR-13 below.

WARM DR-13 - HEATED AIR INTAKE SYSTEM CHECK

1. Remove outside air duct from the air cleaner. Start the engine. The heated air door should be laying flat in snorkel. If heated air door is not in proper position, disconnect vacuum supply hose from temperature sensor. Connect a vacuum pump to the sensor and apply 10 in. Hg vacuum.
2. Vacuum should bleed down. If vacuum bleeds down, check for sticking heated air door or a faulty vacuum delay valve (if equipped). If vacuum does not bleed down, replace temperature sensor. If heated air door is in proper position in step 1), on 2-Bbl. models, proceed to «WARM DR-14»(/chrysler/fifth-avenue/ii-1990-1993/remont/testing-diagnostics/#52l-efc-systemtesting__warm-dr-14-verification-test) .
3. On 4-Bbl. models, watch vapor containment door. Vapor containment door should be open. If vapor containment door is not open, check for sticking door or faulty vacuum delay valve. If door is open, proceed to WARM DR-14 below.

WARM DR-14 - VERIFICATION TEST

At this point, test procedures have determined that all engine control systems are operating correctly and are not the cause of the driveability problem. Check the following as possible causes

1. Check for at least 13 in. Hg engine vacuum in Neutral.
2. Check engine valve timing.
3. Check engine compression.
4. Check engine cooling system.
5. Check exhaust system for restrictions.
6. Check engine PCV system for free flow.
7. Check intake manifold heat crossover for plugging.
8. Check torque converter stall speed.
9. Check power brake booster for internal vacuum leaks.
10. Check for fuel contamination.
11. Check carburetor for circuit contamination and proper calibration.
12. Check Technical Service Bulletins that may apply to vehicle.

RWD Electronic Fuel Control (EFC) System Wiring Diagram. Scheme 326

See also:
• NS-1
• NS-2
• NS-3
• NS-4
• NS-5
• NS-6
• NS-7A
• COLD DR-1
• COLD DR-2A
• COLD DR-2B
• COLD DR-3
• COLD DR-7
• COLD DR-8
• COLD DR-12
• COLD DR-13
• WARM DR-1
• WARM DR-4
• WARM DR-6
• WARM DR-11
• WARM DR-12
• WARM DR-13