Engine Controls - Basic Testing - 3.5l Chrysler New Yorker XIV

INTRODUCTION

The following diagnostic steps help prevent overlooking a simple problem. This is also where to begin diagnosis for a no-start condition.

The first step in diagnosing any driveability problem is verifying the customer's complaint with a test drive under the conditions the problem reportedly occurred.

Before entering self-diagnostics, perform a careful and complete visual inspection. Most engine control problems result from mechanical breakdowns, poor electrical connections or damaged/misrouted vacuum hoses. Before condemning the computerized system, perform each test listed in this article.

Note. Perform voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless otherwise stated in test procedure.

VISUAL INSPECTION

Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wires. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and are not pinched or cut. See VACUUM DIAGRAMS article to verify routing and connections (if necessary). Inspect air induction system for possible vacuum leaks.

Compression

Check engine mechanical condition with a compression gauge, vacuum gauge or engine analyzer. See engine analyzer manual for specific instructions.

ENGINE COMPRESSION SPECIFICATIONS

Exhaust System Backpressure

The exhaust system can be checked with a vacuum gauge or pressure gauge. If using a pressure gauge, remove oxygen sensor or air injection check valve (if equipped). Connect a 0-10 psi gauge, and operate engine at 2500 RPM. If exhaust system backpressure is greater than 1 3/4 - 2 psi, exhaust system or catalytic converter is plugged.

If a vacuum gauge is used, connect it to intake manifold vacuum, and start engine. Observe vacuum gauge. Open throttle part way and hold it steady. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for restriction.

* PLEASE READ THIS FIRST *

FUEL PRESSURE

Basic diagnosis of fuel system should begin with determining fuel system pressure.

Relieving Fuel Pressure (Vehicles With Fuel Rail Test Port) -Disconnect negative battery cable. Slowly open fuel tank cap to release pressure in tank. To release remaining pressure in system, remove fuel rail pressure test port cap. Place open end of Fuel Pressure Release Hose (C-4799-A) in approved gasoline container. Connect other end of pressure release hose to test port. Fuel pressure will bleed-off into container.

Relieving Fuel Pressure (Vehicles Without Fuel Rail Test Port) -Disconnect fuel pump wiring harness connector at fuel tank. Start engine. Let engine run until fuel is exhausted and engine stops. Turn ignition off. Disconnect negative battery cable. Connect fuel pump wiring harness connector.

Checking Fuel Pressure (Vehicles With Fuel Rail Test Port)

1. Relieve fuel pressure. On vehicles with vacuum assisted fuel pressure regulators, disconnect vacuum hose from fuel pressure regulator before checking fuel pressure. Remove fuel rail test port protective cap. Connect Fuel Pressure Gauge (C-4799) to fuel rail test port. CAUTION: DO NOT activate fuel pump for long periods, or engine may hydrostatically (liquid) lock.
2. Turn ignition switch to ON position. Using Diagnostic Readout Box (DRB), select ASD FUEL SYSTEM TEST mode. In this mode, DRB energizes Auto Shutdown (ASD) relay, causing fuel pump to activate and pressurize fuel system.
3. Note fuel pressure, and record reading. Deactivate fuel pump. Relieve fuel pressure. Remove fuel pressure gauge. Reactivate fuel pump. Ensure fuel does not leak from fuel rail test port. Deactivate fuel pump. Install fuel rail test port protective cap.
4. If fuel pressure is within specification, fuel system is functioning properly and further testing is not required. See «FUEL SYSTEM PRESSURE SPECIFICATIONS»(/chrysler/new-yorker/xiv-1994-1996/remont/testing-diagnostics/#engine-controls-basic-testing-35l) table. If fuel pressure is greater than specification, go to step 7). If fuel pressure is less than specification, install Fuel Pressure Gauge (C-4799) and appropriate fuel pressure test adapter in fuel supply line between fuel tank and fuel filter.
5. Using DRB, repeat ASD FUEL SYSTEM TEST. If fuel pressure is at least 5 psi greater than fuel pressure recorded in step 3), replace fuel filter. If no change in fuel pressure is observed, gently squeeze fuel return hose.
6. If fuel pressure increases while squeezing fuel return hose, replace fuel pressure regulator. If fuel pressure does not change while squeezing fuel return hose, check for plugged fuel inlet strainer or defective fuel pump. Repair as necessary.
7. Remove fuel return hose from fuel pump at fuel tank. Connect fuel pressure test adapter to return hose. Place other end of adapter into an approved gasoline container (minimum 2 gallon size).
8. Turn ignition switch to ON position. Repeat ASD FUEL SYSTEM TEST. If fuel pressure is now correct, replace fuel pump assembly. See FUEL SYSTEM PRESSURE SPECIFICATIONS table. If pressure is still greater than specification, deactivate fuel pump. Remove fuel pressure test adapter, and connect fuel pump return hose.
9. Disconnect fuel return hose from chassis fuel lines at engine. Connect fuel pressure test connector adapter to fuel return hose. Place other end of hose in approved gasoline container. Repeat ASD FUEL SYSTEM TEST.
10. If fuel pressure is now correct, check for restricted fuel return line. If no change is observed, replace fuel pressure regulator.

FUEL SYSTEM PRESSURE SPECIFICATIONS

Checking Fuel Pressure (Vehicles Without Fuel Rail Test Port)

1. Relieve fuel pressure. On vehicles with vacuum assisted fuel pressure regulators, disconnect vacuum hose from fuel pressure regulator before checking fuel pressure.
2. On all vehicles, disconnect fuel supply hose from chassis lines at engine. Connect Fuel Pressure Gauge (C-4799) to appropriate fuel pressure test adapter. Install adapter between fuel supply hose and chassis fuel line. CAUTION: DO NOT activate fuel pump for long periods, or engine may hydrostatically (liquid) lock.
3. Turn ignition switch to ON position. Using Diagnostic Readout Box (DRB), select ASD FUEL SYSTEM TEST mode. In this mode, DRB energizes Auto Shutdown (ASD) relay, causing fuel pump to activate and pressurize fuel system.
4. Note fuel pressure, and record reading. Stop ASD FUEL SYSTEM test mode. Relieve fuel pressure. Remove fuel pressure gauge. If fuel pressure is within specification, fuel system is functioning properly and further testing is not required. See «FUEL SYSTEM PRESSURE SPECIFICATIONS»(/chrysler/new-yorker/xiv-1994-1996/remont/testing-diagnostics/#engine-controls-basic-testing-35l) table.
5. If fuel pressure is greater than specification, go to step 8). If fuel pressure is less than specification, install Fuel Pressure Gauge(C-4799) and fuel pressure test adapter in fuel supply line between fuel tank and fuel filter.
6. Repeat ASD FUEL SYSTEM TEST. If fuel pressure is at least 5 psi greater than fuel pressure recorded in step 4), replace fuel filter. If no change is observed, gently squeeze fuel return hose.
7. If fuel pressure increases while squeezing fuel return hose, replace fuel pressure regulator. If fuel pressure does not change while squeezing fuel return hose, problem may either be a plugged fuel inlet strainer or defective fuel pump. Repair as necessary.
8. Disconnect fuel return hose from fuel pump at fuel tank. Connect appropriate fuel pressure test adapter to fuel return hose. Place other end of adapter into an approved 2 gallon gasoline container.
9. Turn ignition switch to ON position. Repeat ASD FUEL SYSTEM TEST. If pressure is now correct, replace fuel pump assembly. See «FUEL SYSTEM PRESSURE SPECIFICATIONS»(/chrysler/new-yorker/xiv-1994-1996/remont/testing-diagnostics/#engine-controls-basic-testing-35l) table. If pressure is still greater than specification, deactivate fuel pump. Remove fuel pressure test adapter, and connect fuel pump return hose.
10. Disconnect fuel return hose from chassis fuel lines at engine. Connect fuel pressure test connector adapter to fuel return hose. Place other end of hose in an approved gasoline container. Repeat ASD FUEL SYSTEM TEST.
11. If pressure is now correct, check for restricted fuel return line. If no change is observed, replace fuel pressure regulator.

IGNITION SYSTEM IDENTIFICATION

IGNITION SYSTEM IDENTIFICATION

Spark Test

1. Remove spark plug cable from cylinder No. 2. Insert a known-good spark plug into spark plug cable. Ground spark plug on engine. Crank engine and check for spark. Repeat procedure at remaining cylinders.
2. If no spark or an irregular, weak spark is present at one or more spark plug cables, go to IGNITION CABLE RESISTANCE TEST. If no spark is present, go to NO-START TEST.

Ignition Cable Resistance Test

Remove ignition cables, and measure their resistance (3000-12,000 ohms per foot). Replace cable(s) if cable resistance is not as specified. If resistance is as specified, go to IGNITION COIL RESISTANCE TEST.

Ignition Coil Resistance Test

1. Disconnect ignition coil harness connector. Measure primary coil resistance between battery voltage terminal and pin corresponding to cylinder(s) in question. (Scheme 14)
2. Measure secondary coil resistance between coil towers of grouped cylinders; No. 1 and 4, 2 and 5, and 3 and 6. Replace ignition coil if primary/secondary coil resistance is not as specified. See IGNITION COIL RESISTANCE table under IGNITION COIL.

No-Start Test

1. Ensure battery is fully charged (at least 12.6 volts). Disconnect coil electrical connector. Connect a test light to coil electrical connector battery voltage terminal. (Scheme 14)
2. Turn ignition switch to ON position. Test light should momentarily flash on and off. If test light does not momentarily flash on and off, ASD relay has failed to energize. Check ASD relay and related circuits. See appropriate «TESTS W/CODES - 3.5L»(/chrysler/new-yorker/xiv-1994-1996/remont/testing-diagnostics/#engine-controls-tests-wcodes-35l) article.
3. If test light momentarily flashes on and off, PCM has grounded Auto Shutdown (ASD) relay. Go to next step. DO NOT turn ignition off at this time.
4. Crank engine, and observe test light. If ignition was turned off at end of step 3), turn ignition switch to ON position, wait for test light to flash once, and then crank engine.
5. If test light momentarily flashes during cranking, engine controller is not receiving a camshaft sensor signal. Check camshaft sensor and related sensor circuits. See «TESTS W/CODES - 3.5L»(/chrysler/new-yorker/xiv-1994-1996/remont/testing-diagnostics/#engine-controls-tests-wcodes-35l) article.
6. If test light does not flash during cranking, disconnect camshaft sensor connector. Turn ignition switch to OFF and then to ON position. Wait for test light to momentarily flash once, and then crank engine.
7. If test light momentarily flashes, camshaft sensor is shorted and must be replaced. If test light does not flash, no-start condition is caused by problem in crankshaft or camshaft sensor 9-volt power supply circuit or by crankshaft sensor 5-volt output or ground circuits. See appropriate «TESTS W/CODES - 3.5L»(/chrysler/new-yorker/xiv-1994-1996/remont/testing-diagnostics/#engine-controls-tests-wcodes-35l) article.

Scheme 14

See SPARK TEST under OPTICAL IGNITION SYSTEM .

Ignition Coil Resistance

Ignition coil resistance test procedure is not available from manufacturer. Use IGNITION COIL RESISTANCE table under IGNITION COIL to determine correct coil resistance.

Scheme 15

1. Remove ignition coil secondary cable from distributor cap. Hold end of cable 1/4" away from a known-good engine ground. Crank engine and check for spark.
2. If spark is not constant or if there is no spark, go to step 4). If spark is constant, slowly move coil secondary cable away from ground while assistant cranks engine. If arcing occurs at coil tower, replace ignition coil.
3. If spark is constant and no arcing occurs, ignition system secondary voltage is correct. Ensure secondary voltage reaches spark plugs, indicating ignition system is okay. Go to «MECHANICAL INSPECTION»(/chrysler/new-yorker/xiv-1994-1996/remont/testing-diagnostics/#engine-controls-basic-testing-35l) under PRELIMINARY INSPECTION & ADJUSTMENTS. Perform tests under «FUEL SYSTEM»(/chrysler/new-yorker/xiv-1994-1996/remont/testing-diagnostics/#engine-controls-basic-testing-35l).
4. Ensure battery is fully charged (at least 12.4 volts). Connect volt-meter to ignition coil B+ (battery voltage) terminal. Crank engine for at least 5 seconds while checking voltage at coil terminal.
5. If voltage remains near zero during entire cranking period, test Auto Shutdown (ASD) relay circuit. See appropriate «TESTS W/CODES - 3.5L»(/chrysler/new-yorker/xiv-1994-1996/remont/testing-diagnostics/#engine-controls-tests-wcodes-35l) article.
6. If voltmeter reading is near battery voltage and then drops to zero after 1-2 seconds of cranking, test distributor reference pick-up circuit. See appropriate «TESTS W/CODES - 3.5L»(/chrysler/new-yorker/xiv-1994-1996/remont/testing-diagnostics/#engine-controls-tests-wcodes-35l) article.
7. If voltmeter reading remains at or near battery voltage during entire cranking period, turn ignition off. Disconnect 60-pin connector from Powertrain Control Module (PCM), and check terminals for poor connections. (Scheme 15)
8. Remove positive lead from coil. Connect a jumper wire between battery positive terminal and coil positive terminal. Using a specially constructed jumper wire, momentarily ground PCM harness connector terminal No. 19. (Scheme 16) Spark should occur when ground connection is disconnected.
9. If spark occurs, replace PCM. If spark does not occur, ground coil negative terminal using specially constructed jumper wire. If spark occurs, repair open circuit in wiring harness. If spark does not occur, replace ignition coil.

Ignition coil resistance test procedure is not available from manufacturer. Use IGNITION COIL RESISTANCE table under IGNITION COIL to determine correct coil resistance.

Scheme 16

IGNITION COIL

IGNITION COIL RESISTANCE - Ohms @ 68°F (20°C) (1)

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see ADJUSTMENTS - 3.5L article.

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES proceed to appropriate TESTS W/CODES - 3.5L article. If no hard codes are found in self-diagnostics, proceed to appropriate TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.) or intermittent diagnostic procedures.

See also:
• COMPUTER RELEARN PROCEDURES
• TESTS W/CODES - 3.5L
• TESTS W/O CODES
• FUEL SYSTEM PRESSURE SPECIFICATIONS