Engine Controls - Basic Testing - 2.5L: Diagnosis Dodge Dakota WS

VISUAL INSPECTION

Perform a visual inspection of all electrical wirings. Look for chafed, stretched, cut or pinched wiring. Inspect electrical connectors and connections for tight fit and corrosion. Repair as necessary. Inspect all vacuum hoses for proper routing, cuts or pinches. If necessary, see appropriate VACUUM DIAGRAMS article in the ENGINE PERFORMANCE section below to verify routing and connections. Repair as necessary. Inspect air induction system for possible vacuum leaks.

1. «VACUUM DIAGRAMS»(ref-10900) (For Caravan)
2. «VACUUM DIAGRAMS»(ref-10901) (For Dakota)
3. «VACUUM DIAGRAMS»(ref-10902) (For Voyager)

MECHANICAL INSPECTION

Fuel Pump Pressure Test

1. Begin basic diagnosis of fuel system by determining fuel system pressure. Release fuel pressure. See FUEL PRESSURE RELEASE.
2. On 2.5L engines, disconnect fuel supply hose. Connect Fuel Pressure Test Adapter (6539) between fuel supply hose and engine fuel line. Connect Fuel Pressure Gauge (C-4799) to Fuel Pressure Test Adapter (6539).
3. Turn ignition on. Using Diagnostic Readout Box (DRB), access ASD Fuel System Test. ASD Fuel System Test will activate fuel pump and pressurize fuel system. If fuel pump pressure is at specification, fuel system is functioning properly. See «FUEL PUMP REGULATED PRESSURE»(ref-10899-S20497465762000111000000) table.
4. If fuel pressure is more than specification, go to step 7). If fuel pressure is less than specification, record pressure. Repeat FUEL PRESSURE RELEASE procedure. Install fuel pressure gauge in fuel supply line at rear of vehicle between fuel tank and fuel filter.
5. Turn ignition on and using DRB, activate fuel pump. Record pressure reading. If fuel pressure is 5 psi (34.5 kPa) more than first pressure reading, replace fuel filter.
6. If no change in pressure reading is observed, gently squeeze fuel return hose. If fuel pressure increases, replace fuel pressure regulator. If no change in fuel pressure is observed, problem is plugged fuel pump inlet strainer or a defective fuel pump.
7. If fuel pressure is more than specification, repeat fuel pressure release procedure. See FUEL PRESSURE RELEASE. Ensure fuel tank is at least half full. Install fuel gauge in fuel supply hose between fuel and fuel filter. Remove fuel return hose at fuel tank and connect an extension hose to return hose. Place hose in an approved container with at least a 2 gallon capacity.
8. Turn ignition on. Using DRB, activate fuel pump. If fuel pressure is now within specification, check in-tank return fuel hose for kinking. Replace fuel pump assembly if in-tank reservoir check valve or aspirator jet is plugged.
9. If fuel pressure is still more than specification, repeat FUEL PRESSURE RELEASE procedure. Disconnect fuel return hose from chassis fuel line (at engine). Connect fuel pressure gauge to fuel return hose and place other end of hose in an approved container with at least a 2 gallon capacity. Using DRB, repeat fuel pressure test. If fuel pressure is correct, check for restricted fuel return line. If there is no change, replace fuel pressure regulator.

FUEL PUMP REGULATED PRESSURE (1)

TESTING SPARK AT COIL

1. Remove coil wire from distributor cap. Hold end of cable approximately 1/2" (13 mm) from engine ground. Crank engine and check for spark from coil wire. Spark should be present and constant.
2. If spark is present and constant, continue cranking engine. Slowly move coil wire away from ground. As coil wire is moved away from ground, check for arching at coil tower. If arching at coil tower is present, replace coil.
3. If spark is good and no arching is present, secondary ignition system is producing necessary voltage. Ensure spark reaches spark plugs by checking condition of rotor, cap, spark plug wires and spark plugs. Repair or replace secondary ignition components as necessary. If ignition system components are in good condition, ignition system is okay. If vehicle still fails to start, proceed to NO-START TEST. Also refer to «TESTS W/CODES - 2.5L TBI»(ref-10881) article in the ENGINE PERFORMANCE section.

IGNITION COIL RESISTANCE TEST

1. Inspect coil for arcing. Measure coil primary and secondary resistance. See IGNITION COIL RESISTANCE table. Replace coil if resistance is not within specification.
2. Remove spark plug wires from coil one at a time. Measure secondary resistance of ignition coil between grouped cylinders and coil towers. Replace coil if resistance is not within specification. See IGNITION COIL RESISTANCE table. If ignition system components are in good condition, ignition system is okay. If vehicle still fails to start, proceed to NO-START TEST.

IGNITION COIL RESISTANCE - Ohms @ 70-80°F (21-27°C)

NO-START TEST

Note. Perform TESTING SPARK AT COIL before proceeding with NO-START TEST.

1. Unplug coil connector and coil. Connect a pair of jumper wires between coil and coil connector. Ensure sufficient battery voltage (12.4 volts) is available to crank engine and operate ignition systems. Crank engine for 5 seconds while monitoring voltage at coil positive terminal.
2. If voltage remains near zero during entire period of cranking, see «TESTS W/CODES - 2.5L TBI»(ref-10881) article in the ENGINE PERFORMANCE section to check PCM and ASD relay. If voltage is near battery voltage and drops to zero after 1-2 seconds of cranking, see «TESTS W/CODES - 2.5L TBI»(ref-10881) article in the ENGINE PERFORMANCE section to check PCM circuit.
3. If voltage remains near battery voltage during entire 5 seconds, turn ignition switch to OFF position. Disconnect PCM 60-pin connector. Check 60-pin connector for loose terminals (push-outs). If connector is okay, go to next step.
4. Remove positive lead from coil. Connect a jumper wire between positive battery terminal and coil positive terminal. Using a specially constructed jumper wire, momentarily ground PCM harness connector terminal No. 19. (Scheme 79)and (Scheme 80). Spark should be generated when ground connection is disconnected.
5. If spark is generated, replace PCM. If no spark is generated, use special jumper wire directly on coil negative terminal. If spark is produced, repair wiring harness for an open circuit. If no spark is produced, replace ignition coil.

Scheme 79

Scheme 80

See also:
• COMPUTER RELEARN PROCEDURES