Engine Controls - Basic Testing - 5.2L: Diagnosis

Engine Controls - Basic Testing - 5.2L: 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.

«VACUUM DIAGRAMS»(ref-10901) (For Dakota)
«VACUUM DIAGRAMS»(ref-10928) (For Pickup)
«VACUUM DIAGRAMS»(ref-10929) (For Ram Van/Ram Pickup)

MECHANICAL INSPECTION

CAUTION

Use a remote starter to crank engine during compression test; DO NOT use ignition switch. Fuel injectors on many models are triggered by ignition switch during engine cranking. This could create a fire hazard or cause engine flooding, crankcase contamination, hydrostatic lock or lubrication to be washed from cylinder walls.

Fuel Pump Pressure Test

Begin basic diagnosis of fuel system by determining fuel system pressure. Release fuel pressure. See FUEL PRESSURE RELEASE.
Remove fuel rail test port protective cap. Connect Fuel Pressure Gauge (C-4799) to fuel rail test port. Test port is located at rear of engine. Start engine and allow to idle. If pressure is more than 45 psi (310 kPa), fuel pump is okay. Replace fuel filter/fuel pressure regulator assembly located on top of fuel pump module. If pressure is zero psi, use DRB diagnostics. Proceed to article in the ENGINE PERFORMANCE section.

Application	Pressure - psi (kPa)
5.2L	35-45 (241-310)
(1) Fuel pressure taken at engine idle (no load).

(1)	Fuel pressure taken at engine idle (no load).

FUEL PUMP REGULATED PRESSURE (1)

TESTING SPARK AT COIL

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.
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.
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 - 5.2L»(ref-10877) article in the ENGINE PERFORMANCE section.

IGNITION COIL RESISTANCE TEST

Inspect coil for arcing. Measure coil primary and secondary resistance. See IGNITION COIL RESISTANCE table. Replace coil if resistance is not within specification.

Application	Primary	Secondary
Diamond	0.97-1.18	11,300-15,300
Toyodenso	0.95-1.20	11,300-13,300

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.

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.
If voltage remains near zero during entire period of cranking, see «TESTS W/CODES - 5.2L»(ref-10877) 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 - 5.2L»(ref-10877) article in the ENGINE PERFORMANCE section to check PCM circuit.
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.
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 84)and (Scheme 85). Spark should be generated when ground connection is disconnected.
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.