Engine Controls - Basic Testing - Gasoline: Other Dodge Cab & Chassis Dakota

COMPRESSION

Check engine mechanical condition using a compression gauge, vacuum gauge, or an engine analyzer capable of performing a relative compression test. See engine analyzer instruction manual for availability and description of relative compression feature.

ENGINE COMPRESSION

EXHAUST SYSTEM BACKPRESSURE

Check exhaust system with a vacuum gauge or pressure gauge. Remove O2 sensor or air injection check valve (if equipped). Connect a 1-5 psi pressure gauge, and run engine at 2500 RPM. If exhaust system backpressure is greater than 1 3/4-2 psi, exhaust system or catalytic converter is plugged.

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

FUEL PRESSURE

Begin basic diagnosis of fuel system by determining fuel system pressure.

ALWAYS relieve fuel pressure before attempting to open system for testing or component replacement. High fuel pressure may be present in fuel lines and component parts. DO NOT allow fuel to flow onto engine or electrical parts while testing fuel system components.

FUEL PRESSURE RELEASE

1. Fuel pressure must be fully released before opening fuel system or removing any fuel-carrying components. To release pressure in tank, open fuel tank cap slowly.
2. To release remaining pressure in system, disconnect injector wiring harness. Using jumper wire, connect injector harness ground terminal No. 1 to ground. (Scheme 1), (Scheme 2), or (Scheme 3). Connect injector harness positive terminal No. 2 to positive battery terminal with second jumper wire.
3. DO NOT keep injector connector connected to positive battery terminal for longer than 5 seconds. Remove jumper wires. Fuel injection system can now be opened and fuel-carrying components removed as pressure is fully released.

Scheme 1

Scheme 2

Scheme 3

Note. Perform FUEL PUMP TEST with fuel tank at least half full. Before disconnecting a fuel line during testing, repeat FUEL PRESSURE RELEASE procedure.

AUTO SHUTDOWN (ASD) RELAY

Note. If ASD relay is suspected of causing a fuel or ignition system malfunction, it will be necessary to use Diagnostic Readout Box (DRB-II) to diagnose ASD relay. See appropriate SELF-DIAGNOSTICS article.

2.5L, 3.0L, 3.9L, 5.2L & 5.9L

When distributor signal is not present with ignition switch in RUN position, ASD relay turns off power to electric fuel pump, fuel injectors, ignition coil and O2 sensor heating element.

3.3L

When there is no camshaft or crankshaft sensor signal with ignition switch in RUN position, ASD relay turns off power to electric fuel pump, fuel injectors, ignition coil and O2 sensor heating element.

1. Remove coil wire from distributor cap. Hold end of cable approximately 1/4" from 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 as necessary. If ignition system components are in good condition, ignition system is okay.

1. This system has 3 independent coils. These coils must be tested separately. Remove spark plug wire from No. 2 spark plug. Insert a clean screwdriver into spark plug boot.
2. Hold screwdriver approximately 1/4" from ground. Crank engine and watch for spark between screwdriver and ground. Repeat this test for No. 4 and No. 6 spark plug wires.
3. If no spark is present on any cylinder tested, go to NO-START TEST. If one or more cylinders has weak or no spark, go to next step.
4. Remove spark plug wires individually. Using an ohmmeter, measure resistance of each spark plug wire. Resistance should be 3000-12,000 ohms per foot. Replace spark plug wire(s) if resistance is not within specification.
5. Measure resistance on primary side of each coil. Resistance should be.5-.7 ohm. Measure resistance between B+ terminal of ignition coil connector and corresponding cylinders. (Scheme 4) Replace coil if resistance is not within specification.
6. Remove spark plug wires from coil one at a time. Measure secondary resistance of ignition coil between grouped cylinders and coil towers. Resistance should be 7000-15,800 ohms. Replace coil if resistance is not within specification.

Scheme 4

Note. Perform TESTING SPARK AT COIL before proceeding with test.

1. 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 appropriate SELF-DIAGNOSTICS article to check SBEC and ASD relay. If voltage is near battery voltage and drops to zero after 1-2 seconds of cranking, see appropriate SELF-DIAGNOSTICS article to check distributor pick-up circuit to SBEC.
3. If voltage remains near battery voltage during entire 5 seconds, turn ignition off. Disconnect SBEC 60-pin connector. Check 60-pin connector for loose terminals (push-outs).
4. 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 SBEC harness connector terminal No. 19. (Scheme 5)and (Scheme 6). Spark should be generated when ground connection is disconnected.
5. If spark is generated, replace SBEC. 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 5

Scheme 6

Note. Perform TESTING SPARK AT COIL before proceeding with test.

1. Ensure sufficient battery voltage (12.4 volts) is available to operate cranking and ignition systems. Connect voltmeter between B+ wiring harness coil connector and ground. (Scheme 7)
2. Crank engine for 5 seconds while monitoring voltage at B+ terminal. If voltage remains near zero during entire period of cranking, see appropriate SELF-DIAGNOSTICS article to check SBEC and ASD relay.
3. If voltage is near battery voltage and drops to zero after 1-2 seconds of cranking, see appropriate SELF-DIAGNOSTICS article to check cam and crank sensor circuits to SBEC.
4. If voltage remains near battery voltage during entire 5 seconds, turn ignition off. Disconnect SBEC 60-pin connector. Check 60-pin connector for loose terminals (push-outs).

Scheme 7

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. Always refer to Emissions Control Information label in engine compartment before servicing. If manual and emission label specifications differ, always use specifications on emission label. For adjustment procedures, see ADJUSTMENTS article.

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to appropriate G - TESTS W/ CODES 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.