Engine Controls - Tests W/codes - V8: Diagnosis Dodge Cab & Chassis Dakota

SYSTEM DIAGNOSIS

The self-diagnostic capabilities of this system, if properly utilized, can simplify testing. The Single-Board Engine Controller (SBEC) monitors several different engine control system circuits.

If a problem is sensed with a monitored circuit, a fault code is stored in the SBEC, the CHECK ENGINE light illuminates, and SBEC enters limp-in mode. In limp-in mode, SBEC compensates for component failure by substituting information from other sources. This allows vehicle operation until repairs can be made.

Once fault codes are known, refer to FAULT CODES table in this article to determine the questionable circuit. Test circuits and repair or replace components as required. If problem is repaired or ceases to exist, the SBEC cancels that fault code after approximately 50 ignition on-off cycles. To clear fault codes, see CLEARING FAULT CODES in this article.

A specific fault code is the result of a particular system failure, but it DOES NOT indicate that cause of failure is necessarily within system. The fault code DOES NOT condemn any specific component; it pinpoints a probable malfunctioning area.

DIAGNOSTIC PROCEDURE

To obtain fault codes, see RETRIEVING FAULT CODES in this article. If fault codes are NOT present and/or Diagnostic Readout Box II (DRB-II) is used, proceed to one of the following tests.

1. Go to NO START TEST 1A (NS-1A) chart if a no-start condition exists, or engine stalls after start-up. Perform indicated VERIFICATION PROCEDURE chart after repairs. Ensure charts apply to engine being tested.
2. Go to DRIVEABILITY TEST 1A (DR-1A) chart if engine runs but has performance problems. Perform indicated VERIFICATION PROCEDURE chart after repairs. Ensure charts apply to engine being tested.

Note. When using trouble shooting charts for diagnosis, DO NOT skip any steps in chart, or incorrect diagnosis may result.

Before proceeding with diagnosis, the following precautions must be followed

1. Vehicle must have a fully charged battery, and functional charging system.
2. Probe SBEC connector from pin side. DO NOT backprobe SBEC connector.
3. DO NOT cause short circuits when performing electrical tests. This will set additional fault codes, making diagnosis of original problem more difficult.
4. DO NOT use a test light in place of a voltmeter.
5. When checking for spark, ensure coil wire is NO more than 1/4" from ground. If coil wire is more than 1/4" from ground, damage to vehicle electronics and/or SBEC may result.
6. DO NOT prolong testing of fuel injectors, or engine may hydrostatically (liquid) lock.
7. Always repair lowest fault code number (CHECK ENGINE light), or first fault displayed (DRB-II) first.
8. Always perform VERIFICATION PROCEDURE test after repairs are made.
9. Always disconnect DRB-II after use.
10. Always disconnect DRB-II before charging battery.

ACTUATOR TEST MODE

Actuator test mode is used to check operation of output circuits of devices the SBEC cannot recognize. The following, depending on engine and model application, can be activated in actuator test mode to ensure component operation: relays, solenoids and various components. The following are information or components that may be accessed through actuator test mode.

1. A/C Clutch Relay
2. Air Idle Speed (AIS) Motor
3. Air Switch Solenoid
4. Alternator Field
5. ASD (Auto Shutdown) Relay
6. ASD (Auto Shutdown) System
7. CHECK ENGINE Light
8. EGR Solenoid
9. Emission Maintenance Reminder (EMR) Light
10. Fuel Injector
11. Ignition Coil
12. Overdrive Solenoid
13. Part Throttle Unlock (PTU) A/T Only
14. Purge Solenoid
15. Radiator Fan Relay
16. Shift Indicator Light (M/T Only)
17. Solenoid/Relays
18. Speed Control Servo Solenoids
19. Stop All Tests
20. Tachometer Output

KEYPAD TEST FAILURE

Ensure ignition is off. DO NOT touch keypad on DRB-II. Turn ignition on. If DRB-II displays KEYPAD TEST FAILURE, replace DRB-II. If KEYPAD TEST FAILURE message is not displayed, proceed with diagnostics.

RAM TEST FAILURE

If message is displayed, replace DRB-II and proceed with diagnostics.

DR-45A PERFORMING NO FAULT CODE MECHANICAL TEST

At this point in the driveability test procedure, it has been determined that all engine control systems are operating as designed and are not the cause of the driveability problem. Check the following additional items for possible causes

1. Valve timing.
2. Torque converter stall speed.
3. Engine compression.
4. Camshaft and crankshaft sprockets.
5. Power brake booster for internal vacuum leaks.
6. For fuel contamination.
7. Exhaust system for restriction.
8. Ensure injectors are not plugged or restricted.
9. Ensure engine vacuum is at least 13 in. Hg.
10. Ensure PCV system is functioning properly.

Test DR-46A Intermittent Test for Solenoids & Relays. Scheme 168

Test DR-47A Intermittent Test for Voltage Sensors. Scheme 169

Test DR-47B Intermittent Test for MAP Sensor Signal Change. Scheme 170

Test DR-48A Intermittent Test for AIS Motor Circuits. Scheme 171

Test DR-49A Intermittent Test for Fuel Injectors. Scheme 172