SYSTEM DIAGNOSIS
Use Chrysler Motors code charts when using Chrysler's Diagnostic Readout Box (DRB-II). If DRB-II is not available, system diagnosis can be accomplished using a voltmeter. To perform self-diagnostics using a voltmeter, see RETRIEVING CODES (USING VOLTMETER) .
Note. Chrysler Motors recommends using DRB-II to diagnose system. Voltmeter usage has limited diagnostic capabilities, but can be used if DRB-II is not available.
Engine Control Unit (ECU) monitors several different engine control system circuits. If an abnormal input signal occurs, a fault code is stored in ECU memory and given a fault code number. Each circuit has its own fault number and message. A fault code does not condemn any specific component; it simply points out a probable malfunctioning area.
Fault codes can be confirmed by using a voltmeter or Chrysler's Diagnostic Readout Box (DRB-II). See RETRIEVING CODES (USING VOLTMETER) or RETRIEVING CODES (USING DRB-II) . By using DRB-II, self-diagnostic capabilities of this system can simplify testing and reduce diagnostic time.
System malfunctions encountered are identified as either hard failures or intermittent failures as determined by ECU.
PRETEST INSPECTION
Before proceeding with diagnosis, following precautions must be observed
- Vehicle must have a fully charged battery and functional charging system.
- Visually inspect connectors and circuit wiring being worked on.
- DO NOT disconnect battery or ECU. This will erase any fault codes stored in ECU.
- DO NOT cause short circuits when performing electrical tests. This will set additional fault codes, making diagnosis of original problem more difficult.
- DO NOT use a test light in place of a voltmeter.
- When checking for spark, ensure coil wire is NOT more than 1/4" from ground. If coil wire is more than 1/4" from ground, damage to vehicle electronics and/or ECU may result.
- DO NOT prolong testing of fuel injectors. Engine may hydrostatically (liquid) lock.
- When a vehicle has multiple fault codes, always repair lowest number fault code first.
- If using DRB-II to diagnose system, always perform verification test after repairs are made.
DIAGNOSTIC PROCEDURE (USING DRB-II)
Note. When using diagnostic code charts, DO NOT skip any steps in chart or incorrect diagnosis may result. Always check related Technical Service Bulletins (TSBs).
Refer to RETRIEVING CODES (USING DRB-II) to retrieve fault codes. If fault codes are NOT present and DRB-II is used, proceed to one of the following tests
- Go to NO START TEST 1 (NS-1) chart if a no-start condition exists or engine stalls after start-up. Perform indicated VERIFICATION PROCEDURE chart (when provided) after repairs. Ensure charts apply to engine being tested.
- Go to DRIVEABILITY TEST 1 (DR-1) chart if engine runs but has performance problems. Perform indicated VERIFICATION TEST chart (when provided) after repairs. Ensure charts apply to engine being tested.
DR-16: NO FAULT CODE SENSOR TEST
| DRB-II EGR Temp. Display | Engine Condition |
|---|---|
| 160°F | Hot Idle (198°F Coolant) |
| 350°F | 25 MPH at 3500 RPM |
| 311°F | 55 MPH at 3500 RPM |
DR-16 EGR TEMP SENSOR TEST
DR-16 Test Flow Chart (1 Of 5) No Fault Code Sensor Test. Scheme 1
| Altitude (Ft) | DRB-II BARO Reading (in. HG) |
|---|---|
| 1000 | 31.01 |
| 900 | 30.90 |
| Sea Level | 29.92 |
| 500 | 29.38 |
| 1000 | 28.85 |
| 1500 | 28.33 |
| 2000 | 27.82 |
| 3000 | 26.81 |
| 4000 | 25.84 |
| 6000 | 23.97 |
| 8000 | 22.22 |
| 10,000 | 20.57 |
| 12,000 | 19.02 |
| 14,000 | 17.57 |
DR-16 BARO SENSOR TEST
DR-16 Test Flow Chart (2 Of 5) No Fault Code Sensor Test. Scheme 2
DR-16 Test Schematic - ISC Motor No Fault Code Sensor Test. Scheme 3
DR-16 Test - ISC Motor Test Diagram No Fault Code Sensor Test. Scheme 4
DR-16 Test Flow Chart (3 Of 5) No Fault Code Sensor Test. Scheme 5
DR-16 Test Schematic - Power Steering Switch No Fault Code Sensor Test. Scheme 6
DR-16 Test Flow Chart (4 Of 5) No Fault Code Sensor Test. Scheme 7
DR-16 Test Flow Chart (5 Of 5) No Fault Code Sensor Test. Scheme 8
DR-17 Test Schematic Testing Purge Solenoid Circuit. Scheme 9
DR-17 Test Flow Chart Testing Purge Solenoid Circuit. Scheme 10
DR-18: NO FAULT CODE MECHANICAL TEST
At this point in the driveability test procedure, you have determined that all of the engine control systems are operating as the were designed to. Therefore, they are not the cause of the driveability problem.
The following additional items can not be overlooked as possible cause of a driveability problem.
- THROTTLE VALVE AREA - Dirt or ice buildup causing rough idle and stalling.
- ENGINE IGNITION TIMING - Must be set with timing terminal grounded.
- ENGINE VACUUM - Must be normal for your altitude.
- ENGINE VALVE TIMING - To specifications.
- ENGINE COMPRESSION - To specifications.
- ENGINE P.C.V. SYSTEM - Must flow freely.
- ENGINE EXHAUST SYSTEM - Must be free of any restrictions.
- POWER BRAKE BOOSTER - No internal vacuum leaks.
- TORQUE CONVERTER CONDITION - May cause very low power at breakaway or high speed (Only 1 condition at a time).
- FUEL CONTAMINATION - High alcohol or water content.
- FUEL INJECTORS - Rough idle may be caused by injector wiring not connected to correct injector.
- ENGINE SECONDARY IGNITION CHECK - Abnormal scope patterns.
- TECHNICAL SERVICE BULLETINS - Any that apply to vehicle.
- All air intake piping and vacuum hoses must be in place and secure. The proper air filter element must be used.
- FUEL PRESSURE - Must be correct. Specification: With no vacuum at the regulator: 48 PSI on V6 & non-turbo 4 Cyl. engines and 36 PSI on turbo engines.