Engine Controls - Tests W/codes - 2.5L: Other Jeep Cherokee II

HARD FAILURES

Hard failures cause "malfunction" light to illuminate and remain on until the malfunction is repaired. If light comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined using diagnostic (code) charts. If a sensor fails, control unit will use a substitute value in its calculations to continue engine operation. In this condition, vehicle is functional, but loss of good driveability will most likely be encountered.

INTERMITTENT FAILURES

Intermittent failures may cause "malfunction" light to flicker or illuminate and go out after the intermittent fault goes away. The corresponding trouble code, however, will be retained in control unit memory. If related fault does not reoccur within a certain time frame, related trouble code will be erased from control unit memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES article.

Scheme 5

Scheme 6

PRELIMINARY CHECKS

Most driveability problems in the engine control system result from faulty wiring or leaking hose connections. To avoid unnecessary component testing, a visual check should be performed before beginning trouble shooting procedures to help spot these common faults.

ECU CHECKOUT PROCEDURE

1. If during testing the Electronic Control Unit (ECU) is found to be faulty, perform the following steps to ensure control unit is faulty. Most components are incorrectly diagnosed due to faulty electrical connectors or a poor mechanical connection between component and vehicle.
2. Sometimes simply disconnecting and reconnecting an electrical component will provide a good electrical connection. Before replacing a control unit, check all components in the suspected circuit. If other components are okay, carefully disconnect control unit from vehicle harness.
3. Inspect control unit harness connector and control unit contact pins for corrosion. Clean harness connector and control unit contact pins with contact cleaner. Inspect control unit harness connector for bent pins, missing pins and broken wires. Repair or replace as necessary.
4. Connect control unit harness connector to control unit and retest system with DRB-II and adapter. If vehicle does not pass test and fails with the same message, replace control unit.

DRB-II JEEP PROBLEMS

The most common problem is a blank screen. If after connecting DRB-II to vehicle, screen is blank, check the following

1. Ensure all connections are proper and fit correctly.
2. Ensure wires in cables are not broken or shorted.
3. Ensure diagnostic connector has power available to adaptor.
4. Ensure cartridge is firmly installed in DRB-II.

If a defective DRB-II is encountered, generally the screen should not be blank when everything is connected the first time. Trying DRB-II with adaptor on another Jeep vehicle may help to isolate a faulty component.

JEEP DRB-II ADAPTER

To properly interface with Jeep vehicles, an adapter must be attached to the DRB-II. The adapter is required as diagnostics on Jeep products are performed Off-Board. The adapter converts signals into a form the DRB-II can utilize in performing tests. Itself a powerful computer, the adapter MUST be used with the DRB-II when diagnosing Jeep vehicles.

The ECU has been programmed to monitor several different circuits of the engine control system. If a problem is sensed with a monitored circuit, a fault code is stored in the ECU.

The setting of a specific fault code is the result of a particular system failure, NOT the reason for that failure, such as failure of a specific component. The existence of a particular code denotes the probable area of the malfunction, not necessarily the failed component itself.

With DRB-II connected to Jeep adapter and Jeep adapter connected to both vehicle diagnostic connectors, all character positions will illuminate and copyright information will appear on screen. The DRB-II will offer 3 menus: VEHICLES TESTED, HOW TO USE and SELECT VEHICLE.

VEHICLES TESTED

To enter VEHICLES TESTED, press "1" key or ENTER key when VEHICLES TESTED appears on DRB-II display. DRB-II will show vehicles supported with cartridge used. This screen will display for 5 seconds and return to DRB-II menu. To return to DRB-II menu sooner, press ATM key.

HOW TO USE

To enter HOW TO USE menu option, press "2" key or press downward facing arrow button to display HOW TO USE option. Press ENTER key. DRB-II will display instructions for use of DRB-II with cartridge being used.

SELECT VEHICLE

1. The SELECT VEHICLE option provides a means which the user may enter information about vehicle being tested. Usually this option will have more than one display screen. Use ENTER key to enter vehicle information. If an option is not available for vehicle being tested, DRB-II will not display that option.
2. When all information about the vehicle is entered, DRB-II will display a summary of information technician entered as a confirming menu. DRB-II will show an additional option marked CONFIRM. If information is correct, press CONFIRM. DRB-II will display MAIN MENU.

MAIN MENU

The MAIN MENU will present all diagnostic functions available for vehicle selected. Functions are SYSTEM TESTS, STATE DISPLAYS and ADJUSTMENTS.

STATE DISPLAYS

1. This display enables technician to view conditions at the signal level. The 2 types of signals used are analog and digital. Analog signals are monitored at pins corresponding to vehicle harness splices (e.g. fuel pump relay). Digital signals correspond to data transmitted by the system controllers. Both signals are displayed in common units (e.g. temperature), this information is not relative to diagnostic intent.
2. Use up and down arrow keys on DRB-II to scroll through displays available. When STATE DISPLAY is selected, a menu showing systems for which state displays are supported is displayed. If ENGINE state display is selected, technician has the option to view either static state displays or MAX/CURRENT/MIN value display.
3. The STATIC display shows conditions as they exist at the time the user is viewing the display. The MIN/CURRENT/MAX display shows a history of conditions for specific sensor. When this option is selected, maximum, current (static) and minimum value can be displayed for a specific sensor. To reset sensors to a zero value, simply press ENTER KEY. This display may be used to isolate intermittent faults.
4. The following ENGINE state displays are available on the DRB-II. Vehicle Program and Calibration Code - Program numbers indicate the ECU is programmed for a specific engine. Calibration code applies to manual or automatic transmission. Battery - Displays battery voltage. H2O - Engine coolant temperature is displayed in degrees Fahrenheit and Celsius. Air - Air temperature is displayed in degrees Fahrenheit and Celsius. TPS - Throttle Position Sensor (TPS) is displayed as WIDE OPEN, CLOSED or PARTIAL and percentage of opening from closed throttle to Wide Open Throttle (WOT). A/C Status - If any of the A/C signals are active, an abbreviated display showing A/C state will be displayed as select SELL, predict PRE, clutch CL and cut-out CO. If A/C signals are inactive, A/C OFF will be displayed. Relay Status - Displays EGR solenoid, B+ latch relay and fuel pump control relay as on "+" or off "0". When EGR solenoid is off, vacuum is present. When EGR solenoid is on, vacuum is absent. Barometric Pressure Reading - Barometric pressure value can be used to test MAP sensor. A good MAP sensor will read within .60 in. Hg of current barometric pressure at sea level. Subtract .1 in. Hg for every 100 feet above sea level. Current barometric pressure may be obtained from your local weather bureau. RPM - Engine speed is displayed. Exhaust Oxygen Sensor - Displays voltage from O2 sensor and whether fuel system is RICH or LEAN. Displays if system is in DECEL condition or in OPEN LOOP. Pulse Width - Displays the amount of time in milliseconds that the fuel injector is open. Knock - Displays knock sensor noise volume in units from 0-255. If display is more than 250, this will generally indicate a short circuit. Normal readings of a functional knock sensor will be more than 5. A short to ground, open circuit or a non-functioning knock sensor will generally not cause a value above 5 to be displayed. ALFACL - The closed loop pulse width correction factor is displayed in units from 0-255. ALFACL represents the correction used to calculate injector pulse width in response to oxygen sensor input. If oxygen sensor reads rich, ALFACL will decrease. If oxygen sensor reads lean, ALFACL will increase. CTAVE - This is average closed throttle value displayed as a percentage of full scale. The closed throttle switch provides a signal to the ECU to indicate closed throttle status. KAM - Keep Alive Memory (KAM) faults are displayed for the O2 sensor, MAP sensor, TPS, air temperature sensor and coolant temperature sensor. Next to sensor display, a pair of numbers is displayed. Each number reflects a period since the ECU has detected a fault. The first number corresponds to a sensed "low" condition failure and the second number corresponds to a sensed "high" condition failure. When ECU detects a "low" or "high" condition failure, then number "15" will be stored for the respective sensor. If the engine is started and closed loop is attempted and fault is no longer present, the counter will be decreased by one. If the fault is still present, counter will remain at 15. Values of "0" (zero) are an indication that a "low" or "high" fault condition does not exist for the sensor displayed. Values less than 15 and greater than zero are an indication that the ECU has detected a fault at some time, but fault is not present during the current start cycle (possible intermittent). Warranty - A 6-digit code for warranty reporting.
5. The Min/Current/Max display allows technician to observe operation of 6 different sensor values. Information is displayed as a 3 digit number. The first value displayed is the minimum reading, second number displayed is current reading and third value displayed is the maximum reading. The sensors that are monitored are: MAP sensor, O2 sensor, Throttle Position Sensor (TPS), Coolant Temperature Sensor (CTS), Manifold Air Temperature (MAT) sensor and CTAVG (average learned closed throttle value).
6. Typically sensors range between 2-252. Values less than 2 or greater than 252 will usually indicate that a sensor is shorted or disconnected. Watch minimum and maximum values to help diagnose intermittent problems.

CLEARING CODES

The Adjustments option provides TPS adjustment or erasing stored information in system controller. Follow DRB-II instructions to accomplish desired task.

SUMMARY

If no hard fault codes (or only pass codes) are present, driveability symptoms exist or intermittent codes exist, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.), or intermittent diagnostic procedures.

Scheme 7

Note. The following schematics and charts are courtesy of Chrysler Motors.

Fault 1000: Circuit Diagram Ignition Circuit Low. Scheme 8

Fault 1000: Flow Chart Ignition Circuit Low. Scheme 9

Fault 1001: Flow Chart Ignition Circuit High. Scheme 10

Fault 1004: Circuit Diagram ECU Battery Feed & Power Grounds. Scheme 11

Fault 1004: Flow Chart ECU Battery Feed & Power Grounds. Scheme 12

Fault 1005: Flow Chart System Ground Circuit. Scheme 13

Fault 1006: Circuit Diagram EGR Solenoid Circuit Low. Scheme 14

Fault 1006: Flow Chart EGR Solenoid Circuit Low. Scheme 15

Fault 1007: Flow Chart EGR Solenoid Circuit Low. Scheme 16

Fault 1008: Circuit Diagram Power Steering Circuit Low. Scheme 17

Fault 1008: Flow Chart Power Steering Circuit Low. Scheme 18

Fault 1009: Flow Chart Power Steering Circuit High. Scheme 19

Fault 1012: Circuit Diagram Fuel Injector Circuits. Scheme 20

Fault 1012: Flow Chart Fuel Injector Circuits. Scheme 21

Fault 1013: Circuit Diagram Ignition Module (MPA) Circuit High. Scheme 22

Fault 1013: Flow Chart Ignition Module (MPA) Circuit High. Scheme 23

Fault 1014: Flow Chart Fuel Pump Circuit Low. Scheme 24

Fault 1015: FLow Chart Fuel Pump Circuit High. Scheme 25

Fault 1016: Circuit Diagram MAT Circuit Low. Scheme 26

Fault 1016: Flow Chart MAT Circuit Low. Scheme 27

Fault 1017: Flow Chart MAT Circuit High. Scheme 28

Fault 1018: Circuit Diagram Serial Data Circuit (A/T). Scheme 29

Fault 1018: Flow Chart Serial Data Circuit (A/T). Scheme 30

Fault 1018: Flow Chart Serial Data Circuit (M/T). Scheme 31

Fault 1019: Flow Chart Power Latch Not Set. Scheme 32

Fault 1021: Circuit Diagram Engine Failed To Start. Scheme 33

Fault 1021: Flow Chart Engine Failed To Start (1 of 2). Scheme 34

Fault 1021: Flow Chart Engine Failed To Start (2 of 2). Scheme 35

Fault 1022: Circuit Diagram Starter Relay Circuit Low. Scheme 36

Fault 1022: Flow Chart Starter Relay Circuit Low. Scheme 37

Fault 1024: Flow Chart ECU Start Circuit Low. Scheme 38

Fault 1027: Circuit Diagram TPS Circuit High. Scheme 39

Fault 1027: Flow Chart TPS Circuit High. Scheme 40

Fault 1028: Flow Chart Checking TPS Calibration. Scheme 41

Fault 1029: Circuit Diagram ISA Closed Throttle Circuit Low. Scheme 42

Fault 1029: Flow Chart ISA Closed Throttle Circuit Low. Scheme 43

Fault 1030: Flow Chart ISA Closed Throttle Circuit High. Scheme 44

Fault 1031: Flow Chart ECU Closed Throttle Circuit Low. Scheme 45

Fault 1032: Flow Chart ECU Closed Throttle Circuit High. Scheme 46

Fault 1033-36: Circuit Diagram ISA Circuits. Scheme 47

Fault 1033-36: Flow Chart ISA Circuits (1 of 2). Scheme 48

Fault 1033-36: Flow Chart ISA Circuits (2 Of 2). Scheme 49

Fault 1037: Circuit Diagram TPS Circuit Low. Scheme 50

Fault 1037: Flow Chart TPS Circuit Low. Scheme 51

Fault 1038: Flow Chart Serial Data Enable Circuit High. Scheme 52

Fault 1039: Flow Chart Serial Data Enable Circuit Low. Scheme 53

Fault 1040: Circuit Diagram Power Latch Relay Circuit Low. Scheme 54

Fault 1040: Flow Chart Power Latch Relay Circuit Low. Scheme 55

Fault 1041: Flow Chart Power Latch Relay Circuit High. Scheme 56

Fault 1042: Flow Chart Charging & ECU Circuits. Scheme 57

Fault 1043: Circuit Diagram Shift Light Circuit Low. Scheme 58

Fault 1043: Flow Chart Shift Light Circuit Low. Scheme 59

Fault 1044: Circuit Diagram D2-1 Circuit Low (A/T). Scheme 60

Fault 1044: Flow Chart D2-1 Circuit Low (A/T). Scheme 61

Fault 1044: Flow Chart Upshift Light Circuit (M/T). Scheme 62

Fault 1048: Flow Chart Checking M/T Vehicle For Correct ECU. Scheme 63

Fault 1048: Flow Chart Checking M/T Vehicle For Correct ECU. Scheme 64

Fault 1050: Circuit Diagram Idle RPM Low. Scheme 65

Fault 1050: Flow Chart Idle RPM Low. Scheme 66

Fault 1051: Flow Chart Idle RPM High. Scheme 67

Fault 1052: Flow Chart MAP Sensor Circuit Low. Scheme 68

Fault 1053: Flow Chart MAP Sensor Ground Circuit. Scheme 69

Fault 1054: Circuit Diagram Coolant Sensor & 5-Volt Supply To TPS/MAP Circuit Low (For 1 of 2). Scheme 70

Fault 1054: Flow Chart Coolant Sensor & 5-Volt Supply To TPS/MAP Circuit Low (1 Of 2). Scheme 71

Fault 1054: Flow Chart Coolant Sensor & 5-Volt Supply To TPS/MAP Circuit Low (2 Of 2). Scheme 72

Fault 1055: Flow Chart Coolant Sensor Circuit High. Scheme 73

Fault 1056: Flow Chart Inactive Coolant Temperature Sensor. Scheme 74

Fault 1059: Circuit Diagram A/C Request Circuit Low. Scheme 75

Fault 1059: Flow Chart A/C Request Circuit Low. Scheme 76

Fault 1061: Flow Chart A/C Request Circuit High. Scheme 77

Fault 1061: Flow Chart A/C Select Circuit Low (1 of 2). Scheme 78

Fault 1061: Flow Chart A/C Select Circuit Low (2 of 2). Scheme 79

Fault 1062: Flow Chart A/C Select Circuit High. Scheme 80

Fault 1063: Flow Chart A/C Clutch Circuit Low. Scheme 81

Fault 1064: Flow Chart A/C Clutch Circuit High & P/S Input (1 of 2). Scheme 82

Fault 1064: Flow Chart A/C Clutch Circuit High & P/S Input (2 of 2). Scheme 83

FAULT 1065: LEAN O2 SENSOR INPUT

Note. For additional oxygen sensor information, see TITANIA OXYGEN SENSOR TESTING article.

Fault 1065: Circuit Diagram Lean O2 Sensor Input. Scheme 84

Fault 1065: Flow Chart Lean O2 Sensor Input. Scheme 85

FAULT 1066: RICH O2 SENSOR INPUT

Note. For additional oxygen sensor information, see TITANIA OXYGEN SENSOR TESTING article.

Fault 1066: Flow Chart Rich O2 Sensor Input. Scheme 86

Fault 1067: Circuit Diagram Latch Relay Circuit Low. Scheme 87

Fault 1067: Flow Chart Latch Relay Circuit Low. Scheme 88

Fault 1068: Flow Chart Latch Relay Circuit High. Scheme 89

Fault 1069: Circuit Diagram Speed Sensor & Ignition Module (MPA) Circuits. Scheme 90

Fault 1069: Flow Chart Speed Sensor & Ignition Module (MPA) Circuits (1 Of 2). Scheme 91

Fault 1069: Flow Chart Speed Sensor & Ignition Module (MPA) Circuits (2 Of 2). Scheme 92