Engine Controls - Tests W/codes - 4.0L: 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.

RETRIEVING CODES

Note. Manufacturer recommends using DRB-II (Diagnostic Readout Box-II) to diagnose the system. See DIAGNOSIS WITH DRB-II & JEEP ADAPTER for complete diagnostic instructions.

Obtaining Fault Codes

1. Ensure ignition is off. Attach DRB-II to engine diagnostic connector. Connector is located on left side of engine compartment, near SBEC-II. (Scheme 94) Start engine (if possible). Turn A/C switch on, then off (if equipped).
2. Turn engine off. Without starting engine, turn ignition on and access READ FAULTS function of DRB-II FUEL/IGN MENU. See DRB-II DIAGNOSTIC MODE under «DIAGNOSIS WITH DRB-II & JEEP ADAPTER»(ref-24387-S18711782202001010500000) if necessary.
3. Record all fault messages displayed by DRB-II, and observe CHECK ENGINE light on instrument cluster. CHECK ENGINE light should come on for 3 seconds and then go out (bulb check).

Scheme 94

Scheme 95

Scheme 96

Scheme 97

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. Sync Signal - Displays operation of sync signal on 4.0L engines. If no sync signal is present, DRB-II will display "NO SYNC SIGNAL". 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 98

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

Fault 1000: Circuit Diagram Ignition Circuit Low. Scheme 99

Fault 1000: Flow Chart Ignition Circuit Low. Scheme 100

Fault 1001: Flow Chart Ignition Circuit High. Scheme 101

Fault 1002: Circuit Diagram O2 Heater Circuit Low. Scheme 102

Fault 1002: Flow Chart O2 Heater Circuit Low. Scheme 103

Fault 1004: Circuit Diagram Battery Voltage Low. Scheme 104

Fault 1004: Flow Chart Battery Voltage Low. Scheme 105

Fault 1005: Circuit Diagram Sensor Ground Circuit Out of Limits. Scheme 106

Fault 1005: Flow Chart Sensor Ground Circuit Out of Limits. Scheme 107

Fault 1013: Circuit Diagram Ignition Circuit High. Scheme 108

Fault 1013: Flow Chart Ignition Circuit High. Scheme 109

Fault 1014: Flow Chart Fuel Pump Circuit Low (1 Of 2). Scheme 110

Fault 1014: Flow Chart Fuel Pump Circuit Low (2 Of 2). Scheme 111

Fault 1015: Flow Chart Fuel Pump Circuit High (1 Of 2). Scheme 112

Fault 1015: Flow Chart Fuel Pump Circuit High (2 Of 2). Scheme 113

Fault 1016: Flow Chart MAT Circuit Low. Scheme 114

Fault 1017: Flow Chart MAT Circuit High. Scheme 115

Fault 1018: Circuit Diagram Serial Data Circuit. Scheme 116

Fault 1018: Flow Chart Serial Data Circuit. Scheme 117

Fault 1020: Circuit Diagram No Sync Pulse Seen. Scheme 118

Fault 1020: Flow Chart No Sync Pulse Seen (1 of 3). Scheme 119

Fault 1020: Flow Chart No Sync Pulse Seen (2 of 3). Scheme 120

Fault 1020: Flow Chart No Sync Pulse Seen (3 of 3). Scheme 121

Fault 1021: Circuit Diagram Engine Failed To Start. Scheme 122

Fault 1021: Flow Chart Engine Failed To Start (1 of 3). Scheme 123

Fault 1021: Flow Chart Engine Failed To Start (2 of 3). Scheme 124

Fault 1021: Flow Chart Engine Failed To Start (3 of 3). Scheme 125

Fault 1022: Circuit Diagram Starter Relay Circuit Low. Scheme 126

Fault 1022: Flow Chart Starter Relay Circuit Low. Scheme 127

Fault 1027: Flow Chart ECU Sees Wide Open Throttle. Scheme 128

Fault 1028: Flow Chart ECU Doesn't See Wide Open Throttle. Scheme 129

Fault 1031: Circuit Diagram ECU Sees Closed Throttle (For 1 of 3). Scheme 130

Fault 1031: Flow Chart ECU Sees Closed Throttle (1 of 3). Scheme 131

Fault 1031: Flow Chart ECU Sees Closed Throttle (2 of 3). Scheme 132

Fault 1031: Flow Chart ECU Sees Closed Throttle (3 of 3). Scheme 133

Fault 1032: Flow Chart ECU Doesn't See Closed Throttle (1 of 2). Scheme 134

Fault 1032: Flow Chart ECU Doesn't See Closed Throttle (2 of 2). Scheme 135

Fault 1037: Flow Chart TPS Circuit Low (1 of 3). Scheme 136

Fault 1037: Flow Chart TPS Circuit Low (2 of 3). Scheme 137

Fault 1037: Flow Chart TPS Circuit Low (3 of 3). Scheme 138

Fault 1038: Circuit Diagram Park/Neutral Circuit High (A/T). Scheme 139

Fault 1038: Flow Chart Park/Neutral Circuit High (A/T). Scheme 140

Fault 1039: Flow Chart Park/Neutral Circuit Low (A/T). Scheme 141

Fault 1040: Circuit Diagram Latched B+ Circuit Low. Scheme 142

Fault 1040: Flow Chart Latch ED B+ Circuit Low. Scheme 143

Fault 1041: Flow Chart Latched B+ Circuit High. Scheme 144

Fault 1042: Flow Chart No Latched B+ 1/2 Volt Drop (1 of 2). Scheme 145

Fault 1042: Flow Chart No Latched B+ 1/2 Volt Drop (2 of 2). Scheme 146

Fault 1044: Circuit Diagram Shift Light Circuit (M/T). Scheme 147

Fault 1044: Flow Chart Shift Light Circuit. Scheme 148

Fault 1047: Flow Chart Wrong ECU. Scheme 149

Fault 1048: Flow Chart M/T Vehicle With A/T ECU. Scheme 150

Fault 1049: Flow Chart A/T Vehicle With M/T ECU. Scheme 151

Fault 1050: Flow Chart Idle RPM Less Than 500. Scheme 152

Fault 1051: Flow Chart Idle RPM Greater Than 2000 (1 of 2). Scheme 153

Fault 1051: Flow Chart Idle RPM Greater Than 2000 (2 of 2). Scheme 154

Fault 1052: Flow Chart MAP Sensor Out of Limits (1 of 2). Scheme 155

Fault 1052: Flow Chart MAP Sensor Out of Limits (2 of 2). Scheme 156

Fault 1053: Flow Chart Change in MAP Reading Out of Limits (1 of 2). Scheme 157

Fault 1053: Flow Chart Change in MAP Reading Out of Limits (2 of 2). Scheme 158

Fault 1054: Flow Chart Coolant Temp Sensor Circuit Low. Scheme 159

Fault 1055: Flow Chart Coolant Temp Sensor Circuit High. Scheme 160

Fault 1056: Flow Chart Inactive Coolant Temp Sensor. Scheme 161

Fault 1057: Circuit Diagram Knock Circuit Shorted. Scheme 162

Fault 1057: Flow Chart Knock Circuit Shorted (1 of 2). Scheme 163

Fault 1057: Flow Chart Knock Circuit Shorted (2 of 2). Scheme 164

Fault 1058: Flow Chart Knock Value Out of Limits (1 of 2). Scheme 165

Fault 1058: Flow Chart Knock Value Out of Limits (2 of 2). Scheme 166

Fault 1059: Circuit Diagram A/C Request Circuit Low. Scheme 167

Fault 1059: Flow Chart A/C Request Circuit Low. Scheme 168

Fault 1060: Flow Chart A/C Request Circuit High. Scheme 169

Fault 1061: Flow Chart A/C Select Circuit Low (1 of 2). Scheme 170

Fault 1061: Flow Chart A/C Select Circuit Low (2 of 2). Scheme 171

Fault 1062: Flow Chart A/C Select Circuit High (1 of 3). Scheme 172

Fault 1062: Flow Chart A/C Select Circuit High (2 of 3). Scheme 173

Fault 1062: Flow Chart A/C Select Circuit High (3 of 3). Scheme 174

Fault 1063: Flow Chart A/C Clutch Circuit Low (1 of 3). Scheme 175

Fault 1063: Flow Chart A/C Clutch Circuit Low (2 of 3). Scheme 176

Fault 1063: Flow Chart A/C Clutch Circuit Low (3 of 3). Scheme 177

Fault 1064: Flow Chart A/C Clutch Circuit High. Scheme 178

FAULT 1065: O2 SENSOR READS RICH

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

Fault 1065: Flow Chart O2 Sensor Reads Rich. Scheme 179

FAULT 1066: O2 SENSOR READS LEAN

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

Fault 1066: Flow Chart O2 Sensor Reads Lean. Scheme 180

Fault 1067: Flow Chart Latch Relay Circuit Low. Scheme 181

Fault 1068: Flow Chart Latch Relay Circuit High. Scheme 182

Fault 1069: Flow Chart No Tach. Scheme 183

Fault 1073: Circuit Diagram ECU Doesn't See Speed Sensor. Scheme 184

Fault 1073: Flow Chart ECU Doesn't See Speed Sensor (1 of 2). Scheme 185

Fault 1073: Flow Chart ECU Doesn't See Speed Sensor (2 of 2). Scheme 186

Fault 1200: Flow Chart Defective ECU or Short To Voltage (1 of 5). Scheme 187

Fault 1200: Flow Chart Defective ECU or Short To Voltage (2 of 5). Scheme 188

Fault 1200: Flow Chart Defective ECU or Short To Voltage (3 of 5). Scheme 189

Fault 1200: Flow Chart Defective ECU or Short To Voltage (4 of 5). Scheme 190

Fault 1200: Flow Chart Defective ECU or Short To Voltage (5 of 5). Scheme 191

Fault 1201: Flow Chart Injector Short to B+ (1 of 2). Scheme 192

Fault 1201: Flow Chart Injector Short to B+ (2 of 2). Scheme 193

Fault 1202: Flow Chart All Injectors Shorted to Ground (1 of 3). Scheme 194

Fault 1202: Flow Chart All Injectors Shorted to Ground (2 of 3). Scheme 195

Fault 1202: Flow Chart All Injectors Shorted to Ground (3 of 3). Scheme 196

Fault 1203: Flow Chart No. 1 Injector Shorted to Ground. Scheme 197

Fault 1204: Flow Chart No. 2 Injector Shorted to Ground. Scheme 198

Fault 1205: Flow Chart No. 3 Injector Shorted to Ground. Scheme 199

Fault 1206: Flow Chart No. 4 Injector Shorted to Ground. Scheme 200

Fault 1207: Flow Chart No. 5 Injector Shorted to Ground. Scheme 201

Fault 1208: Flow Chart No. 6 Injector Shorted to Ground. Scheme 202

Fault 1209: Flow Chart All Injector Open (1 of 6). Scheme 203

Fault 1209: Flow Chart All Injector Open (2 of 6). Scheme 204

Fault 1209: Flow Chart All Injector Open (3 of 6). Scheme 205

Fault 1209: Flow Chart All Injector Open (4 of 6). Scheme 206

Fault 1209: Flow Chart All Injector Open (5 of 6). Scheme 207

Fault 1209: Flow Chart All Injector Open (6 of 6). Scheme 208

Fault 1210: Flow Chart No. 1 Injector Circuit Open. Scheme 209

Fault 1211: Flow Chart No. 2 Injector Circuit Open. Scheme 210

Fault 1212: Flow Chart No. 3 Injector Circuit Open. Scheme 211

Fault 1213: Flow Chart No. 4 Injector Circuit Open. Scheme 212

Fault 1214: Flow Chart No. 5 Injector Circuit Open. Scheme 213

Fault 1215: Flow Chart No. 6 Injector Circuit Open. Scheme 214

Fault 1216: Flow Chart No Voltage At ECU From A/C Relay. Scheme 215

Fault 1217: Flow Chart No Voltage At ECU From O2 Heater Relay. Scheme 216

Fault 1218: Flow Chart No Voltage At ECU From Power Latch Relay. Scheme 217

Fault 1219: Flow Chart No Voltage At ECU From Shift Light. Scheme 218

Fault 1220: Circuit Diagram No Voltage At ECU From EGR Solenoid. Scheme 219

Fault 1220: Flow Chart No Voltage At ECU From EGR Solenoid. Scheme 220

Fault 1222: Flow Chart Ignition Module Not Grounded (1 of 2). Scheme 221

Fault 1222: Flow Chart Ignition Module Not Grounded (2 of 2). Scheme 222

Fault 1223: Flow Chart Checking For Open Injector Feed Circuit. Scheme 223