INTRODUCTION
Perform all steps in appropriate BASIC DIAGNOSTIC PROCEDURES article. If no fault is found while performing BASIC DIAGNOSTIC PROCEDURES, proceed with self-diagnostics. If no diagnostic trouble codes or only pass codes (system functioning properly) are found during self-diagnostics, proceed to appropriate TROUBLE SHOOTING - NO CODES article for diagnosis by symptom.
Hard Failures
Malfunction Indicator Light (MIL) will illuminate when a hard failure is detected and remain on until problem is repaired. If MIL comes on and remains on or flashes during vehicle operation, cause of malfunction must be determined. When most sensors fail, ECM will default to a substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, the vehicle runs but driveability will not be optimum.
Intermittent Failures
Intermittent failures may cause Malfunction Indicator Light (MIL) to flicker or illuminate and go out after the intermittent fault goes away. However, a corresponding Diagnostic Trouble Code (DTC) may be retained in ECM memory. If related fault does not reoccur within a certain time frame, related DTC will be erased from ECM memory. Intermittent failures may be caused by a sensor, connector or wiring related problems. See appropriate TROUBLE SHOOTING - NO CODES article.
INDICATOR LIGHTS
Note. On 1998 Range Rover models equipped with an advanced EVAP system, an incorrectly installed fuel filler cap may cause CHECK ENGINE MIL to illuminate.
Note. Malfunction Indicator Light (MIL) cannot be used to retrieve and display Diagnostic Trouble Codes (DTCs).
Malfunction Indicator Light (MIL)
Models are equipped with an Amber CHECK ENGINE MIL. As a bulb check, MIL will illuminate when ignition switch is turned to ON position and go out when engine starts. If ECM detects an engine operation or emissions system problem, MIL will be illuminated or flash, and a corresponding DTC will be stored in ECM memory. Not all DTCs will illuminate MIL. If MIL is on and no DTCs are in memory, problem may be intermittent. See appropriate TROUBLE SHOOTING - NO CODES article.
Emission Maintenance Reminder Light
Models are equipped with SERVICE ENGINE emission maintenance reminder light. SERVICE ENGINE light is Amber. As a bulb check, SERVICE ENGINE light will illuminate when ignition switch is turned to ON position and go out after about 3 seconds.
At specified intervals, SERVICE ENGINE light will illuminate. When light illuminates a specified California and/or Federal emission system maintenance service is required. After emission systems check is completed, SERVICE ENGINE light must be reset. See RESETTING EMISSION MAINTENANCE REMINDER LIGHT .
Resetting Emission Maintenance Reminder Light
Procedure for resetting SERVICE ENGINE light not available from manufacturer.
RETRIEVING DIAGNOSTIC TROUBLE CODES
The first digit of the Diagnostic Trouble Code (DTC) defines whether the DTC set is a Federally mandated DTC (P0xxx) or a Land Rover DTC (P1xxx). A Land Rover TestBook can retrieve and diagnose all DTCs. An OBD-II compliant scan tool can only retrieve and diagnose Federally mandated DTCs. Refer to scan tool manufacturer's user manual for specific procedures. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
FREEZE FRAME DATA
Freeze frame data indicates engine operating conditions when the first malfunction, misfire or fuel trim malfunction was detected. Freeze frame data is read using a Land Rover TestBook or an OBD-II compliant scan tool. Refer to scan tool manufacturer's user manual for specific procedure.
CLEARING TROUBLE CODES
Diagnostic Trouble Codes (DTCs) can be cleared using a Land Rover TestBook system or OBD-II compliant scan tool. Follow TestBook system or scan tool manufacturer's instructions.
DISCONNECTING BATTERY
Note. Some models may be equipped with a anti-theft alarm back-up battery. Before disconnecting main battery, turn ignition on and then off. Main battery must be disconnected within 17 seconds or anti-theft alarm will be activated using back-up battery.
Before disconnecting battery, obtain radio presets and anti-theft code for radio from vehicle owner. When radio is disconnected from battery power it will not operate when power is restored until anti-theft code is entered. See vehicle OWNER'S MANUAL for procedure. Other vehicle systems (if equipped) affected by disconnecting battery may be electric windows and sun roof, trip computer, trip odometer and remote security handsets. See vehicle OWNER'S MANUAL for system reset procedures before disconnecting battery.
RELIEVING FUEL PRESSURE
Fuel pressure can be relieved at fuel feed fitting at fuel rail or fuel filter fitting. Position cloth around fitting to catch fuel spray. Using 2 wrenches, loosen fitting. Tighten fuel filter fitting to 15 ft. lbs. (20 N.m). Tighten fuel feed fitting to 12 ft. lbs. (16 N.m).
TEST EQUIPMENT
All voltage tests should be performed using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless specifically stated differently in testing procedure. DO NOT use test lights to test circuits containing solid state devices, doing so can damage solid state devices. When instructed to use a jumper wire ensure an in-line, 5-amp fuse is included. A Land Rover TestBook system, OBD-II compliant scan tool or a Snap-On Personal Automotive Computer (PAC) can be used to diagnosis driveability problems. Follow equipment manufacturer's operating instructions. If using a Snap-On PAC, see appropriate examples of known-good wave patterns.
SUMMARY
If no Diagnostic Trouble Code (DTC) is present but a driveability problem still exists, proceed to appropriate TROUBLE SHOOTING - NO CODES article for symptom diagnostic or intermittent diagnosis procedures.
After confirming that the circuits and components of a suspect system are functioning properly and clearing DTCs, the ECM PROM may require replacement if DTCs reset. Replacement procedure not available from manufacturer.
DIAGNOSTIC TROUBLE CODE DEFINITIONS
| DTC | Definition | (1) Test Drive |
|---|---|---|
| P0101 | Mass Airflow (MAF) Sensor Circuit Out Of Range | "B" |
| P0102 | Mass Airflow (MAF) Sensor Circuit Low Input | "A" |
| P0103 | Mass Airflow (MAF) Sensor Circuit High Input | "A" |
| P0111 | Intake Air Temp. (IAT) Sensor Reading Not Changing As Expected | "C" |
| P0112 | Intake Air Temp. (IAT) Sensor Circuit Low Range Fault | "A" |
| P0113 | Intake Air Temp. (IAT) Sensor Circuit High Range Fault | "A" |
| P0116 | Coolant Temp. (ECT) Sensor Falling Temp. Fault | "A" |
| P0117 | Coolant Temp. (ECT) Sensor Circuit Low Range Fault | "A" |
| P0118 | Coolant Temp. (ECT) Sensor Circuit High Range Fault | "A" |
| P0121 | TP Sensor Signal Inconsistent With MAF, IAC, IAT Sensors & Engine Speed Signals | "B" |
| P0122 | Throttle Position (TP) Sensor Circuit Low Input | "A" |
| P0123 | Throttle Position (TP) Sensor Circuit High Input | "A" |
| P0125 | Coolant Temp. (ECT) Sensor Excessive Time To Closed Loop/No Warm-Up Fault | "B" |
| P0130 | HO2S Circuit Slow Response, Front Bank "A" (2) | "C" |
| P0131 | HO2S Circuit Low Voltage, Front Bank "A" (2) | "C" |
| P0132 | HO2S Circuit High Voltage, Front Bank "A" (2) | "C" |
| P0133 | HO2S Circuit Slow Response, Front Bank "A" (2) | "C" |
| P0136 | HO2S Circuit Slow Response, Front Bank "B" (2) | "C" |
| P0137 | HO2S Circuit Low Voltage, Rear Bank "A" (2) | "C" |
| P0138 | HO2S Circuit High Voltage, Rear Bank "A" (2) | "C" |
| P0139 | HO2S Circuit Slow Response, Rear Bank "A" (2) | "C" |
| P0150 | HO2S Circuit Slow Response, Rear Bank "A" (2) | "C" |
| P0151 | HO2S Circuit Low Voltage, Front Bank "B" (2) | "C" |
| P0152 | HO2S Circuit High Voltage, Front Bank "B" (2) | "C" |
| P0153 | HO2S Circuit Slow Response, Front Bank "B" (2) | "C" |
| P0156 | HO2S Circuit Slow Response, Rear Bank "B" (2) | "C" |
| P0157 | HO2S Circuit Low Voltage, Rear Bank "B" (2) | "C" |
| P0158 | HO2S Circuit High Voltage, Rear Bank "B" (2) | "C" |
| P0159 | HO2S Circuit Slow Response, Rear Bank "B" (2) | "C" |
| P0171 | System Too Lean Bank "A" (2) | "C" |
| P0172 | System Too Rich Bank "A" (2) | "C" |
| P0174 | System Too Lean Bank "B" (2) | "C" |
| P0175 | System Too Rich Bank "B" (2) | "C" |
| P0181 | Fuel Temp. Sensor Fault, Invalid Reading When Compared With Coolant Temp. | "A" |
| P0182 | Fuel Temp. Sensor Circuit Low Range Fault | "A" |
| P0183 | Fuel Temp. Sensor Circuit High Range Fault | "A" |
| P0201 | Fuel Injector Circuit Fault, Cylinder No. 1 | "A" |
| P0202 | Fuel Injector Circuit Fault, Cylinder No. 2 | "A" |
| P0203 | Fuel Injector Circuit Fault, Cylinder No. 3 | "A" |
| P0204 | Fuel Injector Circuit Fault, Cylinder No. 4 | "A" |
| P0205 | Fuel Injector Circuit Fault, Cylinder No. 5 | "A" |
| P0206 | Fuel Injector Circuit Fault, Cylinder No. 6 | "A" |
| P0207 | Fuel Injector Circuit Fault, Cylinder No. 7 | "A" |
| P0208 | Fuel Injector Circuit Fault, Cylinder No. 8 | "A" |
| P0300 | Misfire On Multiple Cylinders | "C" |
| P0301 | Misfire On Cylinder No. 1 | "C" |
| P0302 | Misfire On Cylinder No. 2 | "C" |
| P0303 | Misfire On Cylinder No. 3 | "C" |
| P0304 | Misfire On Cylinder No. 4 | "C" |
| P0305 | Misfire On Cylinder No. 5 | "C" |
| P0306 | Misfire On Cylinder No. 6 | "C" |
| P0307 | Misfire On Cylinder No. 7 | "C" |
| P0308 | Misfire On Cylinder No. 8 | "C" |
| P0326 | Continuous Knock on Bank "A" (2) | "B" |
| P0327 | Knock Sensor Background Noise Low, Bank "A" (2) | "B" |
| P0328 | Knock Sensor Background Noise High, Bank "A" (2) | "B" |
| P0331 | Continuous Knock Sensor on Bank "B" (2) | "B" |
| P0332 | Knock Sensor Background Noise Low, Bank "B" (2) | "B" |
| P0333 | Knock Sensor Background Noise High, Bank "B" (2) | "B" |
| P0335 | Crankshaft Position (CKP) Sensor Circuit, No Signal | "A" |
| P0336 | Crankshaft Position (CKP) Sensor Generating Poor Quality Signal | "A" |
| P0340 | Camshaft Position Sensor Circuit Fault Or Signal Timing Different From Crankshaft Position Signal | "A" |
| P0420 | Catalyst Efficiency Low, Bank "A" (2) | "C" |
| P0430 | Catalyst Efficiency Low, Bank "B" (2) | "C" |
| P0441 | EVAP Purge Control Valve Flow Fault | "C" |
| P0442 | EVAP Loss Control System, Small Leak (3) | "D" |
| P0443 | EVAP Purge Control Valve Circuit Open Or Short | "A" |
| P0446 | EVAP Canister Close Valve Malfunction (3) | "A" |
| P0451 | Fuel Tank Pressure Sensor Poor Performance (3) | "A" |
| P0452 | Fuel Tank Pressure Sensor Low Range Fault (3) | "A" |
| P0453 | Fuel Tank Pressure Sensor High Range Fault | "A" |
| P0460 | Fuel Level Sensor Circuit Fault | "A" |
| P0461 | Fuel Level Sensor Not Changing As Expected | "C" |
| P0500 | Vehicle Speed Sensor (VSS) Signal Out Of Range | "B" |
| P0506 | Idle Air Control (IAC) Low Idle Speed | "A" |
| P0507 | Idle Air Control (IAC) High Idle Speed | "A" |
| P0560 | ECM Reads Low Battery Voltage At Engine Speeds Where Generator Should Be Operating | "A" |
| P0562 | Battery Volts Read By ECM Too Low To Be Possible | "A" |
| P0563 | Battery Volts Read By ECM Too High To Be Possible | "A" |
| P0605 | ECM Self-Check Fault (Adaptation & Fault Record Memory Corrupted) | "A" |
| P1137 | HO2S Problem Switching To Rich, Sensor(s) Bank "A" (2) | "C" |
| P1138 | HO2S Problem Switching To Lean, Sensor(s) Bank "A" (2) | "C" |
| P1139 | HO2S Switching Period Too Long, Sensor(s) Bank "A" (2) | "C" |
| P1157 | HO2S Problem Switching Rich, Sensor(s) Bank "B" (2) | "C" |
| P1158 | HO2S Problem Switching Lean, Sensor(s) Bank "B" (2) | "C" |
| P1159 | HO2S Switching Period Too Long, Sensor(s) Bank "B" (2) | "C" |
| P1171 | System Too Lean Bank "A" & Bank "B" (2) | "C" |
| P1172 | System Too Rich Bank "A" & Bank "B" (2) | "C" |
| P1176 | Long Term Fuel Trim Too Lean, Banks 1 & 2 (Fuel Mass Flow Rate) | "C" |
| P1177 | Long Term Fuel Trim Too Rich, Banks 1 & 2 (Fuel Mass Flow Rate) | "C" |
| P1178 | Long Term Fuel Trim Too Lean, Banks 1 & 2 (Air Mass Flow Rate) | "C" |
| P1179 | Long Term Fuel Trim Too Rich, Banks 1 & 2 (Air Mass Flow Rate) | "C" |
| P1185 | HO2S Heater Circuit Open, Front Sensors | "C" |
| P1186 | HO2S Heater Circuit Short, Front Sensors | "C" |
| P1187 | HO2S Heater Circuit Inferred Open Circuit, Front Sensors | "C" |
| P1188 | HO2S Heater Circuit High Resistance, Front Sensors | "C" |
| P1189 | HO2S Heater Circuit Inferred Low Resistance, Front Sensors | "C" |
| P1190 | Oxygen Sensor (HO2S) Heater Circuit Low Resistance, Front Sensors | "C" |
| P1191 | HO2S Heater Circuit Open, Rear Sensors | "C" |
| P1192 | HO2S Heater Circuit Short, Rear Sensors | "C" |
| P1193 | HO2S Heater Circuit Inferred Open Circuit, Rear Sensors | "C" |
| P1194 | HO2S Heater Circuit High Resistance, Rear Sensors | "C" |
| P1195 | HO2S Heater Circuit Inferred Low Resistance, Rear Sensors | "C" |
| P1196 | HO2S Heater Circuit Low Resistance, Rear Sensors | "C" |
| P1201 | Fuel Injector Circuit Open Or Short, Cylinder No. 1 | "A" |
| P1202 | Fuel Injector Circuit Open Or Short, Cylinder No. 2 | "A" |
| P1203 | Fuel Injector Circuit Open Or Short, Cylinder No. 3 | "A" |
| P1204 | Fuel Injector Circuit Open Or Short, Cylinder No. 4 | "A" |
| P1205 | Fuel Injector Circuit Open Or Short, Cylinder No. 5 | "A" |
| P1206 | Fuel Injector Circuit Open Or Short, Cylinder No. 6 | "A" |
| P1207 | Fuel Injector Circuit Open Or Short, Cylinder No. 7 | "A" |
| P1208 | Fuel Injector Circuit Open Or Short, Cylinder No. 8 | "A" |
| P1313 | Misfire Likely To Damage Catalyst, Bank "A" (2) | "C" |
| P1314 | Misfire Likely To Damage Catalyst, Bank "B" (2) | "C" |
| P1315 | Persistent Misfires | "C" |
| P1316 | Misfire Causing Excessive Emissions | "A" |
| P1317 | ABS Rough Road Signal Line Stuck At Ground Or Open Circuit | "A" |
| P1318 | ABS Rough Road Signal Line Stuck At Battery Volts | "A" |
| P1361 | No Ign. Coil Activation, Coil 1, Cyl. Nos. 1 & 6 | "A" |
| P1362 | No Ign. Coil Activation, Coil 2, Cyl. Nos. 5 & 8 | "A" |
| P1363 | No Ign. Coil Activation, Coil 3, Cyl. Nos. 4 & 7 | "A" |
| P1364 | No Ign. Coil Activation, Coil 4, Cyl. Nos. 2 & 3 | "A" |
| P1371 | Early Ign. Coil Activation, Coil 1, Cyls. 1 & 6 | "A" |
| P1372 | Early Ign. Coil Activation, Coil 2, Cyls. 5 & 8 | "A" |
| P1373 | Early Ign. Coil Activation, Coil 3, Cyls. 4 & 7 | "A" |
| P1374 | Early Ign. Coil Activation, Coil 4, Cyls. 2 & 3 | "A" |
| P1440 | EVAP Canister Purge Control Valve Stuck Open (3) | "C" |
| P1447 | EVAP Canister Close Valve Poor Performance (3) | "D" |
| P1448 | EVAP Loss Control System, Major Leak (3) | "D" |
| P1496 | EVAP Loss Control System, Major Leak (3) | "D" |
| P1508 | Idle Air Control (IAC) Valve Stepper Motor Circuit Open | (4) |
| P1509 | Idle Air Control (IAC) Valve Stepper Motor Circuit Short | (4) |
| P1514 | Neutral Drive Switch Fault, Indicates Neutral During High Load | "B" |
| P1516 | Neutral Drive Switch Fault, Indicates Neutral During Gear Change | "B" |
| P1517 | Neutral Drive Switch Fault, Indicates Drive During Cranking | "B" |
| P1607 | MIL Circuit Open Or Shorted | "A" |
| P1621 | Communication With Security ECM Has Not Happened Within Expected Time | "A" |
| P1622 | 3 Non-Identical Or 2 Identical Wrong Security Codes Received By ECM in Sequence | "A" |
| P1701 | Transfer Case Has Signaled Fault Condition To ECM | "A" |
| P1703 | Transfer Case Link, Signal Line Permanently At Battery Voltage Or Open Circuit | "A" |
| P1708 | Transfer Case Link, Signal Line Permanently at Ground | "A" |
| P1775 | Transmission Has Signaled Fault Condition To ECM | "B" |
| P1776 | Transmission Ignition Retard Request Duration Fault | "B" |
| P1777 | Transmission Ignition Retard Request Line Fault | "B" |
| (1) After each DTC repair has been completed a specific test drive is required to confirm repair. See REPAIR CONFIRMATION TEST DRIVE . (2) Bank "A" is the left side and bank "B" is the right side. (3) Equipped with advanced EVAP system. (4) Recheck using Land Rover TestBook or OBD-II compliant scan tool. | ||
| (1) | After each DTC repair has been completed a specific test drive is required to confirm repair. See REPAIR CONFIRMATION TEST DRIVE . |
| (2) | Bank "A" is the left side and bank "B" is the right side. |
| (3) | Equipped with advanced EVAP system. |
| (4) | Recheck using Land Rover TestBook or OBD-II compliant scan tool. |
DIAGNOSTIC TROUBLE CODE DEFINITIONS
DATA LINK CONNECTOR LOCATION
On all models, Data Link Connector (DLC) is a 16-pin connector. (Scheme 9) DLC is located in passenger footwell. (Scheme 10)
Scheme 9
Scheme 10
ECM CONNECTOR IDENTIFICATION
ECM is located in the right front corner of the engine compartment, next to the battery. Each vehicle has 3 ECM connectors. A Black 36-pin connector, a Red 36-pin connector and a Black 18-pin connector. (Scheme 11)and (Scheme 12). See ECM CONNECTOR IDENTIFICATION table.
| Connector Description | (1) Identification Number |
|---|---|
| Black 36-Pin | C505 |
| Black 18-Pin | C509 |
| Red 36-Pin | C507 |
| (1) See appropriate WIRING DIAGRAMS article. | |
| (1) | See appropriate WIRING DIAGRAMS article. |
ECM CONNECTOR IDENTIFICATION
Scheme 11
Scheme 12
DIAGNOSTIC TESTS
Note. After each DTC repair has been completed a specific test drive is required to confirm repair. See REPAIR CONFIRMATION TEST DRIVE .
REPAIR CONFIRMATION TEST DRIVE
| CAUTION | During repair confirmation test drive it is important to pick a route that is prudent for specified vehicle speeds, and for stop and go driving. Ensure weather and traffic conditions will not impede required conditions of repair confirmation test drive. |
Note. It is important to follow each instruction for each repair confirmation test drive. Failure to perform each instruction under conditions and time period specified may require repeating confirmation test drive. Before turning ignition switch to OFF position at completion of confirmation test drive, recheck for any Diagnostic Trouble Codes (DTCs) using Land Rover TestBook or OBD-II scan tool.
Repair Procedure
Begin all repairs by retrieving Diagnostic Trouble Codes (DTCs) and confirming customer complaint. See RETRIEVING DIAGNOSTIC TROUBLE CODES . Perform appropriate diagnosis and repair. See DIAGNOSTIC TROUBLE CODE DEFINITIONS and appropriate DTC test. After repairs are completed, allow engine to cool and perform specified REPAIR CONFIRMATION TEST DRIVE.
Repair Confirmation Test Drive: "A"
- After completing DTC and complaint repairs allow engine to cool. Install Land Rover TestBook or OBD-II scan tool. Turn ignition on for 30 seconds. Ensure Engine Coolant Temperature (ECT) sensor indicates less than 140°F (60°C).
- Start engine and allow to idle for 2 minutes. Check for DTCs using Land Rover TestBook or OBD-II scan tool. If any DTC is indicated, perform specified repairs. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__diagnostic-trouble-code-definitions) and appropriate DTC testing. If no DTCs are indicated, repair is complete.
Repair Confirmation Test Drive: "B"
- After completing DTC and complaint repairs allow engine to cool. Install Land Rover TestBook or OBD-II scan tool. Turn ignition on for 30 seconds. Ensure Engine Coolant Temperature (ECT) sensor indicates less than 140°F (60°C).
- Start engine and allow to idle for 2 minutes. Perform 2 light accelerations from zero to 35 MPH using light pedal pressure and slow to a stop. Perform 2 medium accelerations from zero to 45 MPH using moderate pedal pressure and slow to a stop. Perform 2 hard accelerations from zero to 55 MPH using heavy pedal pressure and slow to a stop.
- Allow engine to idle for 2 minutes. Check for DTCs using Land Rover TestBook or OBD-II scan tool. If any DTC is indicated, perform specified repairs. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__diagnostic-trouble-code-definitions) and appropriate DTC testing. If no DTCs are indicated, repair is complete.
Repair Confirmation Test Drive: "C"
- After completing DTC and complaint repairs allow engine to cool. Install Land Rover TestBook or OBD-II scan tool. Turn ignition on for 30 seconds. Ensure Engine Coolant Temperature (ECT) sensor indicates less than 140°F (60°C).
- Start engine and allow to idle for 2 minutes. Perform 2 light accelerations from zero to 35 MPH using light pedal pressure and slow to a stop. Perform 2 medium accelerations from zero to 45 MPH using moderate pedal pressure and slow to a stop. Perform 2 hard accelerations from zero to 55 MPH using heavy pedal pressure. When second acceleration cycle is completed, increase vehicle speed to 60 MPH and continue for 5 minutes. Reduce speed to 50 MPH, continue for 5 minutes and slow to a stop.
- Allow engine to idle for 2 minutes. Check for DTCs using Land Rover TestBook or OBD-II scan tool. If any DTC is indicated, perform specified repairs. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__diagnostic-trouble-code-definitions) and appropriate DTC testing. If no DTCs are indicated, repair is complete.
Repair Confirmation Test Drive: "D"
Note. The final phase of Repair Confirmation Test Drive: "D" requires that a flat, straight route be chosen that allows a vehicle speed of 35 MPH to be maintained without stopping or excessive pedal pressure.
- After completing DTC and complaint repairs allow engine to cool. Install Land Rover TestBook or OBD-II scan tool. Turn ignition on for 30 seconds. Ensure Engine Coolant Temperature (ECT) sensor indicates less than 140°F (60°C).
- Start engine and allow to idle for 2 minutes. Perform 2 light accelerations from zero to 35 MPH using light pedal pressure and slow to a stop. Perform 2 medium accelerations from zero to 45 MPH using moderate pedal pressure and slow to a stop. Perform 2 hard accelerations from zero to 55 MPH using heavy pedal pressure. Increase speed to 60 MPH and continue for 5 minutes. Reduce speed to 50 MPH, continue for 5 minutes. Reduce speed to 35 MPH, continue for 5 minutes and slow to a stop.
- Allow engine to idle for 2 minutes. Check for DTCs using Land Rover TestBook or OBD-II scan tool. If any DTC is indicated, perform specified repairs. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__diagnostic-trouble-code-definitions) and appropriate DTC testing. If no DTCs are indicated, repair is complete.
Description
MAF sensor produces an analogue output voltage based on amount of intake air entering engine. Intake air passing through MAF sensor causes heated wire temperature to change. As heated wire temperature changes, resistance also changes causing output voltage to change. ECM measures changes in MAF sensor output voltage and calculates amount of air flowing into engine. ECM uses MAF sensor signal to calculate amount of fuel injected into engine. ECM checks MAF sensor for open circuit and confirms expected sensor output voltage at specific engine speeds.
A default value for airflow can be calculated based on throttle position, engine speed and air temperature. A MAF sensor failure will result in hard engine starts, engine may not idle, poor throttle response and driveability, incorrect emissions, and/or a high long term fuel correction. In addition, engine may start and die when engine speed reaches 550 RPM and ECM does not find a MAF sensor signal.
Diagnostic Aids
- In heavily polluted atmospheres MAF sensor may become contaminated causing incorrect voltage outputs. An air intake system that is restricted, has air leaks or missing components will cause incorrect voltage outputs. Check for poor connections, loose terminals, and open or shorted wires.
- With engine operating at normal operating temperature, check expected output voltage at MAF sensor and at ECM. See appropriate WIRING DIAGRAMS article. (Scheme 11), (Scheme 12) and (Scheme 13). See «MASS AIRFLOW SENSOR OUTPUT VOLTAGE»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l) table. Voltage output should increase as air flow increases. When DTC P0101 repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "B"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-b). When DTC P0102 or P0103 repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "A"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-a).
| Airflow In Lbs/Hr (Kg/Hr) | (1) Output Voltage |
|---|---|
| Minimum | Zero |
| 15.9 (7.2) | 0.8 |
| 23.8 (10.8) | 1.0 |
| 31.7 (14.4) | 1.1 |
| Engine @ Idle (2) | 1.4 |
| 71.4 (32.4) | 1.6 |
| 127.0 (57.6) | 2.0 |
| 222.2 (100.8) | 2.4 |
| 357.1 (162.0) | 2.8 |
| 515.9 (234.0) | 3.1 |
| 714.3 (324.0) | 3.5 |
| 992.1 (450.0) | 3.9 |
| 1349.2 (612.0) | 4.3 |
| 1746.0 (792.0) | 4.7 |
| Maximum | 5.0 |
| (1) Measured between sensor signal at ECM Red 36-pin connector terminals No. 16 (Blue/Green wire) and sensor ground at ECM Red 36-pin connector terminal No. 36 (Red/Black wire). (2) On 4.0L, airflow should be 44.1-52.9 lbs/hr (20.0-24.0 kg/hr). On 4.6L, airflow should be 48.5-57.3 lbs/hr (22.0-26.0 kg/hr). | |
| (1) | Measured between sensor signal at ECM Red 36-pin connector terminals No. 16 (Blue/Green wire) and sensor ground at ECM Red 36-pin connector terminal No. 36 (Red/Black wire). |
| (2) | On 4.0L, airflow should be 44.1-52.9 lbs/hr (20.0-24.0 kg/hr). On 4.6L, airflow should be 48.5-57.3 lbs/hr (22.0-26.0 kg/hr). |
MASS AIRFLOW SENSOR OUTPUT VOLTAGE
Scheme 13
Changes in intake air temperature change IAT sensor resistance. ECM will retard ignition timing when air temperature is more than 131°F (55°C). An IAT sensor fault may result in slight loss of power in high ambient air temperatures.
Check for contaminated sensor, poor connections, loose terminals, and open or shorted wires. See appropriate WIRING DIAGRAMS article. (Scheme 11)and (Scheme 14). Check expected output resistance. See INTAKE AIR TEMPERATURE SENSOR RESISTANCE table. When DTC P0111 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "C". When DTC P0112 or P113 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "A".
| Temperature °F (°C) | Ohms |
|---|---|
| 22 (-30) | 23,000-32,000 |
| 14 (-10) | 8400-10,200 |
| 68 (20) | 2350-2650 |
| 104 (40) | 1000-1300 |
| 140 (60) | 520-670 |
| 176 (80) | 290-365 |
INTAKE AIR TEMPERATURE SENSOR RESISTANCE
Scheme 14
ECT sensor resistance changes as engine coolant temperature changes. ECM monitors ECT sensor resistance values and triggers enrichment circuits to extend injector ON time during cold starting and warm-up (a richer mixture at low coolant temperatures). An ECT sensor failure may result in a fast idle condition on initial start-up until normal operating temperature value is reached. There may be hot engine restart problems.
Check for contaminated sensor, poor connections, loose terminals, and open or shorted wires. See appropriate WIRING DIAGRAMS article. (Scheme 11)and (Scheme 14). Check expected output resistance. See ENGINE COOLANT TEMPERATURE (ECT) SENSOR VALUES table. When DTC P0116-P0118 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "A". When DTC P0125 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "B".
| Temperature: °F (°C) | Resistance (Ohms) | Voltage |
|---|---|---|
| 22 (-30) | 28,000 | 4.70 |
| 14 (-10) | 9000 | 4.20 |
| 68 (20) | 2500 | 2.70 |
| 104 (40) | 1050 | 2.00 |
| 140 (60) | 600 | 1.20 |
| 176 (80) | 330 | 0.75 |
| 266 (130) | 90 | 0.25 |
| (1) Resistance and voltage values are approximate. | ||
| (1) | Resistance and voltage values are approximate. |
ENGINE COOLANT TEMPERATURE (ECT) SENSOR VALUES (1)
DTCS P0121-P0123: THROTTLE POSITION (TP) SENSOR CIRCUIT
Note. On models equipped with Advanced EVAP systems, if DTC P0451 is present, troubleshoot DTC P0451 before TP sensor DTCs. TP sensor and fuel tank pressure sensor share a 5.0 volt reference voltage. A fuel tank pressure sensor failure that causes a short circuit will affect TP sensor output and set a TP sensor DTC.
TP sensor signal informs ECM of actual throttle position and rate of change in throttle position. ECM cross checks TP sensor output with Mass Airflow (MAF) sensor output. If values from these two sensors do not agree and fuel injection feedback indicates correct air/fuel mixture, ECM assumes MAF sensor is correct and TP sensor has failed. A TP sensor failure may result in no idle speed control, poor engine idle and/or poor throttle response.
TP sensor also sends a throttle position signal to Transmission Control Module (TCM). TCM does not seeing a TP signal will cause poor gear change quality, loss of kickdown or TCM to select default transmission control.
Check for contaminated sensor, poor connections, loose terminals, and open or shorted wires. See appropriate WIRING DIAGRAMS article. (Scheme 11), (Scheme 12) and (Scheme 13). Check output voltage. See THROTTLE POSITION SENSOR SIGNAL VOLTAGE table. TP sensor resistance measured between terminals No. 1 and No. 3 should be 3200-4800 ohms. See appropriate WIRING DIAGRAMS article. (Scheme 13) When TP sensor is replaced, closed throttle voltage must be reset. When DTC P0121 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "B". When DTC P0122 or P0123 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "A".
| Position | Volts |
|---|---|
| Minimum | Zero |
| Idle | 0.6 |
| Wide Open Throttle (WOT) | 4.5 |
| Maximum | 5.0 |
THROTTLE POSITION SENSOR SIGNAL VOLTAGE
There are 4 Heated Oxygen Sensors (HO2S) located in the exhaust system. Primary HO2S-1 "A" is located before left side catalytic converter and secondary HO2S-2 "A" is located after left side catalytic converter. Primary HO2S-1 "B" is located before right side catalytic converter and secondary HO2S-2 "B" is located after right side catalytic converter. Secondary HO2S-2 measure oxygen content after catalytic converters to monitor operating efficiency of converters.
Each HO2S is electrically heated to ensure sensor achieves operating temperature as quickly as possible after start-up. ECM energizes HO2S heater using a Pulse Width Modulation (PWM) signal which starts low and increases within 30 seconds to desired heater temperature. Primary HO2S heaters are wired in parallel and secondary HO2S heaters are wired in parallel for synchronous ECM control of each heater pair.
If front HO2S wiring is crossed, vehicle will operate properly until sensors reach operating temperature. ECM will then cause one bank of cylinders to run very rich and the other bank to run very lean. This will cause engine to misfire, idle rough and emit black smoke, with possible catalytic converter damage.
- Indications of HO2S failure may be a strong smell of rotten eggs until default condition is initiated, high CO readings and/or MIL is illuminated. Check for contaminated sensor, poor connections, loose terminals, and open or shorted wires. Ensure wiring to primary sensors is not crossed. See appropriate WIRING DIAGRAMS article. (Scheme 11), (Scheme 12) and (Scheme 15).
- With engine running at normal operating temperature, measure HO2S output voltage between HO2S 4-pin connector terminals No. 1 and 2. (Scheme 15) Output voltage on primary HO2S should change between approximately 0.2 volts (rich mixture) and approximately 4.7 volts (lean mixture). Using a Snap-On Personal Automotive Computer (PAC), compare wave pattern with known-good wave patterns. (Scheme 16) Oxygen content of exhaust gases after catalytic converter should be nearly constant, causing little voltage change in secondary HO2S.
- Measure HO2S heater resistance between sensor connector terminals No. 3 and 4. See appropriate WIRING DIAGRAMS article. (Scheme 15) HO2S heater resistance at 68°F (20°C) should be approximately 5.7 ohms. When HO2S related DTC repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "C"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-c).
Scheme 15
Scheme 16
Engine Fuel Temperature (EFT) sensor is located on the fuel rail and informs ECM when fuel rail temperature is high. Because of fuel vaporization and possible bubbles in the fuel rail, ECM will increase injector pulse width during hot engine restarts to clear bubbles. During engine operation fuel circulation keeps fuel rail temperature low. There is no default strategy for the EFT sensor. An EFT sensor fault may result in a hot engine restart problem. A fault is indicated by illumination of the MIL.
Check for poor connections, loose terminals, and open or shorted wires. See appropriate WIRING DIAGRAMS article. (Scheme 11)and (Scheme 14). Ensure EFT sensor is properly mounted with good thermal contact. Measure EFT sensor resistance between sensor 2-pin connector terminals. (Scheme 14) See ENGINE FUEL TEMPERATURE SENSOR RESISTANCE table. When DTC repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "A".
| Temperature F° (C°) | Ohms |
|---|---|
| 22 (-30) | 23,000-32,000 |
| 14 (-10) | 8400-10,200 |
| 68 (20) | 2350-2650 |
| 104 (40) | 1000-1300 |
| 140 (60) | 520-670 |
| 176 (80) | 290-365 |
ENGINE FUEL TEMPERATURE SENSOR RESISTANCE
Multiport Sequential Fuel Injection (SFI) system uses one fuel injector per cylinder. Fuel injectors are fitted between pressurized fuel rail and intake manifold. Each injector contains a solenoid controlled by ECM. When solenoid is energized, a plunger is pulled off its seat and allows pressurized fuel to spray into the intake manifold. Fuel injector total failure or a leak that causes a rich mixture will cause a misfire in affected cylinder.
Using a stethoscope, listen for clicking sounds from each injector with engine at idle. Check resistance between injector terminals. Injector resistance should be 15.7-16.7 ohms. Check for poor connections, loose terminals, and open or shorted wires. See appropriate WIRING DIAGRAMS article. (Scheme 11)and (Scheme 14). Check for low fuel pressure and/or a blocked, leaking or dripping injector. Using a Snap-On Personal Automotive Computer (PAC), compare wave pattern with known good patterns. (Scheme 17) When fuel injector DTC repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "A".
Scheme 17
DTCS P0300-P0308: MISFIRE DETECTED IN ONE OR MORE CYLINDERS
Note. If DTC P0451 is present, troubleshoot DTC P0451 before misfire DTCs.
ECM has detected a misfire in one or more cylinders. DTC P0300 indicates a random misfire has been detected in more than one cylinder. DTC P0301-P0308 indicates a misfire has been detected in a specific cylinder.
Check for fuel contamination, leaking or blocked fuel injector, faulty spark plugs or wires, faulty coil, low fuel pressure, low cylinder compression, or broken valve spring. When DTC repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "C" .
KS "A" is located on left side of engine block between cylinders No. 3 and No. 5, and KS "B" is located on right side of engine between cylinders No. 2 and No. 4. KS contains a piezoelectric ceramic element which produces a voltage proportional to engine vibration. ECM uses KS, Camshaft Position (CMP) sensor and Crankshaft Position (CKP) sensor signals to verify engine knock based on positions of cylinders. If CMP sensor fails, ECM will suspend knock control.
Check for poor connections, loose terminals, and open or shorted wires. See appropriate WIRING DIAGRAMS article. (Scheme 11), (Scheme 12) and (Scheme 14). Using a Snap-On Personal Automotive Computer (PAC), compare wave pattern with known good patterns. (Scheme 18) When DTC repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "B".
Scheme 18
CKP sensor is located on the left side of flywheel housing and uses a reluctor ring to generate a signal. CKP sensor provides ECM with information indicating that engine is turning, engine speed and crankshaft position during engine cycle. ECM controls fuel injection and coil firing based on signal from CKP sensor. Engine overspeed protection is set at 5500 RPM and is based on CKP sensor signal. There is no default strategy for the CKP sensor. A failure will result in an engine no start condition, misfire, stall and/or poor operation. A sensor fault is indicated by illumination of the MIL.
The reluctor ring has 35 teeth spaced at 10 degrees intervals and one missing tooth. The missing tooth is 20 degrees after cylinder No. 1 TDC. Sensor output amplitude varies with engine speed and sensor gap, output is higher with increased engine speed or smaller gap. Different thicknesses of installation spacers are used for manual or automatic transmissions. If CKP sensor wires are crossed engine timing will be retarded 5 degrees.
Check for poor connections, loose terminals, and open or shorted wires. See appropriate WIRING DIAGRAMS article. (Scheme 12)and (Scheme 14). Ensure CKP sensor pin is not bent, that reluctor ring runs true and that there are no teeth missing. Ensure CKP sensor is correctly mounted and that no water or coolant has entered sensor connector. Sensor resistance should be 1235-1365 ohms. Using a Snap-On Personal Automotive Computer (PAC) tester, compare wave pattern with known good patterns. (Scheme 19) When DTC P0335 and P0336 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "A".
Scheme 19
CMP sensor is a Hall Effect sensor located in the engine front cover. CMP sensor produces 4 pulses for every 2 revolutions of the engine (one pulse is slightly longer than the others). CMP sensor signals are generated from 4 gaps on cam gear (one gap is smaller than the others). CMP sensor signals are used by ECM to correct fuel injector timing for fully sequential operation and for active knock control.
If CMP sensor fails, default strategy is to continue normal ignition timing. Fuel injection timing will default to bank control based on top dead center timing. Injection timing will either be correct or one revolution out of synchronization. Individual cylinder knock control will be disabled and misfire identification may be incorrect. There may not be a driveability problem with a fault being indicated by illumination of the MIL.
Check for poor connections, loose terminals, and open or shorted wires. See appropriate WIRING DIAGRAMS article. (Scheme 11)and (Scheme 20). Unsure CMP sensor is correctly mounted and that sensor connector is clean and tight. Using a Snap-On Personal Automotive Computer (PAC) tester, compare CMP sensor and CKP sensor wave patterns with known good patterns and each other. (Scheme 21) When DTC P0340 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "A".
Scheme 20
Scheme 21
There are 2 Heated Oxygen Sensors (HO2S) mounted at rear of each catalytic converter. The rear HO2S are used to monitor catalyst efficiency.
Visually inspect intake and exhaust systems for damage or leaks. Ensure front HO2S and MAF sensor are operating properly. Check for poor connections, loose terminals, and open or shorted wires. See appropriate WIRING DIAGRAMS article. (Scheme 11), (Scheme 12) and (Scheme 15). When DTC P0420 and P0430 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "C".
DTCS P0441 & P0443: PRE-ADVANCED EVAP SYSTEM MALFUNCTION
Note. DTC P0441 and DTC P0443 apply to the Standard EVAP Loss Control (ELC) system also known as Pre-Advanced EVAP control systems. Refer to underhood emission label for identification of Advanced or Pre-Advanced EVAP system.
Fuel vapor from fuel tank is collected and stored in EVAP control canister that contains activated charcoal. ECM controls release of stored fuel vapor to engine through EVAP control canister purge valve. Stored fuel vapor is purged from EVAP canister to engine and burned during engine operation.
ECM pulses canister purge valve open and closed when engine is at normal operating temperature and engine speed is more than 1700 RPM. ECM monitors HO2S rich/lean signals during EVAP canister purging. A lean signal from HO2S indicates to ECM that EVAP canister is empty. ECM will keep purge valve open during engine operation to ensure canister does not overfill with fuel vapor. A fresh air vent on EVAP canister allows fresh air to enter EVAP canister as engine vacuum draws fuel vapor from EVAP canister.
- ECM monitors EVAP canister purge valve operation for 45 seconds during engine idle, after engine has operated for 15 minutes. ECM controls purge valve operation by providing a modulated ground at ECM Black 36-pin connector terminal No. 19 (Gray/Yellow wire). If EVAP canister purge valve does not operate properly, ECM will store a DTC. There should be no noticeable change in engine operation if there is a malfunction.
- Check for poor connections, loose terminals, and open or shorted wires. Ensure EVAP canister purge valve is not sticky or blocked and that vacuum lines are routed properly and not blocked or leaking. Ensure there are no EVAP system leaks. See pressure testing procedure in appropriate SYSTEM & COMPONENT TESTING article.
- Measure purge valve resistance between purge valve terminals. Purge valve resistance should be approximately 22-40 ohms. Backprobe ECM Black ECM 36-pin connector terminal No. 19 (Gray/Yellow wire) and measure purge valve output signal voltage. During purge valve activation output signal voltage should pulse between approximately 0.0-12.0 volts. See appropriate WIRING DIAGRAMS article. Using a Snap-On Personal Automotive Computer (PAC) tester, compare purge valve wave patterns with known good patterns. (Scheme 22) When DTC P0441 repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "C"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-c). When DTC P0443 repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "A"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-a).
Scheme 22
DTCS P0442, P0446, P1440, P1447, P1448 & P1496: ADVANCED EVAP SYSTEM MALFUNCTION
Note. DTCs P0442, P0446, P1440, P1447, P1448 and P1496 apply to the Advanced EVAP control systems. Refer to underhood emission label for identification of Advanced or Pre-Advanced EVAP system.
Fuel vapor is collected from fuel tank and stored in EVAP control canister that contains activated charcoal. ECM controls release of stored fuel vapor to engine through EVAP control canister purge valve. Stored fuel vapor is purged from EVAP canister to engine and burned during engine operation.
ECM pulses canister purge valve open and closed when engine is at normal operating temperature and engine speed is more than 1700 RPM. ECM monitors HO2S rich/lean signals during EVAP canister purging. A lean signal from HO2S indicates to ECM that EVAP canister is empty. ECM will keep purge valve open during engine operation to ensure canister does not overfill with fuel vapor. ECM controlled EVAP canister vent solenoid valve is located on EVAP canister. Vent solenoid valve allows fresh air to enter EVAP canister as engine vacuum draws fuel vapor from EVAP canister.
Advanced EVAP system includes a fuel tank pressure sensor and an EVAP canister vent solenoid valve, which is normally open. During EVAP system leak testing, ECM closes vent solenoid valve and purge valve. ECM then monitors EVAP system pressure using fuel tank pressure sensor. If ECM detects a pressure decrease greater than a predetermined value, ECM will store a DTC. EVAP system pressure test can detect a system leak as small as 0.04" (1.0 mm). If EVAP canister purge valve does not operate properly or a leak is detected, ECM will store a DTC. There should be no noticeable change in engine operation if there is a malfunction.
- ECM monitors EVAP canister purge valve operation for 45 seconds during engine idle, after engine has operated for 15 minutes. ECM controls purge valve operation by providing a modulated ground at ECM Black 36-pin connector terminal No. 19 (Gray/Yellow wire). If EVAP canister purge valve does not operate properly, ECM will store a DTC.
- Check for poor connections, loose terminals, and open or shorted wires. See appropriate WIRING DIAGRAMS article. Ensure EVAP canister purge and vent solenoid valves are not sticky or blocked. Check that vacuum lines are routed properly and not blocked or leaking. Ensure there are no system leaks. See pressure testing procedure in appropriate SYSTEM & COMPONENT TESTING article.
- Measure purge valve resistance between purge valve terminals. Purge valve resistance should be approximately 22-40 ohms. Backprobe ECM Black ECM 36-pin connector terminal No. 19 (Gray/Yellow wire) and measure purge valve output signal voltage. During purge valve activation output signal voltage should pulse between approximately 0.0-12.0 volts. See appropriate WIRING DIAGRAMS article. Using a Snap-On Personal Automotive Computer (PAC) tester, compare purge valve wave patterns with known good patterns. (Scheme 22)
- When DTC P0442, P1447, P1448 and/or P1496 repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "D"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-d). When DTC P0446 repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "A"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-a). When DTC P1440 repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "C"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-c).
Fuel tank pressure sensor is located on top of fuel tank with fuel pump and fuel gauge sending unit. Fuel tank pressure sensor measures fuel tank pressure allowing ECM to systematically check EVAP system for leaks.
| CAUTION | Before disconnecting any fuel lines or fuel system component electrical connector, clean surrounding area thoroughly. Ensure that there is no fuel system contamination from dust, dirt or other debris. |
Note. Use of any type of contact cleaner, preservative or sealant in an attempt to repair or correct poor electrical connections is not recommended. Use of any of these materials will void manufacturer's warranty.
- Using TestBook or OBD-II compliant scan tool retrieve and record any DTCs. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__retrieving-diagnostic-trouble-codes). Retrieve and record freeze frame data. See «FREEZE FRAME DATA»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__freeze-frame-data).
- Turn ignition off. Backprobe ECM Black 18-pin connector terminal No. 4 (Red wire). (Scheme 12) See appropriate WIRING DIAGRAMS article. Turn ignition on and measure voltage. If voltage is less than 5.0 volts, fuel tank pressure sensor may have a short to ground. Turn ignition off and go to next step.
- Relieve fuel pressure. See «RELIEVING FUEL PRESSURE»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__relieving-fuel-pressure). Disconnect negative battery cable. Lower fuel tank to gain access to 3-pin connector on top of fuel tank. See FUEL PUMP in appropriate REMOVAL, OVERHAUL & INSTALLATION article. Check for poor connections, loose terminals, and open or shorted wires.
- Backprobe ECM Black 18-pin connector terminal No. 4 (Red wire) and measure voltage. Turn ignition on and ensure 5.0 volts exists. Check for continuity in Red/Black wire between fuel tank pressure sensor 3-pin connector terminal No. 2 and ECM Red 36-pin connector terminal No. 36. (Scheme 11)and (Scheme 23). Remove fuel filler cap. Backprobe ECM Red 36-pin connector terminal No. 30 (Green/Pink wire) and ensure 2.84-3.16 volts exists. See appropriate WIRING DIAGRAMS article. Repair as necessary. When DTCs P0451-P0453 repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "A"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-a).
Scheme 23
DTCS P0460-P0461: FUEL LEVEL SENSOR MALFUNCTION
Note. If fuel gauge is not operating properly, fuel gauge must be repaired before proceeding with diagnostics and/or repairs.
Fuel level sensor is located in fuel tank next to fuel pump. It is activated through Body Electric Control Module (BECM) and its sensor signal is also used for fuel gauge display.
- Using TestBook or OBD-II compliant scan tool retrieve and record any DTCs. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__retrieving-diagnostic-trouble-codes) . Retrieve and record freeze frame data. See «FREEZE FRAME DATA»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__freeze-frame-data) . Using TestBook or OBD-II compliant scan tool check fuel level output voltage. Fuel level sensor output voltage specifications are not available from manufacturer.
- On all models, check for poor connections, loose terminals, and open or shorted wires. See appropriate WIRING DIAGRAMS article. Fuel level sensor ground is located at right rear of engine compartment.
- Check for shorts or opens in Green/Black wire between ECM Red 36-pin connector terminal No. 7 and BECM Green 16-pin connector terminal No. 16. Check for shorts or opens in Green/Black wire between BECM Green 20-pin connector terminal No. 10 and fuel level sensor connector terminal No. 1. BECM is located under passenger front seat. See appropriate WIRING DIAGRAMS article. On all models, perform repairs as necessary. When DTC P0460 repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "A"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-a) . When DTC P0461 repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "C"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-c) .
Vehicle speed signal originates at all 4 ABS wheel speed sensors. ABS wheel speed sensors generate an AC voltage signal that is sent to the ABS ECU. The ABS ECU sends a converted signal of 8000 pulses per mile (one pulse about every 8 inches) to the Body Electrical Control Module (BECM). The BECM sends speed signal to the instrument cluster for speedometer operation, to the ECM for engine control and to the air suspension ECU. ECM checks vehicle speed at various engine loads and speeds.
- Check for poor connections, loose wires, and shorts or opens in Yellow/Green wire between ABS ECU Black 35-pin connector terminal No. 28 and BECM Green 20-pin connector terminal No. 11. ABS ECU is located under passenger-side instrument panel. BECM is located under front passenger seat. Repair as necessary. If Yellow/Green wire is okay, go to next step.
- Check for poor connections, loose wires, and shorts or opens in Yellow wire between BECM Green 16-pin connector terminal No. 13 and ECM Red 36-pin connector terminal No. 27. Check for a short in Yellow wire between air suspension ECU Black 35-pin connector terminal No. 30 and splice located in circuit between BECM and ECM. Repair as necessary. If Yellow wire is okay, go to next step.
- Using an oscilloscope, check vehicle speed signal wave pattern between wheel speed sensors and ECM. Ensure there is a consistent signal being transmitted. Repair as necessary. When DTC repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "B"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-b) .
DTCS P0506-P0507 & P1508-P1509: IDLE AIR CONTROL (IAC) VALVE
| CAUTION | During IAC valve diagnosis, IAC valve can be damaged if pintle is manually forced to move. |
Idle Air Control (IAC) valve is used to control engine idle speed. It contains a 2-coil stepper motor and is mounted to throttle housing. When energized in correct sequence, IAC stepper motor coils move a plunger a specified distance or step. Plunger moves a throttle by-pass valve pintle, which increases or decreases idle airflow.
IAC valve fully open position is 200 steps and fully closed position is zero steps. If, during opening or closing, the number of IAC steps recorded changes beyond a specified threshold without a corresponding airflow change Failure of IAC valve will cause low or high idle speed, poor idle, engine stall or engine no start. An IAC valve fault is indicated by illumination of the MIL.
- Ensure there are no vacuum leaks in intake air system and vacuum hoses. Repair and/or replace components as necessary.
- Turn ignition on and off and check for IAC valve motor operation. A vibration should be felt from IAC valve stepper motor when ignition is turned on and a few seconds after ignition is turned off, indicating IAC motor operation. If vibration is not felt, go to next step. If vibration is felt, using TestBook or OBD-II scan tool, ensure IAC stepper motor position at warm idle (engine at normal operating temperature) is 20-30 steps.
- Turn ignition off. Disconnect IAC valve 4-pin connector. Measure resistance of IAC valve motor coils between terminals "A" and "D", and between "B" and "C". See appropriate WIRING DIAGRAMS article. see scheme 16 If resistance is 51-55 ohms, reconnect IAC valve 4-pin connector and go to next step. If resistance is not as specified, replace IAC valve and ensure warm idle position is 20-30 steps.
- Turn ignition off and disconnect ECM Black 36-pin connector. Measure resistance between ECM 36-pin connector terminals No. 15 (Blue/Gray wire) and No. 16 (Red/Green wire) and between terminals No. 34 (Green/White wire) and No. 35 (Orange/Red wire). (Scheme 11) If resistance is 51-55 ohms, go to next step. If resistance is not as specified, check suspect circuits for open or short. Repair circuits as necessary. See appropriate WIRING DIAGRAMS article. When DTC P0506 and P0507 repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "A"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-a). When DTC P1508 and P1509 repairs are completed, verify repairs using TestBook after a full power down.
When ignition is turned to ON position battery voltage is applied to charging system fault indicator. Indicator will go out when generator begins to operate.
Check condition of battery, charging system, and fuses. See appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. When DTC P0560, P0562 and P0563 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "A" .
DTC P0605: ECM DATA CORRUPTED
Manufacture does not provide specific repair information. Check for poor power and ground connections and/or loose wires at ECM connectors. Repair as necessary.
DTCS P1137-P1139: PRIMARY HO2S "A" CIRCUIT MALFUNCTION
DTCS P1157-P1159: PRIMARY HO2S "B" CIRCUIT MALFUNCTION
DTCS P1171-P1172: HO2S TOO LEAN/RICH MALFUNCTION
DTCS P1176-P1177: LONG TERM FUEL TRIM TOO LEAN OR RICH, BANKS 1 & 2 (FUEL MASS FLOW RATE)
Refer to TestBook for specific repair information. When DTC P1178-P1179 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "C" .
DTCS P1178-P1179: LONG TERM FUEL TRIM TOO LEAN OR RICH, BANKS 1 & 2 (AIR MASS FLOW RATE)
Refer to TestBook for specific repair information. When DTC P1178-P1179 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "C" .
DTCS P1185-P1196: HO2S HEATER MALFUNCTION
DTCS P1313-P1315: MISFIRE DETECTED
Refer to TestBook for specific repair information. When DTC P1313-P1315 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "C" .
DTCS P1201-P1208: FUEL INJECTOR CIRCUIT MALFUNCTION
DTC P1316: MISFIRE CAUSING EXCESSIVE EMISSIONS
Refer to TestBook for specific repair information. When DTC P1313 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "A" .
ABS uses all wheel speed sensors to determine if vehicle is on a traveled surface likely to cause a false misfire detection. ECM will disable misfire detection when traveled surface is considered rough enough to create a misfire signal that could set a false DTC.
When ignition is turned on ECM checks rough road signal circuits. If excepted signal is not seen, ECM will store a DTC. Turn ignition off. Connect an oscilloscope positive lead to ECM Red 36-pin connector terminal No. 1 (Yellow/Pink wire) and negative lead to ground. Turn ignition on and observe wave pattern. (Scheme 24) A low to high transition on a rough road indicates a rough road signal which disables the ECM misfire detection. If wave pattern is not as specified, check circuits for an open or short. See appropriate WIRING DIAGRAMS article. Repair as necessary. When DTC P1317 and/or P1318 repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "A".
Scheme 24
Direct Ignition System (DIS) uses 4 double-ended ignition coils located at the rear of the engine. ECM provides internal switching of ground circuit for each coil, which operate on a waste spark principle. A spark is delivered simultaneously to 2 cylinders, one on its compression stroke and the other on its exhaust stroke. Coil No. 1 feeds cylinders No. 1 and 6. Coil No. 2 feeds cylinders No. 5 and 8. Coil No. 3 feeds cylinders No. 4 and 7. Coil No. 4 feeds cylinders No. 2 and 3.
- ECM monitors and performs diagnostics on low tension side of coils. Failure of high tension side of coil will cause misfire DTCs to set. Ignition coil drivers have built-in current limiting and a default action to continue activating coils.
- Turn ignition on and engine off. Check for 12 volts at ignition coil 6-pin connector and at fuse box. See appropriate WIRING DIAGRAMS article. (Scheme 25) If 12 volts does not exist, check for faulty fuse. If fuse is okay, check for an open circuit.
- Check fuse No. 26 (20-amp) in engine compartment fuse box. If fuse is blown, check for continuity between component side of fuse and ground. If continuity exists, repair short in circuit as necessary. See appropriate WIRING DIAGRAMS article.
- Check for poor connections, loose terminals, and open or short in wires between ECM Black 18-pin connector and ignition coils. See appropriate WIRING DIAGRAMS article. (Scheme 12)and (Scheme 25). Repair as necessary.
- Check resistance of each ignition coil. Nominal primary coil resistance should be 0.8 ohms. Nominal secondary coil resistance should be 13,000 ohms. If resistance is not as specified, replace faulty ignition coil.
- Using an oscilloscope, compare ignition coil wave pattern with known good patterns. (Scheme 26) Repair as necessary. When DTC P1361-P1364 and/or P1371-P1374 repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "A"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-a).
Scheme 25
Scheme 26
On vehicles equipped with A/T, ECM uses Park/Neutral switch signal to control engine idle speed. When gear position selector is moved from Park or Neutral position to any drive position ECM will change engine idle speed. When Park/Neutral switch malfunctions, there will be no idle speed change when gear selector is moved from Park or Neutral position to any drive position. Park/Neutral switch is located on left side of transmission. Switch is closed in Park or Neutral position and open in any other position.
- Ensure Park/Neutral switch is not jammed, out of position or improperly adjusted. Check for poor connections, loose wires or an open or short in circuit between Park/Neutral switch and ECM Red 36-pin connector terminal No. 18. See appropriate WIRING DIAGRAMS article. (Scheme 25) Check for poor connections, loose wires or an open or short circuit between ground and Park/Neutral switch. See appropriate WIRING DIAGRAMS article. Repair as necessary.
- Continuity should exist between Park/Neutral switch terminals No. 4 and No. 5 with switch in Park and Neutral positions. Continuity should not exist when switch is in any other position. Replace switch if continuity does not exist in Park and Neutral positions or if continuity exists with switch in any other position. Ensure adjustment and position are correct.
- Turn ignition on. Using a backprobe kit, measure voltage between ground and ECM Red 36-pin connector terminal No. 18. With Park/Neutral switch in drive position, 12 volts should exist. With Park/Neutral switch in Park or Neutral positions, zero volts should exist. Repair as necessary. When DTC repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "B"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-b).
DTC P1607: MALFUNCTION INDICATOR LIGHT (MIL) MALFUNCTION
As a bulb check, Amber CHECK ENGINE MIL will illuminate when ignition switch is turned to ON position and should go out when engine starts. If MIL does not illuminate during bulb check or engine does not start, anti-theft immobilizer system (if equipped) may be activated. If MIL does not illuminate during bulb check and/or DTC P1607 is set, ensure bulb is okay. If bulb is okay check for an open or short in power circuit between fuse and MIL. If power circuit is okay, check for an open or short in control circuit between MIL and ECM. See appropriate WIRING DIAGRAMS article. When DTC repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "A" .
When ignition is turned to ON position (power-up), a coded signal is sent to the ECM to enable the fuel system. When coded signal is received, ECM will perform a MIL (Check Engine) bulb check. If MIL does not illuminate during power-up, vehicle may be immobilized. If the vehicle is fully immobilized, ECM will disable the starter relay and the fuel injectors (preventing vehicle from being hot-wired).
For specific diagnostic and repair procedures, see appropriate ANTI-THEFT SYSTEMS article in ACCESSORIES & EQUIPMENT. When DTC repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "A" .
When transfer gear box Electronic Control Unit (ECU) detects an internal system malfunction, a MIL illumination request is sent to ECM. If transfer gear box cannot move into high range, an incorrect transfer motor position is detected or a vehicle speed sensor malfunction is detected ECM will store a DTC. MIL will illuminate if malfunctions are detected on 2 consecutive trips. Each time the ignition switch is turned to ON position (power-up) the signal line is tested.
Transfer gear box ECU is located under the driver seat. Check continuity of signal line (Blue/Light Green wire) between ECM Red 36-pin connector terminal No. 4 and transfer gear box Black 36-pin connector terminal No. 28. See appropriate WIRING DIAGRAMS article. Repair as necessary. When DTC repairs are completed, perform REPAIR CONFIRMATION TEST DRIVE "A" .
ECM and Transmission Control Module (TCM) are in constant communication. ECM sends throttle angle, engine torque and engine speed signals to the TCM. TCM calculates optimum gear position, signals transmission solenoid valves and sends ECM an engine torque reduction signal. ECM retards ignition timing which reduces engine torque to ensure smooth gear changes.
Engine Speed Signal
ECM calculates engine speed and outputs information to TCM via the Body Electronic Control Module (BECM). The engine speed signal is a 12-volt, square wave pattern with 4 pulses per engine rotation. Engine speed signal is output on Gray wire from ECM Black 36-pin connector terminal No. 23 to BECM Green 16-pin connector terminal No. 9. Engine speed signal continues on Gray wire from BECM Black 20-pin connector terminal No. 11 to TCM Black 55-pin connector terminal No. 3.
Engine Torque Signal
ECM calculates engine torque and outputs this information directly to the TCM. This signal is transmitted as a 12-volt Pulse Width Modulation (PWM). At start-up the engine torque signal includes status on engine warm-up. Engine torque signal is output on Gray/Purple wire from ECM Black 36-pin connector terminal No. 29 to TCM Black 55-pin connector terminal No. 21.
Throttle Angle Signal
A throttle angle signal is calculated by ECM and output directly to the TCM as a 12-volt PWM. If a malfunction occurs with this signal, TCM uses a default throttle angle. Throttle angle signal is output from ECM Black 36-pin connector terminal No. 27 (Yellow/Orange wire) to TCM Black 55-pin connector terminal No. 47 (Orange/Yellow wire).
Engine Torque Reduction/Ignition Retard Signal
TCM calculates an optimum shift point. In order to produce a smooth gear change the TCM sends a torque reduction request signal to ECM. The ECM retards ignition to reduce engine torque and allow for a smooth gear change. Torque reduction/ignition retard request signal is output on Gray/Red wire from TCM Black 55-pin connector terminal No. 32 to ECM Red 36-pin connector terminal No. 31.
- Check for poor connections, loose wires and opens or shorts in wiring harness between ECM, BECM and TCM connectors. See appropriate WIRING DIAGRAMS article. Check for power-up problems. Check for a faulty TCM. See AUTO TRANS DIAGNOSIS article.
- Using an oscilloscope, compare wave patterns with known good patterns. To check engine torque signal, connect oscilloscope to ECM Black 36-pin connector terminal No. 29 (Gray/Purple wire) and battery ground. (Scheme 27)
- To check throttle angle signal, connect oscilloscope to ECM Black 36-pin connector terminal No. 27 (Yellow/Orange wire) and battery ground. (Scheme 28)
- To check ignition retard signal, connect oscilloscope to ECM Red 36-pin connector terminal No. 31 (Gray/Red wire) and battery ground. (Scheme 29)
- To check engine speed signal from BECM, connect oscilloscope to BECM Black 20-pin connector terminal No. 11 (Gray wire) and battery ground. (Scheme 30) Repair as necessary. When DTC repairs are completed, perform «REPAIR CONFIRMATION TEST DRIVE "B"»(/land-rover/range-rover/ii-1994-2002/remont/testing-diagnostics/#engine-controls-self-diagnostics-40l-46l__repair-confirmation-test-drive-b).
Scheme 27
Scheme 28
Scheme 29
Scheme 30
See also:
• RESETTING EMISSION MAINTENANCE REMINDER LIGHT
• DIAGNOSTIC TROUBLE CODE DEFINITIONS
• P0101
• P0121
• P0300
• P0441
• P0442
• P0460
• P0506
• P0605
• P1176
• P1178
• P1313
• P1316
• P1607
• REPAIR CONFIRMATION TEST DRIVE
• RETRIEVING DIAGNOSTIC TROUBLE CODES
• REPAIR CONFIRMATION TEST DRIVE "B"
• REPAIR CONFIRMATION TEST DRIVE "A"
• REPAIR CONFIRMATION TEST DRIVE "C"
• REPAIR CONFIRMATION TEST DRIVE "D"
• FREEZE FRAME DATA
• RELIEVING FUEL PRESSURE