Engine Controls - Self-Diagnostics - with Codes: Diagnosis Land Rover Discovery II

DIAGNOSTIC TESTS (BOSCH)

Note. After each DTC repair has been completed a specific repair confirmation test drive cycle is required to confirm repair. See REPAIR CONFIRMATION DRIVE CYCLE .

DIAGNOSTIC TROUBLE CODES (DTC) LIST

Diagnostic Aids

1. If DTC P0102 is set, MAF sensor signal is less than minimum threshold for specific speed range. Engine speed must be greater than 200 RPM for more than 300 mS and remain greater than 400 RPM. MAF signal must be less than threshold mapped when compared with engine speed for more than 500 mS.
2. If DTC P0103 is set, MAF sensor signal is greater than maximum threshold for specific speed range. Engine speed must be greater than 200 RPM for more than 10 mS. MAF signal must be greater than threshold mapped when compared with engine speed for longer than 300 mS.

Diagnosis & Repair

1. Turn ignition off. Disconnect MAF/IAT sensor unit 5-pin connector. Turn ignition on and measure voltage between ground and connector terminal No. 2 (Brown/Pink wire). (Scheme 8) See appropriate wiring diagram in WIRING DIAGRAMS article. If battery voltage is present, go to next step. If battery voltage is not present, check for an open or short in Brown/Pink wire between MAF/IAT sensor and fuse (No. 2, 15-amp on Discovery Series II or No. 26, 20-amp on Range Rover) located in engine compartment fuse/relay box. Perform repairs as necessary. When repairs are complete, go to step 6.
2. Turn ignition on and measure voltage between ground and MAF/IAT sensor connector terminal No. 4 (Red wire). If 5.0 volts is present, go to next step. If 5.0 volts is not present, check for an open or short in Red wire between MAF/IAT sensor and ECM C0636, 52-pin connector terminal No. 7. Perform repairs as necessary. When repairs are complete, go to step 6.
3. Turn ignition off. Check for continuity between ground and MAF/IAT sensor connector terminal No. 3 (Red/Black wire). If continuity exists, go to next step. If continuity does not exist, check for an open or short in Red/Black wire between MAF/IAT sensor and ECM C0636, 52-pin connector terminal No. 9. Perform repairs as necessary. When repairs are complete, go to step 6.
4. Turn ignition off and connect MAF/IAT sensor 5-pin connector. Start engine and allow to idle at normal operating temperature. Backprobe MAF/IAT sensor 5-pin connector terminal No. 5 (Blue/Green wire) and measure sensor output signal voltage. Output signal voltage should be approximately 0.0-5.0 volts and increase as engine speed and airflow increase. If voltage is as specified, go to next step. If voltage is not as specified, replace MAF sensor and retest. When repairs are complete, go to step 6.
5. Start engine and allow to idle at normal operating temperature. Backprobe ECM 52-pin connector C0636 terminal No. 23 (Blue/Green wire) measure sensor output signal voltage. Output signal voltage should be approximately 0.0-5.0 volts and increase as engine speed and airflow increases. If voltage is as specified, go to next step. If voltage is not as specified, check Blue/Green wire for an open or short between MAF/IAT sensor and ECM. Check for poor connections, loose terminals, and wires. Perform repairs as necessary. When repairs are complete, go to next step.
6. When DTC P0102 or P0103 repairs are completed, perform «REPAIR CONFIRMATION DRIVE CYCLE "A"»(ref-3173-S23415289332000041800000).

Scheme 8

1. If DTC P0111 is set, there is an Intake Air Temperature (IAT) sensor circuit range or performance problem.
2. If DTC P0112 is set, IAT sensor signal is less than minimum threshold, after expected time for exhaust to warm up. The IAT sensor signal will be less than the minimum threshold if the engine has been operating for more than 180 seconds, idle speed control has not been operational for more than 10 seconds, there is no active fuel cut off and the IAT sensor signal indicated is less than -31°F (-35°C) for more than 200 mS.
3. If DTC P0113 is set, IAT sensor signal is more than maximum threshold. The IAT sensor signal will be more than the maximum threshold if the ECM is energized (engine does not need to be operating) and the signal indicated is more than 284°F (140°C) for more than 200 mS.

1. Turn ignition off. Disconnect MAF/IAT sensor unit 5-pin connector. Turn ignition on and measure voltage between ground and connector terminal No. 2 (Brown/Pink wire). (Scheme 8) See appropriate wiring diagram in appropriate wiring diagram in WIRING DIAGRAMS article. If battery voltage is present, go to next step. If battery voltage is not present, check for an open or short in Brown/Pink wire between MAF/IAT sensor and fuse (No. 2, 15-amp on Discovery Series II or No. 26, 20-amp on Range Rover) located in engine compartment fuse/relay box. Perform repairs as necessary. When repairs are complete, go to step 5.
2. Turn ignition off. Check for continuity between ground and MAF/IAT sensor connector terminal No. 3 (Red/Black wire). If continuity exists, go to next step. If continuity does not exist, check for an open or short in Red/Black wire between MAF/IAT sensor and ECM C0636, 52-pin connector terminal No. 9. Perform repairs as necessary. When repairs are complete, go to step 5.
3. Turn ignition off and connect MAF/IAT sensor 5-pin connector. Start engine and allow to idle at normal operating temperature. Backprobe MAF/IAT sensor 5-pin connector terminal No. 1 (Gray/Light Green wire) and measure sensor output signal voltage. Output signal voltage should be approximately 0.0-5.0 volts and will decrease as intake air temperature increases. If voltage is as specified, go to next step. If voltage is not as specified, replace IAT sensor and retest. When repairs are complete, go to step 5.
4. Start engine and allow to idle at normal operating temperature. Backprobe ECM 52-pin connector C0636 terminal No. 34 (Gray/Light Green wire) measure sensor output signal voltage. Output signal voltage should be approximately 0.0-5.0 volts and decrease and intake air temperature increases. If voltage is as specified, go to next step. If voltage is not as specified, check Gray/Light Green wire for an open or short between MAF/IAT sensor and ECM. Check for poor connections, loose terminals, and wires. Perform repairs as necessary. When repairs are complete, go to next step.
5. When DTC P0111, P0112 or P0113 repairs are completed, perform «REPAIR CONFIRMATION DRIVE CYCLE "B"»(ref-3173-S15510008932000041800000).

1. If DTC P0115 is set, there is an Engine Coolant Temperature (ECT) sensor circuit malfunction.
2. If DTC P0116 is set, there is an Engine Coolant Temperature (ECT) circuit/range performance problem. The ECT sensor signal is within limits, but is inaccurate (ECT sensor signal indicates a coolant temperature that is less than 104°F (40°C) and engine is operating). The difference between the ECT sensor signaled temperature and the ECM's expected temperature (based on other sensors) is too much for more than 2.53 seconds.
3. If DTC P0117 is set, there is an Engine Coolant Temperature (ECT) sensor low input signal to ECM. The problem could be an open circuit or short to battery voltage.
4. If DTC P0118 is set, Engine Coolant Temperature (ECT) sensor high input signal to ECM. The problem could be caused by a short circuit to ground.

1. Check for a contaminated sensor, poor connections, loose terminals, and open or shorted wires. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 2, see scheme 3 and (Scheme 9). If no problems are found, go to next step. Perform repairs as necessary. When repairs are complete, go to step 3.
2. Using a thermometer, monitor engine coolant temperature at radiator. Start engine and allow to idle. Backprobe between ECM 52-pin connector C0636 terminals No. 21 (Red/Black wire) and No. 22 (Green wire on Discovery Series II; Green/Blue wire on Range Rover). Compare expected ECT sensor voltage output with monitored engine coolant temperature. See «ENGINE COOLANT TEMPERATURE SENSOR VALUES»(ref-3173-S01833488222000041800000) table. Replace ECT sensor of output voltage does not agree with monitored engine coolant temperature. When repairs are complete go to next step.
3. When DTC P0115-P0118 repairs are completed, perform «REPAIR CONFIRMATION DRIVE CYCLE "B"»(ref-3173-S15510008932000041800000).

ENGINE COOLANT TEMPERATURE SENSOR VALUES

Scheme 9

1. If DTC P0101 is set, there is a mass or volume airflow circuit range or performance problem. DTC P0101 is a load monitoring DTC based on an unexpected throttle position ratio to mass of airflow. DTC P0101 will set if the calculated throttle angle is outside limits when engine speed is between 800-4000 RPM, engine load is between 2.0-6.5 and engine coolant temperature is more than 14°F (-10°C).
2. If DTC P0120 is set, there is TP sensor/pedal position switch "A" circuit malfunction.
3. If DTC P0122 is set, there is TP sensor/pedal position switch "A" circuit low input signal. DTC will set when TP sensor signal is less than minimum threshold when engine speed is more than 400 RPM for longer than 2.0 seconds and the signal is less than 2.0 percent for longer than 50 mS.
4. If DTC P0123 is set, there is TP sensor/pedal position switch "A" circuit high input signal. DTC will set when TP sensor signal is more than maximum threshold value when engine speed is more than 400 RPM for longer than 2.0 seconds and the signal is more than 96.0 percent for longer than 50 mS.

Note. Because ECM is able to determine the closed throttle position, the TP sensor does not need to be adjusted when replaced.

1. Check for poor connections, loose terminals, and open or shorted wires. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 2, see scheme 3 and (Scheme 10). If no problems are found, go to next step. Perform repairs as necessary. When repairs are complete, go to step 3.
2. Turn ignition on. Backprobe between ECM 52-pin connector C0636 terminals No. 24 (Yellow/Light Green wire) and No. 25 (Red/Black wire). Measure voltage while moving throttle valve between fully closed (idle) and fully open (wide open) positions. If voltage is as specified and changes smoothly, go to next step. If voltage is not as specified, replace TP sensor. When repairs are complete, go to next step.
3. When DTC P0101, P0120, P0122 or P0123 repairs are completed, perform «REPAIR CONFIRMATION DRIVE CYCLE "A"»(ref-3173-S23415289332000041800000).

THROTTLE POSITION SENSOR SIGNAL VOLTAGE

Scheme 10

1. If DTC P0130, P0136, P0150 or P0156 is set, there is a circuit malfunction, caused by the stoichiometric ratio of suspect sensor is outside normal operating range.
2. If DTC P0131, P0137, P0151 or P0157 is set, the sensor signal voltage is less than expected, caused by a sensor circuit short to ground.
3. If DTC P0132, P0138, P0152 or P0158 is set, the sensor signal voltage is more than expected, caused by a sensor circuit short to battery voltage.
4. If DTC P0133 or P0153 is set, the front sensor is aged, indicated by a slow responding sensor signal that is either too long or too short.
5. If DTC P0134, P0140, P0154 or P0160 is set, no sensor activity is detected, caused by an open circuit.
6. If DTC P0135, P0141, P0155 or P0161 is set, there is a sensor heater circuit malfunction, caused by an open or short circuit.
7. If DTC P1129 is set, the front sensor connectors have been swapped side to side.
8. If DTC P1170 or P1173 is set, there is a downstream fuel trim malfunction caused by a front sensor that is aged, indicated by a rear HO2S adaptation that is too lean or too rich.

1. Check for contaminated sensor, poor connections, loose terminals, and open or shorted wires. Ensure wiring to front sensors is not crossed. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 2, see scheme 3, (Scheme 11) and (Scheme 12). Perform repairs as necessary. When repairs are completed, go to step 3.
2. Start engine and allow to operate at normal operating temperature. Backprobe specified ECM C0635 connector terminals for suspect HO2S and check signal values. HO2S voltage is difficult to measure using a DVOM, HO2S output can be monitored using a Land Rover TestBook, an OBD-II scan tool or an oscilloscope. A rich mixture should read 500-1000 mV, a lean mixture should read 100-500 mV, and the reading should switch from rich to lean and back. The ECM open loop default voltage is 450 mV, this is used to set the air/fuel ratio until the HO2S reaches operating temperature. Perform repairs as necessary. When repairs are completed, go to next step.
3. When HO2S related DTC repairs are completed, perform specified REPAIR CONFIRMATION DRIVE CYCLE. See DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION (BOSCH) table in SELF-DIAGNOSTICS - INTRODUCTION article.

IDENTIFYING ECM C0635 CONNECTOR HO2S TERMINALS

Scheme 11

Scheme 12

1. If DTC P0170 is set, there is a fuel trim malfunction at Bank 1.
2. If DTC P0171 is set, system is too lean at Bank 1. There is an additive or multiplication injector adaptive fueling malfunction indicated by an exceeded lean limit.
3. If DTCP0172 is set, system is too rich at Bank 1. There is an additive or multiplication injector adaptive fueling malfunction indicated by an exceeded rich limit.
4. If DTC P0173 is set, there is a fuel trim malfunction at Bank 2.
5. If DTC P0174 is set, system is too lean at Bank 2. There is an additive or multiplication injector adaptive fueling malfunction indicated by an exceeded lean limit.
6. If DTC P0175 is set, system too rich at Bank 2. There is an additive or multiplication injector adaptive fueling malfunction indicated by an exceeded rich limit.
7. If DTC P1171 is set, system is too rich at Bank 1. There is an additive injector adaptive fueling malfunction indicated by an exceeded rich limit.
8. If DTC P1172 is set, system is too lean at Bank 1. There is an additive injector adaptive fueling malfunction indicated by an exceeded lean limit.
9. If DTC P1174 is set, system is too rich at Bank 2. There is an additive injector adaptive fueling malfunction indicated by an exceeded rich limit.
10. If DTC P1175 is set, system is too lean at Bank 2. There is an additive injector adaptive fueling malfunction indicated by an exceeded lean limit.

Check for an intake air leak between MAF sensor and throttle body. Ensure fuel pressure is correct. Check for a clogged or leaking fuel injector. Ensure MAF, ECT and HO2S sensors are operating properly. Check exhaust system for leaks. Perform repairs as necessary. When DTC P0170-P0175 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "C" .

If a fuel injector should fail, the following symptoms may be observed

1. Rough running.
2. Difficult starting.
3. Engine misfire.
4. Possible catalyst damage.
5. High emissions.
6. Fueling and idle speed control adaptations disabled.

A fuel injector failure is likely to occur for the following reasons

1. Actuator open circuit.
2. Short circuit to battery voltage or ground.
3. Blocked or restricted fuel injector.
4. Low fuel pressure.

Using a stethoscope, listen for clicking sounds from each injector with engine at idle. Check resistance between injector terminals. Injector resistance should be 13.8-15.2 ohms at 68°F (20°C). Check for poor connections, loose terminals, and open or shorted wires. See WIRING DIAGRAMS article. Check for low fuel pressure and/or a blocked, leaking or dripping injectors. Perform repairs as necessary. When fuel injector DTC repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A" .

If the ECM has detected a misfire in one or more cylinders one of the following DTCs may be set

1. If DTC P0300 is set, a random misfire has been detected in more than one cylinder. MIL will be illuminated.
2. If DTC P0301-P0308 is set, a misfire has been detected in a specific cylinder. MIL will be illuminated.
3. If DTC P1300 is set, a misfire has been detected sufficient to cause catalyst damage on more than one cylinder. MIL will be illuminated.
4. If DTC P1319 is set, a misfire has been detected with a low fuel level in fuel tank. MIL will not be illuminated.
5. If DTC P1301-P1308 is set, a catalyst damaging level of misfire has been detected on specific cylinder.

1. Ensure ECM misfire detection system is properly calibrated for the fluctuations between CKP sensor and the reluctor tooth positions. ECM carries out flywheel and reluctor ring adaptations at various engine speed ranges and can be monitored by TestBook. See «ECM MISFIRE DETECTION ENGINE SPEED»(ref-3173-S17922959262000041800000) table. ECM MISFIRE DETECTION ENGINE SPEED Speed Range Engine Speed 1 1800-3000 RPM 2 3000-3800 RPM 3 3800-4600 RPM 4 4600-5400 RPM
2. Install Land Rover TestBook and monitor ECM misfire detection system calibration and engine speed. Start engine and allow to idle at normal operating temperature. Select 2nd gear and slowly accelerate until engine revolution limiter is activated. Slowly release throttle to allow engine to decelerate through each speed range. Repeat process as necessary until calibration is complete.
3. 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 DRIVE CYCLE "C"»(ref-3173-S07649825702000041800000) .

Noise induced on the battery supply line could be misinterpreted as a knock signal and cause a maximum knock fault. A maximum fault could be caused by a short circuit to the battery supply or in the case of extreme mechanical engine noise/piston slap. A minimum fault is usually due to an open circuit.

A knock sensor failure is likely to occur for the following reasons

1. An open sensor circuit.
2. A short circuit to battery voltage or ground.
3. A malfunctioning KS sensor.
4. An incorrectly installed KS sensor.

When the ECM performs diagnostic checks to confirm correct KS operation the engine must be operating, the engine coolant temperature must be more than 140°F (60°C), and the number of camshaft revolutions since engine start must be more than 50. For a KS DTC to set the KS signal profile must be less than or more than the threshold value at a specific engine speed or the error counter must be greater than the threshold value at a given engine speed.

If a KS should fail, the following DTCs may be set

1. If DTC P0327 is set, the left bank KS signal is less than the threshold value determined by the ECM when engine speed is more than 2200 RPM.
2. If DTC P0328 is set, the left bank KS signal greater than the threshold value determined by the ECM when engine speed is more than 2200 RPM.
3. If DTC P0332 is set, the right bank KS signal is less than the threshold value determined by the ECM when engine speed is more than 2200 RPM.
4. If DTC P0333 is set, the right bank KS signal is greater than the threshold value determined by the ECM when engine speed is more than 2200 RPM.

Check for poor connections, loose terminals, and open or shorted wires. See appropriate wiring diagram in WIRING DIAGRAMS article. When DTC repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "B" .

It is vital that the correct air gap is maintained, if the air gap becomes too wide the CKP signal becomes too weak, causing possible engine misfires to occur. The correct air gap between the tip of CKP sensor and passing reluctor ring teeth is set using the correct spacer. A 0.55" (14 mm) spacer is used on vehicles with M/T and a 0.70" (18 mm) spacer is used on vehicles with A/T. CKP sensor can fail the following ways or supply incorrect signal

1. CKP sensor assembly loose.
2. An incorrect spacer has been installed.
3. There is a sensor open or short circuit.
4. Incorrect sensor installation and integrity.
5. Water contaminated sensor connector.
6. ECM unable to detect software reference point.
7. Sensor pin and/or reluctor ring contamination by ferrous metal or other debris.

Check for poor connections, loose terminals, and open or shorted wires. (Scheme 10) See appropriate wiring diagram in WIRING DIAGRAMS article. Ensure CKP sensor pin is not bent, that reluctor ring runs true and that there are no teeth missing, bent or chipped. Ensure CKP sensor is correctly installed and that no water or coolant has entered sensor connector. Sensor resistance should be approximately 1235-1365 ohms. When DTC P0335 or P0336 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A".

CMP sensor battery voltage is supplied to connector terminal No. 3 (Brown/Pink wire). On Discovery Series II, battery voltage is supplied through the main relay via fuse No. 2 (15-amp) located in engine compartment fuse box. On Range Rover, CMP sensor is supplied with battery voltage through the main relay via fuse No. 26 (20-amp) located in engine compartment fuse box. On all models, ground is supplied to CMP sensor connector terminal No. 1 (Black wire). CMP sensor signal output to ECM 52-pin connector C0636 terminal No. 20 is from CMP sensor connector terminal No. 2 (Gray/Blue wire). (Scheme 13)

CMP sensor can fail or supply an incorrect signal in the following ways

1. An open sensor circuit.
2. Short circuit to battery voltage or ground.
3. Incorrectly installation.
4. Excessive CMP sensor to camshaft gear wheel gap or camshaft end-float.
5. Camshaft and crankshaft misalignment.
6. Speed signal correlation with CKP sensor signal.
7. Camshaft gear wheel magnetized or residual magnetism.

Check for poor connections, loose terminals, and open or shorted wires. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 2, see scheme 3 and (Scheme 13). Unsure CMP sensor is correctly mounted and that sensor connector is clean and tight. When DTC P0340 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A".

Scheme 13

Note. SAI solenoid valve harness 2-pin connector is Gray. Do not confuse with EVAP system purge control valve harness 2-pin connector which is Black.

Battery voltage for SAI air pump operation is supplied from the SAI air pump relay and fusible link No. 2 (50-amp) which are located in the engine compartment fuse/relay box. Operation of SAI pump relay is controlled by ECM through ground circuit. ECM energizes the SAI vacuum solenoid valve at the same time that the SAI air pump is energized. On Discovery Series II, battery voltage for SAI vacuum solenoid valve operation is supplied from Main relay and fuse No. 2 (15-amp) located in the engine compartment fuse/relay box. On Range Rover, battery voltage for SAI vacuum solenoid valve operation is supplied from Main relay and fuse No. 26 (20-amp) located in the engine compartment fuse/relay box. On all models, the ground connection is via the ECM which controls the SAI vacuum solenoid valve operation.

If there a SAI system failure, the following DTCs may be set

1. If DTC P0412 is set, there is a SAI vacuum solenoid valve power supply malfunction caused by a short to battery voltage.
2. If DTC P0413 is set, SAI vacuum solenoid valve is not connected caused by an open circuit.
3. If DTC P0414 is set, there is a SAI vacuum solenoid valve short circuit to ground.
4. If DTC P0418 is set, there is a SAI air pump power supply malfunction. Possible causes are a SAI air pump relay malfunction, SAI air pump or relay not connected, an open circuit or damaged harness.

Scheme 14

Scheme 15

Check for poor connections, loose terminals, and open or shorted wires. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 2, see scheme 3 and (Scheme 16). When DTC P0340 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A".

Scheme 16

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 diagram in WIRING DIAGRAMS article. Check for other DTCs. When DTC P0420 and P0430 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "C" .

Possible symptoms associated with purge valve or associated pipe failure are

1. Engine may stall on return to idle if purge valve is stuck open.
2. Poor idle quality if the purge valve is stuck open.
3. Fueling adaptations forced excessively lean if the EVAP canister is clear and the purge valve is stuck open.
4. Fueling adaptations forced excessively rich if the EVAP canister is saturated and the purge valve is stuck open.
5. Saturation of the EVAP canister if the purge valve is stuck closed.

If the purge valve malfunctions, the following DTCs may be set

1. If DTC P0440 is set, EVAP purge valve not sealing properly.
2. If DTC P0441 is set, an incorrect purge flow has been detected.
3. If DTC P0443 is set, there is an EVAP purge valve short circuit to battery voltage.
4. If DTC P0444 is set, there is an EVAP purge valve open circuit.
5. If DTC P0445 is set, there is an EVAP purge valve short circuit to ground.

Note. EVAP system purge control valve harness 2-pin connector is Black. Do not confuse with SAI solenoid valve harness 2-pin connector is which Gray.

Check for broken or leaking hoses and poor hose connections. Ensure SAI solenoid valve is mounted correctly with directional arrow pointing towards intake air plenum chamber. Check for poor electrical connections, loose terminals, and open or shorted wires. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 2, see scheme 3 and (Scheme 16). When DTC P0440 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "E". When DTC P0443-P0445 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A".

ECM using an in-tank pressure sensor monitors pressure build-up to determine whether leaks are present. Possible reasons for a detected leak are

1. Fuel filler cap is not properly tightened or is missing.
2. There is an in-tank pressure sensor or actuator open circuit.
3. There is a short to battery voltage or ground.
4. Either purge or CVS valve is stuck open.
5. Either purge or CVS valve is stuck closed or there is a blocked line.
6. There is a loose, leaking, broken or disconnected EVAP system line.

If the EVAP system line is broken forward of the purge valve or is not connected, the engine may run rough and fueling adaptations will drift. The malfunction will not be detected by the ECM leak test, but by the ECM detection of a suspended fueling adaptation. The evaluation of EVAP system leakage is dependent on the differential pressure between fuel tank and ambient atmospheric pressure. The leak test is disabled at altitudes greater than 9500 feet.

If ECM detects a EVAP system leak, the following DTCs may be set

1. If DTC P0442 is set, a small leak has been detected within the EVAP system.
2. If DTC P0455 is set, a large leak has been detected within the EVAP system.

Check for poor connections, loose terminals, and open or shorted wires. Ensure EVAP canister purge valve or CVS valve is not sticky or blocked and that EVAP system lines are routed properly and not blocked or leaking. Ensure there are no EVAP system leaks. When DTC P0442 or P0455 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "E" .

The following failure modes are possible

1. Connector or harness wiring open or short circuit.
2. CVS valve stuck open or closed.
3. CVS valve blocked.

If ECM detects a CVS valve malfunction, the following DTCs may be set

1. If DTC P0446 is set, there is a blockage in the CVS valve, filter or line.
2. If DTC P0447 is set, there is a CVS valve open circuit.
3. If DTC P0448 is set, there is a CVS valve circuit shorted to ground.
4. If DTC P0449 is set, there is a CVS valve circuit shorted to battery voltage.

Check for poor connections, loose terminals, and open or shorted wires. Ensure CVS valve is not sticky or blocked and that EVAP system lines are routed properly and not blocked or leaking. When DTC P0446-P0449 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "E" .

Possible fuel tank pressure sensor failures are as follows

1. Damaged or blocked sensor.
2. Wiring harness or connector faulty.
3. Open circuit.
4. Short to battery voltage or ground.
5. ECM malfunction.

If fuel tank pressure sensor should malfunction, the following DTCs may be set

1. If DTC P0450 is set, a EVAP control system pressure sensor malfunction has been detected.
2. If DTC P0451 is set, poor fuel tank pressure sensor performance has been detected, indicated by sensor signal being stuck high within range.
3. If DTC P0452 is set, fuel tank pressure sensor signal is out of range (high) caused by a short to battery voltage.
4. If DTC P0453 is set, fuel tank pressure sensor signal is out of range (low) caused by a short to ground or an open circuit.

Note. Manufacturer does not recommend using any type of contact cleaner, preservative or sealant in an attempt to repair or correct poor electrical connections. Use of any of these materials will void manufacturer's warranty.

Check for poor connections, loose terminals, and open or shorted wires. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 2, see scheme 3 and (Scheme 13). Perform repairs as necessary. When DTC P0450 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "E". When DTC P0451-P0453 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A".

Relieve fuel pressure. See 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 REMOVAL, OVERHAUL & INSTALLATION article. Check for poor connections, loose terminals, and open or shorted wires.

If fuel level sensor should malfunction, the following DTCs may be set

1. If DTC P0460 is set, a fuel level sensor circuit malfunction has been detected.
2. If DTC P0461 is set, the poor fuel level sensor performance or signal out of expected range has been detected.
3. If DTC P0462 is set, the fuel level sensor has a low input signal caused by an open circuit.
4. If DTC P0463 is set, the fuel level sensor has a high input signal caused by a short to battery voltage or to ground.

Note. Fuel level sender signal input is required by ECM as part of the misfire detection strategy if a low fuel situation was present when misfire was detected and logged as a fault. The signal is received as an analogue signal from the fuel tank sender unit.

Check for poor connections, loose terminals, and open or shorted wires. See appropriate wiring diagram in WIRING DIAGRAMS article. Perform repairs as necessary. Check sensor resistance and sensor signal voltage. See FUEL LEVEL SENDER RESISTANCE & SIGNAL VOLTAGE table. When DTC P0460-P0461 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "C" . When DTC P0462-P0463 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A" .

FUEL LEVEL SENDER RESISTANCE & SIGNAL VOLTAGE

If vehicle speed sensor should malfunction, the following DTCs may be set

1. If DTC P0500 is set, there is a vehicle speed sensor malfunction caused by VSS short or open circuit.
2. If DTC P0501 is set, there is a vehicle speed sensor range or performance malfunction indicated by VSS signal that is not within expected range.
3. If DTC P0502 is set, there is a vehicle speed sensor low input signal caused by an open circuit.

On Discovery Series II, VSS input signal from the SLABS ECU is measured at ECM 40-pin connector C0637 terminal No. 22 (Pink/Green wire). VSS input signal is a PWM zero to battery voltage signal. There is a high-line and a low-line bi-directional VSS input signal from the EAT ECU sent using the CAN data bus. The high-line signal from EAT ECU connector terminal No. 16 (White wire) is 2.5-5.0 volts and is measured at ECM 40-pin connector C0637 terminal No. 36 (White wire). The low-line signal from EAT ECU connector terminal No. 44 (Yellow wire) is 0.0-2.5 volts and is measured at ECM 40-pin connector C0637 terminal No. 37 (Yellow wire).

On Range Rover, VSS input signal from the BECM is measured at ECM 40-pin connector C0637 terminal No. 22 (Yellow wire). VSS input signal is a PWM zero to battery voltage signal. There is a high-line and a low-line bi-directional VSS input signal from the EAT ECU sent using the CAN data bus. The high-line signal from EAT ECU connector terminal No. 16 (Yellow/Black wire) is 2.5-5.0 volts and is measured at ECM 40-pin connector C0637 terminal No. 36 (Yellow/Black wire). The low-line signal from EAT ECU connector terminal No. 44 (Yellow/Brown wire) is 0.0-2.5 volts and is measured at ECM 40-pin connector C0637 terminal No. 37 (Yellow/Brown wire).

On all models, if there is a VSS malfunction, ECM applies default values derived from the EAT ECU. Check VSS circuits for opens or shorts and repair as necessary. See appropriate wiring diagram in WIRING DIAGRAMS article. If circuits are okay, replace VSS and recheck. When DTC P0500-P0502 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "B" .

In the event of an IAC valve signal failure any of the following symptoms may be observed

1. Either low or high idle speed.
2. Engine stalls or difficult starting.
3. Idle speed in default condition.

If there is an idle control system should malfunction, the following DTCs may be set

1. If DTC P0505 is set, there is an idle control system malfunction there is a blocked IAC valve indicated by a high or low RPM error.
2. If DTC P1509 or DTC P1510 are set, there is an IAC valve opening coil malfunction caused by an opening winding malfunction.
3. If DTC P1513 or DTC P1514 are set, there is an IAC valve opening coil malfunction caused by an opening winding short to ground.
4. If DTC P1550 or DTC P1551 are set, there is an IAC valve closing coil malfunction caused by a closing winding malfunction.
5. If DTC P1552 or DTC P1553 are set, there is an IAC valve closing coil malfunction caused by a closing winding short to ground.

IAC valve is located on the side of the air inlet pipe on top of the engine. On Discovery Series II, battery voltage for IAC valve solenoid operation is supplied from Main relay and fuse No. 1 (30-amp) located in the engine compartment fuse/relay box to IAC valve 3-pin connector terminal No. 2 (Brown/Orange wire). On Range Rover, battery voltage for IAC valve solenoid operation is supplied from Main relay and fuse No. 37 (30-amp) located in the engine compartment fuse/relay box to IAC valve 3-pin connector terminal No. 2 (Brown/Orange wire). On all models, the ground connections are via the ECM which controls the IAC valve solenoid operation. IAC valve open signal is controlled at ECM 52-pin connector C0636 terminal No. 42 (Blue/Gray wire). IAC valve closed signal is controlled at ECM 52-pin connector C0636 terminal No. 43 (Red/Green wire).

Check for poor connections, loose terminals, and open or shorted wires. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 2, see scheme 3 and (Scheme 10). Perform repairs as necessary. Check IAC valve control voltage. See appropriate wiring diagram in WIRING DIAGRAMS article. When DTC P0505 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "C". When DTC P1509, P1510, P1513, P1514 & P1550-P1553 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A".

If there is a system voltage malfunction, the following DTCs may be set

1. If DTC P0560 is set, there is a system voltage malfunction.
2. If DTC P0561 is set, system voltage unstable.
3. If DTC P0562 is set, system voltage low.
4. If DTC P0563 is set, the system voltage high.

Check condition of battery, charging system, and fuses. When DTC P0560-P0563 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A" .

CAN data bus high-line signal is connected between ECM 40-pin connector C0637 terminal No. 36 (Yellow/Black wire) and EAT ECU 88-pin connector terminal No. 16 (Yellow/Black wire). CAN data bus low-line signal is connected between ECM 40-pin connector C0637 terminal No. 37 (Yellow/Brown wire) and EAT ECU 88-pin connector terminal No. 44 (Yellow/Brown wire). CAN system can fail as a result of an open or short circuit in the CAN data bus wiring.

In the event of a CAN data bus failure any of the following symptoms may be observed

1. MIL will be illuminated after 2 drive cycles.
2. EAT ECU defaults to 3rd gear only.
3. Harsh gearshifts.
4. SPORT and MANUAL indicator lights flash alternately.

If there is a Controller Area Network (CAN) malfunction the following DTCs may be set

1. If DTC P0600 is set, there is a serial communication link malfunction, indicated by CAN time out.
2. If DTC P1776 is set, there is a transmission control system torque interface malfunction EAT torque interface error.

Check for poor connections, loose terminals, and open or shorted wires. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 2, see scheme 3 and (Scheme 17). Perform repairs as necessary. When DTC P0600 and P1776 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A".

Scheme 17

Manufacture does not provide specific repair information. Check for poor power and ground connections and/or loose wires at ECM connectors. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 2and see scheme 3. Perform repairs as necessary. When DTC P0601, P0603 or P0604 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A". When DTC P0606 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "B".

On Discovery Series II, battery voltage is supplied to instrument cluster and MIL from fuse No. 27 (10-amp), located in passenger compartment fuse/relay box. ECM controls MIL operation by providing a MIL ground path at ECM 40-pin connector C0637 terminal No. 20 (Red/Gray wire). Voltage at instrument cluster when MIL is illuminated should be less than 1.8 volts and more than 7.7 volts when MIL is off. Battery voltage is supplied to fuse No. 27 from fusible link No. 8 (50-amp) when ignition switch is in ON position.

On Range Rover, battery voltage is supplied to instrument cluster and MIL from fuse No. 1 (10-amp), located in Body Electrical Control Module (BECM). ECM controls MIL operation by providing a MIL ground path at ECM 40-pin connector C0637 terminal No. 20 (White/Blue wire).

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 P0650 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 diagram in WIRING DIAGRAMS article. When DTC repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A" .

Engine speed signal output signal is a 0.0-5.0 volt PWM sent from ECM 40-pin connector C0637 terminal No. 17 (White/Gray wire on Discovery; Gray wire on Range Rover) to BECM.

Manufacture does not provide specific repair information. Check for poor power and ground connections and/or loose wires at ECM connectors. Perform repairs as necessary. When DTC P0601, P0603 or P0604 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A" .

On Discovery Series II, battery voltage is supplied to fuel pump relay drive circuit when main relay is energized through engine compartment fuse/relay box internal circuits. When fuel pump relay is energized, battery voltage from fuse No. 10 (30-amp) is supplied to fuel pump. Fuel pump relay is energized when ECM provides a ground at ECM 24-pin connector C0635 terminal No. 18 (Blue/Purple wire).

On Range Rover, battery voltage is supplied to fuel pump drive circuit through fuse No. 39 (20-amp) to fuel pump relay and inertia fuel cut-off switch when main relay is energized. Fuel pump relay is energized when ECM provides a ground at ECM 24-pin connector C0635 terminal No. 18 (Blue/Purple wire).

Fuel pump relay can fail the following ways or supply incorrect signal

1. Fuel pump relay drive open circuit.
2. Short circuit to ground.
3. Short circuit to battery voltage.

If there is a fuel pump relay malfunction the following DTCs may be set

1. If DTC P1230 is set, there is a fuel pump relay malfunction caused by a fuel pump relay open circuit and not the fuel pump.
2. If DTC P1231 is set, the fuel pump relay circuit is low caused by a fuel pump relay short to battery voltage and not the fuel pump.
3. If DTC P1232 is set, the fuel pump relay circuit is high caused by a fuel pump relay short to ground and not the fuel pump.

Note. If inertia fuel cut-off switch is tripped, fuel pump will not be energized. On Discovery Series II, inertia switch is located in the engine compartment. On Range Rover, inertia switch is located behind passenger side kick panel. On all models, to reset inertia switch, press down on the rubber top.

Check for poor power and ground connections and/or loose wires at ECM and engine compartment fuse/relay box connectors. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 2and see scheme 3. When DTC P1230-P1232 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A".

If the vacuum operated SAI control valves malfunction (i.e.: from a disconnected or blocked SAI delivery pipe or vacuum hose, etc.) which prevents air delivery to exhaust manifolds, the following DTCs may be set

1. If DTC P1412 is set, there is a SAI system fault on the left side indicated by no air delivery to catalysts.
2. If DTC P1413 is set, there is a SAI system fault on the left side indicated by no air delivery to catalysts.
3. If DTC P1414 is set, there is a SAI system fault on the left side indicated by no air delivery to catalysts.
4. If DTC P1415 is set, there is a SAI system fault on the right side indicated by no air delivery to catalysts.
5. If DTC P1416 is set, there is a SAI system fault on the right side indicated by no air delivery to catalysts.
6. If DTC P1417 is set, there is a SAI system fault on the right side indicated by no air delivery to catalysts.

Check air delivery pipe and vacuum hose connections for leaks or breaks. Ensure air delivery pipes and vacuum hoses are not bent, crushed or blocked. Perform repairs as necessary. When DTC P1412-P1417 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A" .

The A/C request can fail because of the following

1. An open circuit.
2. A short circuit to battery voltage.
3. A short circuit to ground.
4. A wiring harness problem.

The A/C clutch relay can fail because of the following

1. There is an A/C clutch relay open circuit.
2. There is a short circuit to battery voltage.
3. There is a short circuit to ground.
4. There is a broken A/C clutch relay return spring.

If there is an A/C request failure, the following DTC may be set

1. If DTC P1535 is set, there is an A/C compressor request malfunction when A/C operation is first requested when A/C is not in standby mode.

If there is an A/C compressor clutch relay operation malfunction, the following DTCs may be set

1. If DTC P1536 is set, there is an A/C compressor operation request signal range or performance problem caused by a clutch relay open circuit.
2. If DTC P1537 is set, there is an A/C compressor operation request input signal that is too low caused by a short to ground.
3. If DTC P1538 is set, there is an A/C compressor operation request input signal that is too high caused by a short to battery voltage.

Check for poor power and ground connections and/or loose wires at ECM and engine compartment fuse/relay box connectors. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 2and see scheme 3. When DTC P1535-P1538 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A".

The rough road PWM signal can fail in the following ways

1. Harness or connector damage.
2. SLABS wheel speed sensor failure.

If there is a rough road signal malfunction, the following DTCs may be set

1. If DTC P1590 is set, there is an ABS rough road signal circuit malfunction. Hardware is okay, but the SLABS ECU is sending an error signal.
2. If DTC P1591 is set, there is a low ABS rough road signal circuit. Signal from SLABS ECU is shorted to ground.
3. If DTC P1592 is set, there is a high ABS rough road signal circuit. Signal from SLABS ECU shorted circuit to battery voltage.

When ignition is turned on and during vehicle operation ECM checks rough road signal circuits. If expected signal is not seen, ECM will store a DTC. Using an oscilloscope or Snap-On PAC ensure SLABS ECU PWM signal indications are consistent with road conditions. See ROUGH ROAD PWM SIGNAL INDICATIONS table. If PWM signal is not as specified, check circuits for opens or shorts. Check for poor power and ground connections and/or loose wires at ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Ensure ABS wheel speed sensors are operating properly. Repair as necessary. When DTC P1590-P1592 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A" .

ROUGH ROAD PWM SIGNAL INDICATIONS

The HDC signal can fail because of the following

1. Wiring harness or connector damage.

A HDC signal failure may be indicated by the following

1. HDC/ABS warning light illuminated.
2. HDC inoperative and an audible warning.

If there is a HDC signal malfunction the following DTCs may be set

1. If DTC P1663 is set, there is a throttle angle/engine torque signal circuit malfunction caused by an open circuit in the SLABS HDC link.
2. If DTC P1664 is set, there is a throttle angle/engine torque signal circuit low voltage caused by a short circuit to ground in the SLABS HDC link.
3. If DTC P1665 is set, there is a throttle angle/engine torque signal circuit high voltage caused by a short circuit to battery voltage in the SLABS HDC link.

Check for opens or shorts. Check for poor connections and/or loose wires at ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. When DTC P1663-P1665 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A" .

If there is an anti-theft signal circuit malfunction the following DTCs may be set

1. If DTC P1666 is set, there is an engine anti-theft signal circuit malfunction caused by a BCU serial link frame or bit timing error.
2. If DTC P1667 is set, there is an engine anti-theft signal circuit low voltage caused by a serial link short circuit to ground.
3. If DTC P1668 is set, there is an engine anti-theft signal circuit high voltage caused by a serial link open circuit.
4. If DTC P1672 is set, there is an engine anti-theft signal circuit wrong code received with ECM is SECURE state.
5. If DTC P1673 is set, there is an engine anti-theft signal NEW ECM not configured after a NEW ECM has been installed.
6. If DTC P1674 is set, there is an engine anti-theft signal NO CODE ECM, after a valid code has been received from BCU.

A Land Rover TestBook must be used to reconfigure and synchronize the immobilization system. Check circuits for opens or shorts. Check for poor connections and/or loose wires at ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. When DTCs P1666-P1668 and/or DTCs P1672-P1674 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A" .

When cooling fan operation is needed the fan is grounded through ECM 40-pin connector C0637 terminal No. 10 (Black/Pink wire). Battery voltage for cooling fan is provided from fuse No. 26 (20-amp) located in engine compartment fuse/relay box via Brown/Pink wire.

If there is an "E" box cooling fan malfunction the MIL will illuminate and the following DTCs may be set

1. If DTC P1669 is set, the ECM cooling fan circuit malfunction.
2. If DTC P1670 is set, the ECM cooling fan circuit low.
3. If DTC P1671 is set, the ECM cooling fan circuit high.

Ensure "E" box cooling fan is operating properly. Check for opens or shorts. Check for poor connections and/or loose wires at ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. When DTCs P1669-P1671 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A" .

Manufacturer does not provide specific diagnosis and repair information. When DTC P1700 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "B" . When DTC P1701-P1703 and/or P1708 repairs are completed, perform REPAIR CONFIRMATION DRIVE CYCLE "A" .