Engine Controls - Self-Diagnostics - Introduction: Other Land Rover Discovery II

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 INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.

INDICATOR LIGHTS

Note. Malfunction Indicator Light (MIL) cannot be used to retrieve and display Diagnostic Trouble Codes (DTCs).

Note. An incorrectly installed fuel filler cap may cause CHECK ENGINE MIL to illuminate.

Malfunction Indicator Light (MIL)

Discovery Series I models, are equipped with an Amber CHECK ENGINE MIL indicator and an Amber SERVICE ENGINE maintenance reminder light. Discovery Series II and Range Rover models, are equipped with an Amber SERVICE ENGINE SOON MIL indicator. On all models, as a bulb check, MIL indicators 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 indicator 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 INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.

At specified intervals, SERVICE ENGINE or SERVICE ENGINE SOON indicator will illuminate. When indicator 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 .

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.

DISCONNECTING BATTERY

Some Range Rover models are equipped with an anti-theft alarm unit with an internal battery back-up. When ignition is on, the internal battery is charged via an ignition feed. The anti-theft alarm unit will sound for 4.5 minutes if either the unit connector is disconnected or the wires to it are cut. To disconnect main battery, turn ignition on and then off, and disconnect main battery within 17 seconds. Anti-theft alarm will be activated using back-up battery if main battery is not disconnected within 17 seconds. To silence anti-theft alarm if triggered reconnect main battery and turn ignition on. Disconnecting the battery while the alarm system is set will trigger the anti-theft alarm. Always disarm the alarm system before disconnecting the battery. On Range Rover, all handset transmitters must be resynchronized when the vehicle's main battery has been disconnected.

Before disconnecting main 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. With ignition off, position cloth around fitting to catch fuel spray. Using 2 wrenches, loosen fitting. On Discovery Series I and Range Rover, tighten fuel feed fitting to 12 ft. lbs. (16 N.m). On Discovery Series II, tighten fuel feed fitting to 84 INCH lbs. (9.5 N.m).

Discovery Series I

On Discovery Series I, ECM is located in the right rear corner of the engine compartment. The ECM has 3 independent connectors totalling 90 pins. (Scheme 2)and (Scheme 3). See ECM CONNECTOR IDENTIFICATION table.

Scheme 2

Scheme 3

Discovery Series II & Range Rover

On Discovery Series II, ECM is located on the right side "A" post behind the front passenger kick panel. On Range Rover, the ECM is mounted in a plastic "E" box located on the left side of engine compartment firewall. ECM is cooled by a dedicated fan, which provides cabin air to the plastic "E" box maintaining a suitable environment for ECM operation. The operating temperature of the ECM is monitored by an internal temperature sensor. On all models, the ECM has 5 independent connectors totalling 134 pins. (Scheme 4)and (Scheme 5). See ECM CONNECTOR IDENTIFICATION table.

Scheme 4

Scheme 5

ECM CONNECTOR IDENTIFICATION

SUMMARY

If no Diagnostic Trouble Code (DTC) is present but a driveability problem still exists, proceed to 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 is not available from manufacturer.