With LH System Tester
LH multiport fuel injection system test unit
The test equipment consists of an instrument unit, a cable for power supply, a measuring cable with a double connector and a pressure sensor with magnetic fastening.
There are two designs of measuring cable:
• 25-pin for cars with LH 2.2
• 35-pin for cars with LH 2.4
Power supply
Connect +12V with battery clips to the battery.
Pressure sensor
Connect the pressure sensor to the LH MFI system to measure the fuel pressure.
Measuring range: 0-10 bar
Pressure class: 1%
Connection to car
The connection is made between the engine control module (ECM) and the car's wiring system with a double connector (male and female design) and a 2 metre long replaceable cable.
1 Uncover the ECM by removing the cover-plate over the torpedo space on the left-hand side.
If the car is equipped with ABS brakes, loosen the ABS control module and its bracket.
Remove the ECM's securing screws.
2 Connect the instrument by connecting the cable with the double connector between the ECM and the car's wiring system.
For cars with LH 2.2 use a 25-pin connector and tor cars with LH 2.4 a 35-pin connector.
3 In order to avoid damage caused by crushing, lay the cables between the door and the chassis where the sealing strip divides and then continue below the rear end of the hood on the left- hand side.
Connect the clips to the battery; first negative (-) then positive (+).
Note: Check that the battery terminals have been cleaned in order to achieve a good contact. Ensure that the power supply cable is connected to the instrument before you connect it to the battery.
Before you start work
Note:
- Before starting to trace faults with the LH tester it is advisable to check first, via the built-in fault- diagnosis system, that there are no intermittent faults stored in the LH engine control module (ECM).
- When the LH test unit is connected to the system, the power supply to the ECM is cut off, resulting in the ECM's fault memory being cleared and the possibility of directly detecting intermittent faults thus disappearing.
- This also applies if any of the battery cables are disconnected.
It sometimes happens that there is a suspicion that the injection system is faulty, when the real fault is in the engine itself or in the electrical system. Thus check the following points before you test the injection system:
- Battery condition
- Charging system
- Ignition system (setting, spark plugs, cables, distributor cap, rotor etc).
- Battery connections and grounding point.
- Engine condition (compression, vacuum in inlet pipes etc).
- Air leakage in turbo/inlet systems.
In certain cases it could be advantageous to carry out a quick check of the main relay and the pump relay as follows:
1 Release the connectors from the LH ECM and the mass air flow sensor.
2 Remove the cover-plate on the connector to the LH ECM.
3 LH 2.2:
Ground pins 17 and 21 to pin 25.
LH 2.4:
Ground pins 20 and 21 to pin 17.
4 Check that there is power for:
LH 2.2 on:
pins 9 and 13 (LH ECM)
pin 2 (IAC valve) or, alternatively, pin 5 (mass air flow sensor)
fuse 30 (fuel pump relay)
LH 2.4 on:
pins 9 and 18 (LH ECM)
pin 5 (mass air flow sensor)
fuse 30 (fuel pump relay)
Note: In a computer-based fault-tracing system like the LH MFI system test unit, programmed values are used as reference for certain parameters which are to be checked.
The reference level in the software must be balanced to a level where faults can be detected, in certain cases within very tight limits. This means that in these cases fault- indication can sometimes occur, even if there is no fault.
This can only happen in connection with operational situations which deviate considerably from normal driving conditions;
Examples of faults which could be detected under these conditions are:
LH 2.2 LH 2.4
E002 E013 Warms up too slowly, for example faulty thermostat or long period of idling in very cold conditions.
E020 E020 Using the engine for braking for a long period, signal level from heated oxygen sensor faulty.
E207 E207 Full throttle acceleration for a long period; mass air flow sensor voltage abnormally high.
E113 E118 Engine speed limit exceeded; over-reving protector released, charging pressure too high.