With LH System Tester

LH System Tester





The test equipment consists of an instrument, a power supply cable, a test cable with a double connector and a pressure sensor with magnet.

The test cable is available in two versions:
25-pin, for cars with LH 2.2
35-pin, for cars with LH 2.4, LH 2.4.1 and LH 2.4.2


Power supply
The cable with battery terminal clamps connects to the battery to provide the +12 V power supply.


Pressure sensor
The pressure sensor connects to the LH system for fuel pressure measurement.
Range of measurement: 0-10 bar
Pressure class: 1%


Connection to the car
Connection is made between the control module and the car's wiring harness by means of a double connector (male/female type) and a 2-metre exchangeable cable.

1 Access the control module by removing the cover panel over the false bulkhead space on the left-hand side.
If the car is equipped with ABS brakes, unplug the ABS control module and remove its bracket. Remove the control module retaining screws.

2 Connect the instrument by plugging in the cable with the double connector to the control module and the car's wiring harness.
Use the 25-pin connector on cars with LH 2.2 and the 35-pin connector on cars with LH 2.4, LH 2.4.1 and LH 2.4.2.

3 To avoid nipping, run the cables between door and body where the weather seal is separated and then under the trailing edge of the bonnet on the left-hand side.

Connect the clamps to the battery, first negative (-) and then positive (+).

Important: Check that the battery terminal posts are clean so that good contact is assured. Always make sure that the power supply cable is connected to the instrument before connecting it to the battery.


Before starting work
Before starting fault diagnosis with the LH tester, it is advisable to use the integral fault diagnosis system on cars with LH 2.4 to check that no intermittent faults are stored in the LH control module.

It is important to do this first, because connecting the LH tester to the system cuts off the control module's power supply with the result that its fault memory is cleared and the possibility of detecting intermittent faults is lost.

The same applies when either of the battery cables is disconnected.

In a computerized fault diagnosis system like the LH system tester, reference values for some of the parameters to be checked are preprogrammed in the tester's memory.

The reference level in the software must be balanced in such a way that any existing faults will be detected, in certain cases within extremely tight limits. This means that in such cases a fault may sometimes be indicated when in actual fact no fault exists.

This can only happen in situations where driving conditions are vastly different from those normally encountered.

Examples of spurious faults that may be indicated under these conditions are as follows:

LH 2.2 LH 2.4

E0020 E013 Excessive warm-up period, due to a faulty thermostat or prolonged idling in extremely cold weather.

E020 E020 Prolonged engine braking, incorrect signal level from the oxygen sensor.

E207 E207 Prolonged acceleration at wide open throttle; abnormally high mass air flow sensor voltage.

E113 E118 Engine overrevved, over revcut-out tripped, boost pressure too high.

It often happens that the fuel injection system is suspected of being faulty when the fault really exists in the engine itself or the electrical system.

Therefore, check the following points before testing the fuel injection system:
- Battery condition
- Charging system
- Ignition system (timing, spark plugs, HT leads, distributor cap, rotor, etc.)
- Battery connections and grounding point
- Engine condition (compression, intake manifold vacuum, etc.)
- Air leakage in turbo-induction system

In some cases a quick check of the main relay and pump relay can be carried out to advantage, as follows:

1 Unplug the connectors from the LH control module and mass air flow sensor.

2 Plug in a Breakout Box (BOB).

3 LH 2.2
Connect pins 17 and 21 to ground via pin 25.
LH 2.4
Connect pins 20 and 21 to ground via pin 17

4 Check that power is supplied to:
LH 2.2 on:
pins 9 and 13 (LH control module)
pin 2 or 5 (mass air flow sensor)
pin 2 (IAC valve)
fuse 14 (fuel pump relay)
LH 2.4 on:
pins 9 and 18 (LH control module)
pin 5 (mass air flow sensor)
fuse 14 (fuel pump relay)