Component Tests and General Diagnostics

FAULT DIAGNOSIS

The following tables are intended as a guide to diagnosis of possible faults in the ZF 4 HP 24 E transmission. When the fault involves a leak, it is recommended that it is located by the use of a crack detection fluid, eg. Met-L~heck, which is available in spray form and permits the leak to be located after a short test drive.


Initial Checks

Note: Before attempting fault diagnosis, ensure that the following settings are checked:

Transmission oil level

- Ensure that the transmission is at normal operating temperature, e.g. by conducting a 20 mile road test. If starting from cold: check for presence of oil on dipstick at idle in 'P' Park to the 'Cold' fill mark before setting off.

- Check that the vehicle is on level ground.

- Firmly apply the parking and foot brakes and run the engine at idle speed.

- To ensure that the system is primed, slowly move the selector lever through all the gear positions.

- With the engine still running, engage 'P' Park, withdraw the dipstick and wipe with a lint free cloth.

- Replace the dipstick slowly and withdraw it noting the level.

- Top up as required and recheck the level.

Note: The oil level can only be accurately checked when at normal temperature - approximately 20 miles at moderate speeds.


Selector Cable Adjustment

- Check gear selection in all selector positions.

- If in doubt, select 'N', disconnect the cable at the gearbox selector lever, check that the gearbox lever is in 'N' position (third detent from the rear) and refit the selector cable ball pin to the lever.

- Adjust as necessary at the selector lever inside the vehicle.


Stall Test

- Ensure the transmission is at normal running temperature.

- Fully apply the parking brake.

- Start the engine.

- Fully depress the footbrake.

- Select position 'D'- Drive.

- Fully depress the accelerator('kick~own' switch fully depressed).

- Note the tachometer reading.

- Compare the tachometer reading to the specification.

CAUTION: This test must not last more than 5 seconds. Always allowthe engine to idle for at least 2 minutes between tests to allow the transmission fluid to cool down. Do not carry out more than three tests in any half-hour.

Jaguar Diagnostic Equipment (JDE) must be interrogated and any faults identified and rectified (see JDS Manual / Instructions). Check mode switch and gear selector positions using JDE.


RoadTest

- Fully check all shift speeds and note. Compare the results with the specification in addition to general observations of transmission behaviour, noises, leaks etc., and consult the following Fault Finding Chart.

CAUTION: When renewing the transmission, ALWAYS flush out the oil cooler and feed and return pipes.


Electrical Checks

- Check 'Kick-down'

- If any electrical component fault is suspected, refer to Electrical Diagnostic Manual (EDM~ to verify the failure mode before a repair or replacement is attempted.


Fault Finding Chart





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