System Changes and Developments - Pages 8, 9
System Changes and DevelopmentsSince the launch of the XJ6 model range a number of modifications have been incorporated into the Power Hydraulic System. Any significant modifications are detailed in this section.
Modifications
1. From VIN.523301 a revised height sensor (Part NO.DBC 3439) incorporating C.M.O.S. technology was introduced to improve unit reliability and also reduce battery quiescent drain levels. The revised sensor is interchangeable with the previous sensor.
2. From VIN.528301 a modified valve block assembly with increased "trapped line pressure" was introduced to reduce the possibility of "knock" from the rear suspension struts. This valve block is interchangeable with the previous valve block, however, individual solenoid valves are now available from Parts Division. Vehicles prior to this VIN. may be updated by fitting the latest condition down solenoid valve, Part No. CBC 9700.
Note: Strut knock resulting from decayed "trapped line pressure" caused by prolonged non operation of the ride level system, i.e. constantly running the vehicle in a driver only (unladen) condition, is not covered/cured by the above modification.
3. From VIN. 540888 (USA & Canada) and VIN 545153 (R.O.W.), up to 1990 MY, a new brake booster unit (Part NO.JLM 1516) to provide improved braking sensitivity and pedal feedback to the driver was introduced. The new booster is interchangeable with the previous booster unit.
4. From VIN.548307.a revised power hydraulic reservoir (Part No.CBC 6952) incorporating improved sealing around the fluid level switch has been introduced. This will overcome the possibility of fluid leakage. The revised reservoir is interchangeable with the previous reservoir.
5. From VIN 576391, new accumulator charge and low pressure switches were introduced to overcome the possibility of fluid leakage from the switch seals. The new switches incorporate nitrile rubber "quad" seals and are identified by either a pink and a green sleeve or a green sleeve only around the switch cables. The switches are available separately from Parts Division and are interchangeable with the previous switches. Part numbers of the new switches are as follows:
Charge Switch - JLM 1562. Low Pressure Warning Switch - JLM 1563.
6. From VIN.598351 a revised down solenoid valve was incorporated into the valve block assembly. This was to overcome the possibility of "groan" emanating from the valve block when the vehicle was, at rest, following a period of use. The new valve is interchangeable with the previous valve and is available separately from Parts Division under the following part number, CBC 9700.
7. From the 1990 MY introduction the Girling power hydraulic braking system and the Bosch anti-lock system, were replaced by the combined Teves braking system. At the same time a combined H.S.M.O. fluid reservoir was introduced for the ride level and power steering systems.
8. From VIN.598351 an improved unloader valve was incorporated into the valve block assembly. This was to prevent the possibility of extended accumulator charge time or low pressure at idle, caused by unloader valve seat wear. The new unloader valve is interchangeable with the previous one and is available separately under part number, CBC 9701.
9. From VIN.601983 a new power steering/ride level system reservoir was introduced on 1990 MY vehicles. The new reservoir incorporates a revised filler neck and cap, to improve fluid integrity. New features also include improved sealing/bonding of the stub pipes. The new reservoir is interchangeable with the previous 1990 MY reservoir, however, the new filler cap must not be used with an earlier reservoir. Part numbers of the new reservoirs are as follows:
Power Assist/Ride Level Reservoir - CCC 2581. Power Assist Reservoir - CCC 2582.
10. From VIN.617978 a revised ride height sensor incorporating a charge replenishment cycle has been introduced. This prevents decay of "trapped line pressure" during prolonged periods of non operation of the ride level system by charging the system for a few seconds each time the ignition is switched on. The new sensor (Part No. DBC 6170), may be fitted to vehicles after VIN. 594576 provided the vehicle is fitted with PHB high pressure hose Part No. CCC 2625. The PHB hose Part No. is stamped on an aluminium band which is wrapped around the hose.
11. For pre. 1990 MY vehicles (prior to VIN.594576), the following components can be fitted to cure vehicles which suffer from ride level knock due to decay of "trapped line pressure resulting from prolonged periods of non operation of the ride level system. The new sensor (Part No DBC 6170), may be fitted provided:
1. The vehicle is fitted with PHB high pressure hose Part No. CCC2627 (The PHB hose part No. is stamped on an aluminum band which is wrapped around the hose.)
2. The pressure relief valve in the valve block is replaced with the revised one, Part. No. CCC3832 using Service Tool JD 176. Refer to Fig. 8 for ease of identification