Oil Pressure Gauge - Low/Inaccurate Readings
DATE 6/9515-13
MODEL
1995 MY
Sedan Range
VIN
720001-746613
Oil Pressure Gauge - Fluctuation or Low Pressure Readings - Modification Procedure
ISSUE:
The use of thinner, energy saving engine oil can cause lower oil pressure. As a result, on some vehicles the oil pressure gauge needle may fluctuate or read low or zero during normal operating conditions.
On V12 engines, oil pressure may be as low as 7 psi (0.5 bar) at idle which is still acceptable. However, the current low oil pressure warning system cannot always distinguish between this and the lower oil pressures that signify an actual fault.
As a result the system can give inaccurate readings with needle fluctuations or a zero reading.
On AJ16 engines, the currently used oil pressure sensor gives inaccurate readings by showing either a zero reading on the gauge or producing needle fluctuations.
ACTION:
In the event of a customer complaint only, install a new oil pressure switch in place of the sensor and reprogram the instrument pack as follows:
NOTE:
This modification converts the oil pressure gauge into a simple on/off indicator. The gauge will read mid-scale at all normal driving conditions.
The needle will only deflect from mid-scale to zero if a low oil pressure condition occurs. At the same time, the oil pressure warning indicator will also illuminate.
It is important that the customer understands the effect of this modification.
1. Disconnect the battery ground lead.
2. Disconnect the wiring harness from the oil pressure sensor.
3. Unscrew and remove the oil pressure sensor.
4. Screw the new switch in by one thread. Apply Loctite 542 thread sealer to the exposed threads and torque to 8 - 9.5 lb.ft (11 - 13 Nm).
5. Reconnect the wiring harness to the switch.
6. Reconnect the battery ground lead.
7. Reset the clock.
8. Load the PDU Service Action Disc, Version 1.
9. Enter the VIN as requested. If the VIN is outside the range of 720001-746613, the software will return the user to the VIN screen to indicate an unacceptable VIN entry.
10. The software will indicate to connect the Vehicle Battery Adapter. The next screen will state: "This software will give instructions to replace the oil pressure transducer on a vehicle with a switch and then program the instrument pack accordingly". After these instructions the PDU will ask if the user wishes to continue with the programming; (At this point, the sensor should have been replaced by the pressure switch.)
11. Connect the PDU to the vehicle using the serial comm. cable and the VBA as instructed.
12. Switch the ignition ON.
13. The PDU will then establish communications with the instrument pack.
14. The PDU displays the message "Please wait" while it reads the software version from the pack along with the calibration values.
15. If the calibration is correct, no reprogramming is required. If incorrect, the PDU disables the gauges and writes new values, then reactivates the gauges.
16. The PDU will display a message to indicate if the reprogramming was successful. The PDU then returns to the VIN screen.
PARTS INFORMATION:
DESCRIPTION PART NUMBER
Oil pressure switch LNA 5642CA
NOTE:
This switch is installed in production from the following engine serial numbers onward:
6 cyl. Serial Number 9J134020
V12 Serial Number 8E11876
WARRANTY INFORMATION:
Labor time includes the time to reprogram the instrument pack.
PARTS INFORMATION:
DESCRIPTION PART NUMBER
Dimmer Module LXF 6940AA
WARRANTY INFORMATION: