Jaguar XJS Oil Pressure Switch: Common Problems and the Usual Causes
The oil pressure switch is like a fire alarm in your house. Just as the fire alarm sounds off when it senses smoke, the oil pressure switch turns on the warning light of your dashboard when the oil pressure is low. This will let you avoid a possibly catastrophic engine failure. You may get false warnings once in a while, but it's forgivable, given its very important job. When the false alarms become much more frequent, you'll need to have the unit checked right away. Here's how you can diagnose such problems associated with the Jaguar XJS oil pressure switch:
Oil pressure warning light switches on and off
When the oil pressure warning light first switches on, the first thing you must always do is to check the oil level of the Jaguar. If the reading on the Jaguar's dipstick shows that the oil level is between the minimum and maximum level, then you should check the oil pressure switch next. Disconnect the oil switch and check the oil gauge. If the warning light disappears, then it means that your oil switch is bad and needs to be replaced. If warning light is still on, there might be a problem with the electrical circuit of the oil pressure warning light.
Oil pressure light switches on when idle
If the XJS is idling, it is natural for the oil pressure in the engine to be low. Oil pressure switches are supposed to take that into account and prevent themselves from switching on the warning lights during idling. As always, once the light comes on, be sure to check the oil pressure of your Jaguar first. If the oil level is okay, try testing the switch with an ohmmeter. Test the switch with the Jaguar's engine off and do it again with the engine on; record both readings. The difference of both readings should be at least 500 ohms; any less means that there is a problem with the oil switch.
Other troubleshooting tips
Always assume the worse. When your oil warning light switches on, always assume that both your oil pressure and oil level is low. Check the oil level first before you try troubleshooting the oil pressure switch.
Some Important Maintenance Issues with Jaguar XJS Oil Pressure Switch
Driving without a working oil pressure switch is a big mistake for anyone. Without it, there would be no way for you to know if the oil level in your engine is dangerously low. The only time you'd realize the imminent catastrophe your Jaguar's engine is getting in is when you start to hear the telltale knocking sound inside the engine; by this time though, it would already be too late. What follows is a repair bill reaching upwards to thousands of dollars. To prevent such a tragedy from happening, always keep the switch working properly. For more information regarding the Jaguar XJS Oil pressure switch maintenance, keep reading.
Inspect the oil pressure switch and its wires for any damage.
An inspection of the oil pressure switch could tell you the current state it is in. Remove the pressure switch from within the engine compartment and inspect it for any damage. Take a look at the wires as well; be sure that none are damaged or broken.
Check the oil level of the Jaguar's engine and test the oil switch's performance whenever the oil pressure warning light flickers.
If the oil pressure switch is functioning normally, the oil warning light will turn on when the oil pressure is low and will remain so until the issue is fixed. If the light starts to flicker, the sensor might be malfunctioning. Even then, check the oil level of the Jaguar immediately to determine if the car has enough oil inside the engine. If the oil level checks out, then you can test oil switch with an ohmmeter. Measure the readings of the switch with the engine off and then once more with the engine running; the readings of a working sensor should have a difference of about 500 ohms.
Replace a malfunctioning oil pressure switch with a new one as soon as possible.
If the old oil pressure switch has malfunctioned and if repairing the unit is out of the question, have the whole thing replaced instead. Oil switch repairs are somewhat uncommon and, given the relatively affordable price of the part, replacing the whole thing has become the solution of choice. Be sure to replace the unit as soon as possible. Without anything to warn you about possible problems with the oil pressure, you could find yourself driving a Jaguar with barely enough oil in it and you wouldn't even know about it.