Hello again everyone, I've got some new confusing issues for you all. My 1988 Vanden Plas is displaying a new error, "Power Fluid Low" I cannot find online what it is referring to by this, but I tried checking the hydraulic fluid, it was slightly low, so I rectified that. However the fault did not go away. The next thing I did was head online to try to figure out what was going on, and I found a Jaguar Tech publication on the hydraulic system. I found that my car has, at some point in it's life, been retrofitted with the 1990 Hydraulic reservoir instead of the 1988 proper unit with the gauge built in. It also has an independent power steering fluid reservoir which takes plain jane red Dexron power steering fluid. I suppose the long and the short of my questions is, what is the purpose of retrofitting the later hydraulic arrangement, and what can the "Power Fluid Low" warning refer to? I've searched here, I've searched Jag-lovers, and I've searched XJ40, and I can find nothing helpful.

Thank you for your time, Evan.

 

Now that I've been under the hood with the car running I have been able to narrow it down to the accumulator charge switch causing the surging which I'd imagine could cause a low pressure error. Does this seem right to you folks?

 

The original green HSMO reservoir was a leak prone POS.
The level sensor wire seal/grommet leaks fluid on EVERY one I ever saw.
The reservoirs are probably NLA so people find different ways to keep these cars going.

Be glad someone already found a solution to keep fluid in a reservoir instead of leaking on the ground.
I have one customer left with a 1988 XJ sedan and they just bought a replacement reservoir online. I installed it and it leaks just as bad as the one it replaced.

I suggested finding a 1990 onward reservoir and retrofit it. Seems like you already have that option.

Make sure the SLS sensor on the right rear lower arm is UNPLUGGED if the SLS has been deleted. The valve will try to send fluid to the SLS dampers to lift the rear suspension, but if they are not fitted, the valve block overpressures and a constant 'thump,'thump,'thump,'thump,'thump,'thump,' with a visible swelling of the high pressure hose occurs as the relief valve operates.

bob