XM excessive squatting

[steelcityuk]

Hi all,

In the search for the answer to one or two strange behaviours since putting the SED back on the road I thought that some further investigation was required into the Hydractive system. Unfortunately I can't remember what if any problems the car had before it's layup but I don't remember the nose rising up or rear squatting excessively. Normally I would connect up my Hydractive status light to keep an eye on things and try to find a pattern, however for some reason I resorted to spanners instead. Excessive squatting during acceleration made me suspect that the XM wasn't going into Sports (hard) mode. Two sensors could be the cause of this (I think!), the Accelerator sensor and the Body Movement Sensor, because it happens under gentle acceleration I thought it unlikely to be the Accelerator sensor. The sensor was removed for a clean up and examination, as can be seen one of the contacts is suffering serious oxidation. This was cleaned up using a small file and then cleaned with a cotton bud dipped in switch cleaner, the plug on the XMs loom was dealt with the same way.



I can't find out yet if it's been successful because I've also got the FDV in bits for a service, it has one holed filter and the other is missing all it's mesh.

Steve.

[mongoose100]

Steve, can you please describe to me how to hook a status light up? Trying to do similar but understand that its not 12v.

Ta

[steelcityuk]

Generally speaking you'll need a LED and a 1KOhm resistor, the resistor goes in series with the LED. You then need to tap into the electro valve feed. This could be done at the valve itself but that would mean running cables under the car or tap in in the ECU box under the hood, this is my preference. Next you need to know which wires to tap into, here a circuit diagram helps because of the changes over the years.

On my XM I had a good ideal that the 2 yellow cable were the Electrovalve signal wires so I checked with a couple of pins and a multimeter. First from one yellow wire to negative (GND) and then to Positive on the battery. Then from the other yellow wire. This showed which yellow wire I needed. I tested with the engine off but opened and closed a door before measuring, this give a burst of 12V followed by a lower steady voltage which after around 30 seconds stops as the car goes into hard mode. Remember when using LEDs that they are polarity sensitive so if you connect it the wrong way around the LED won't light even if there is a voltage present.


Test tapping -



I cut down the pin before insulating the tap. The GND wire had a fork type terminal crimped on the end and then clamped under a earthing bolt.


Status LED cable tied to the plastic trim -


With the engine off and all doors shut the LED should be off, after opening a door the LED should blink brightly then should stay dimly lit. If that door is closed (the engine off and all other doors closed) the LED should turn off after around 30 seconds.

Once you've done with the status indicator it would be a good idea to seal up the holes in the wires insulation, a clean followed by a good smear in clear silicon should do the trick.

I expect to see the LED go out when pulling away, accelerating, braking and going over speed bumps. Other conditions will cause the switch into hard mode but these are the ones I'm watching out for.

Steve.