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I did a diognostics test on my vw eos 2008 dose anyone know what the problem is if the car diognostics is reading the fault to be hydraulic unit
Short circuit to ground or open circuit
Permanent I have no idea what this means and is there a float in the hydraulic pump that cuts off the roof from working if the oil is low
 

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diognostics is reading the fault to be hydraulic unit
Short circuit to ground or open circuit
Diagnostics can sometimes tell one thing when another is the problem. But the text is pretty easy to understand? It may be saying your EOS roof pump is faulty and you have to fit another one? Try that first and tell us if it works? There is plenty of information already here on the EOS roof pump if you search for it, have you tried that?

Roof pump fluid NEVER goes low unless the system is leaking oil somewhere.
 

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Vox,

The Ross-Tech Micro-SCAN does access Module 26 but I cannot determine how comprehensive any fault codes are as it only reports active fault codes and not a complete system status report for the module.
 

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True, but if the roof controller cannot even be read there's another path to go down. Your answer might have been for the other poster with no roof op.? This post is seemingly about a pretty obvious message from a diagnostics scan.

 

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If you can post the fault code number here, you will get more information. :)

Hydraulic unit, short circuit to ground or open circuit sounds like the roof controller can't talk to the pump. I would guess that it's worth checking the wiring on the roof controller and pump, which are common places to suffer in the event of water ingress.
 

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There's no electronic intelligence in the pump, it's just an electric motor with 3 solenoids and a temperature sensor. The roof controller has the H MOS bridge to drive the motor and any 'short circuit' if that message is real, will be a short circuit roof pump or roof controller driving it.

The smart route to determining which, is to disconnect the roof pump at its power plug in the trunk and rescan to see if the same dash warning goes away? If the short circuit error goes away the pump is faulty, if it stays then either the wiring or roof controller is likely to be faulty. QED.
 
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