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    Re: v/w golf oil light on ! Archived Message

    Posted by Shaun Dale on February 2, 2009, 8:18 pm, in reply to "Re: v/w golf oil light on !"

    Hi Ray,
    Most VAG group vehicles have a double pressure switch system. One switch near the pump is a conventional "opens with rise of pressure" switch set at a nominal low pressure. There is also a "close with rise of pressure" switch, often in the head but not always, set to a much higher pressure. this switch is only checked by the instrument cluster above a programmed engine speed. In other words the system looks for a normal minimum pressure at tickover but expects to see a much higher pressure at normal running speed, typically 2500rpm from memory, I think it varies from model to model particularly petrol and diesel. I have had problems with non-gen high pressure switches, they look fine with a test lamp but checked on scope you can see pulses which I think are pressure pulses from the lobes on the pump. The "debounce" on the electronics seems to be inadequate and these pulses will sometimes trigger the alarm. It also looks for the switch to be open at tickover and if it isn't, once again you get the problem,
    I have exactly this problem on a 1990 Audi 80, it makes too much pressure at tickover and brings the light on as result, how can a 20 year old car suddenly make too much pressure? I will post on that one when I get a fix.
    hth, Shaun

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