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Radiator Fan Issues - Running on ignition - Help

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  • #16
    Originally posted by View Post
    If you pull relays 3 or 11 (in the main fusebox) it should help trace the fault down.
    With both relays out and the fan still runs then you are looking at J135 or J155 misbehaving (or a wiring fault).
    If 3 is out it stops - Had to do that to see if after run pump was working (for 5 secs) on ignition (couldn't hear with fan going), and to use vagcom without the fan running! Ill do some other check tomorrow after work.


    • #17
      Couple of easy things to do then - Relay 3 is Speed 1 (slowest) so its looped into the after-run circuit with J155 etc

      1. Swap relays 3 & 11 over to rule out possibility of relay 3 contacts being mechanically stuck ON
      2. Unplug J155 (after-run relay in the aux panel above driver pedals at position 14 - does that stop the fan running ?
      3. Assuming J155 removal stops the fan operation... plug it back in, then unplug the thermal switch (F98) on the water rail - does that stop the fan operation ?

      I know its tricky getting access to F98, but with care and some luck you should be able to slide one of the two spade terminals off the switch - thats enough to disconnect it. As an alternative, if you know how to extract the relevant pin (temporarily) from T8f then you can do it that way.
      Last edited by; 9th July 2018, 23:05.
      Paul Nugent

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