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Dashlights fail

Discussion in 'Rover P6 Electrics' started by Richard B, Oct 14, 2018.

  1. Richard B

    Richard B Member

    Hi All

    My dash lights failed a few days ago. I adjusted the dimmer andvthey came back on for a few mins then failed again. This happened a couple of times and then they failed to work at all. Is this likely to be failure of the dimmer switch? If so are they available at all?


  2. The Rovering Member

    The Rovering Member Well-Known Member

    Remove the wires from the dimmer switch & connect them together. That should tell you either way. l've done this permanently on a couple of cars as l want the dashlights as bright as possible.
  3. Cafcpete

    Cafcpete Active Member

  4. Vern Klukas

    Vern Klukas Active Member

    Most likely the dimmer. I don't know of any source but if you're handy they can be taken apart and cleaned which will help. LEDs are a possibility, but you lose the ability to dim them, unless you're into electronics and can whip up a little adjustable buck regulator.

  5. The Rovering Member

    The Rovering Member Well-Known Member

  6. Phil Robson

    Phil Robson Well-Known Member

    The same thing has just happened to me. The rear lights also failed intermittently - which is a bit more serious!

    Have a look in the fuse box behind the passenger glove box (on a UK Series 2 P6); I'm sure you'll find the relevant fuse (about 1/2 way along & clearly marked on the cover) has slid down over time to the point that its top end is only making occasional contact with the top clip.

    My rear light fuse was the same (as were a few others...) :rolleyes:
  7. Chalky

    Chalky Active Member

    I have leds and they do dim with the dimmer switch. Remember not to put an led bulb in the ignition light as is part of the charging circuit and will not charge with led bulb.
  8. Richard B

    Richard B Member

    First of all thanks for all the comments and time people have taken to read my post - much appreciated.

    UPDATE - today I got behind the dash with a multimeter. The rheostat is definately faulty - infinite resistance between terminals. The fuse is fine... no resistance. The printed circuit board which feeds the bulbs seems to be fine.... no resistance.

    However I don't think the rheostat is the only issue. I bypassed the rheostat and fed wires directly to the dash - still no joy. Checked voltage across feed to the dash and it was zero but the strange bracket from which the feed to the rheostat comes from was getting hot.... is this normal? Or is this shorting out causing no current to the rheostat?

    All a bit of a conundrum at the moment.

    Any hints and tips gratefully recieved.

  9. Richard B

    Richard B Member

    Ok..... I've been a bit thick.

    Just looked at the circuit diagram and the parallel arrangement of the ballast resistor (the bit that gets hot0 and the rheostat.

    Just need to short the terminals on the circuit board to test!
  10. Richard B

    Richard B Member

    Yep that works... das lights came on.

    Rheostat on order
  11. Richard B

    Richard B Member

    so new rheostat installed and failed. eventually found that the lacquer on the printed circuit board was scuffed and the back of the clock was shorting out the circuit.

    repaired lacquer do the nail varnish and installed paper gasket behind clock for good measure.

    connected terminals of rheostat with wire and now have functioning dash lights. although no dim facility. I'll settle for that
  12. ghce

    ghce Well-Known Member

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