DS Rev Counter Wiring
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Thread: DS Rev Counter Wiring

  1. #1
    Fellow Frogger! Errol_S's Avatar
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    Default DS Rev Counter Wiring

    The rev counter on my current DS20 rebuild is not working. I have tried fathoming the wiring diagram but am getting nowhere fast - I assume the feed is from the coil.

    Perhaps someone can suggest what can, and should be tested, to try and trace the fault.

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    Regards
    Errol

  2. #2
    Fellow Frogger! Don B. Cilly's Avatar
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    See this.
    It's N 18, and goes from that yellow connector to the coil, yes.
    Hotrodelectric likes this.

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    Now go make me a sandwich Hotrodelectric's Avatar
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    Hi Errol-

    Three-dial car, I'm assuming? There isn't much to it, as Don points out. Just a power and ground supplied directly from the cluster board, and a lone signal wire from the negative side of the coil. More usually the caps in the clockwork fail, leaving you with bad or no function.

    I'm not positive about your car, but for the US cars the signal wire is an overly long one, sheathed in a white vinyl tube, and grouped together with the coil+ and heater fan wires. It's one of only two green wires showing underhood.

    I'm not at home right now, so I can't tell you where it terminates at the cluster connections.
    The measure of your character isn't what you do when people are watching- it's what you do when they aren't watching.

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    Now go make me a sandwich Hotrodelectric's Avatar
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    Quote Originally Posted by Don B. Cilly View Post
    See this.
    It's N 18, and goes from that yellow connector to the coil, yes.
    Just had a look at that Don. That is a very cool find. Nicely spotted.
    The measure of your character isn't what you do when people are watching- it's what you do when they aren't watching.

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    I have had a problem with mine for some time. It has 3 modes - not working at all, working perfectly and showing some revs but quite low. I have checked all the wiring and changed the instrument for another but they both operate the same. I have had one checked by an instrument specialist and it was OK. So the problem must be with the wiring (although I have run a wire direct from the coil to the terminal on the cluster, with no improvement. Any ideas most welcome

    Quote Originally Posted by Errol_S View Post
    The rev counter on my current DS20 rebuild is not working. I have tried fathoming the wiring diagram but am getting nowhere fast - I assume the feed is from the coil.

    Perhaps someone can suggest what can, and should be tested, to try and trace the fault.

    Regards
    Errol
    Citroen DS21 Pallas 1970 Renault 16TS 1976 Renault 5TS 1981

  6. #6
    Fellow Frogger! Don B. Cilly's Avatar
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    Quote Originally Posted by tresbon2 View Post
    It has 3 modes - not working at all, working perfectly and showing some revs but quite low.
    Mine only has the first two. It depends on temperature. It only works above, roughly, 12C.
    So on cold days, it won't work in the morning, then it warms up and it does.
    They tell me it depends on the plexiglas touching the central hub. We don't get many days in the year when it's that cold, so I don't really worry about it.

    If yours looks temperature related too, then it could be the same thing...

    Quote Originally Posted by Hotrodelectric View Post
    That is a very cool find.
    Uh, I've had that for ages, it's from dssmpassion (quite a little gold mine of a site), I'm surprised you didn't have it.

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    Fellow Frogger! Errol_S's Avatar
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    Thank for the feedback.

    I have tested the feed from the -ve side of the coil and that is in accordance with Don's template (18). The earth at point 19 is also in order. Both of these connections feed correctly to the back of the gauge. By rotating the cluster the rev counter needle appears to move freely. Looks like I will have to find a donor gauge.

    Regards

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    Fellow Frogger! badabec's Avatar
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    Hello, if you are at the 'nothing to lose' stage, have you considered removing the tacho and putting it a bath of isopropyl alcohol (not the 70% stuff, the 100% stuff), swilling it about a bit then draining and allowing to dry in a warm place?

    Don't use acetone, it will melt the dial.

  9. #9
    Now go make me a sandwich Hotrodelectric's Avatar
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    Quote Originally Posted by tresbon2 View Post
    I have had a problem with mine for some time. It has 3 modes - not working at all, working perfectly and showing some revs but quite low. I have checked all the wiring and changed the instrument for another but they both operate the same. I have had one checked by an instrument specialist and it was OK. So the problem must be with the wiring (although I have run a wire direct from the coil to the terminal on the cluster, with no improvement. Any ideas most welcome
    If that's case- you've run a seperate wire- you've pretty well proven it isn't the wiring. Question: are all of your other warning lamps and the fuel gauge working? If not, it isn't the tach, since your entire cluster takes power from a fuse- green one in the main box, I think, through the ignition switch, and then split to ignition fed circuits, i.e.the cluster.

    Something of a trick you may want to try if the power feed is good: take the cluster apart, down to the board, and clean all contact surfaces with a plain pencil-end eraser. You don't need to make the entire set of traces shiny, just where the components connect. For the wire connections, just plug and unplug a few times.

    Quote Originally Posted by Don B. Cilly View Post

    Uh, I've had that for ages, it's from dssmpassion (quite a little gold mine of a site), I'm surprised you didn't have it.
    No, I hadn't. I have a list of Citroen bookmarks longer than you are tall, just goes to prove I don't have 'em all.
    The measure of your character isn't what you do when people are watching- it's what you do when they aren't watching.

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