New guy with DS21 doubts on pilot lights
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Thread: New guy with DS21 doubts on pilot lights

  1. #1
    Tadpole
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    Default New guy with DS21 doubts on pilot lights

    Hi guys:

    First post to the forum. I live in Mexico, collect old cars and among several of them I have a 1970 DS21, two SM (one of them in need of cosmetics) and one 2CV Camionette project. I have to say I understand only the very basics of mechanics in general but I do have a friend who helps me maintain them.

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    My DS21 is basically a very good car. Originally a US spec car which was converted by the prior owner to "european looks". I bought it from a Citroen collector and the car almost works great. The "almost" is basically for a couple of things that I need to correct.

    1. Pilot lights, the three important ones: The oil pressure light works well and lights up the STOP big light in the middle. Same I guess is true with the temperature light, which lights up when pressing the dashboard button but luckily I have never had a temperature problem to see if it lights up when hot. My problem is the hydraulic system light. It does light up with the ignition switch on, but as soon as the car's engine starts, it goes off, together with the rest of the lights. and I believe the hydraulic system light should still be on, together with the STOP light, so you remember you cannot move the car while the suspension has not filled itself and the car has come to it's usable ride height. How can I check on it and get it back to work?

    2. Parking brake light. I am guessing one of the lgihts should be for the parking brake, as it shows a brake pedal, but my car never lights it up. I have gone over the the emergency brake to see if I can find a switch to operate it, but I haven't, at least not inside the car. Am I correct in guessing there should be a switch and a pilot light for that? I can't tell you how many times I have driven the car with the emergency brake partly enganged!

    A few more doubts on the car but I will start off with these.

    Thanks for any help,
    Victor
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  2. #2
    Tadpole
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    By the way... this is the car:

    New guy with DS21 doubts on pilot lights-1970-citroen-ds21.jpg

  3. #3
    Fellow Frogger! citroenthusiast's Avatar
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    The picture of the pedal is actually your front brake pad wear indicator light. The parking brake does not have a pilot light. You must remember yourself to release it.
    Cheers,
    John T.

    54 TAV Legere; 61DS19 LHM BVH (son's); 71DS21 BVH; 73SM 3.0; 73SM EFI (Megasquirt); 73SM 3.0 (other son's)

  4. #4
    Fellow Frogger! citroenthusiast's Avatar
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    The hydraulic system pressure indicator wire should be attached to a pressure switch located on the priority/security valve. The priority/security valve is located under the left front suspension cover. Disconnect the wire and see if the pressure indicator light illuminates when the key is on. If it does, then the wire is routed incorrectly. If it doesn't then it means the pressure switch may be defective.
    Cheers,
    John T.

    54 TAV Legere; 61DS19 LHM BVH (son's); 71DS21 BVH; 73SM 3.0; 73SM EFI (Megasquirt); 73SM 3.0 (other son's)

  5. #5
    Tadpole
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    That settles my doubt about the brake light, and gives me the info I need to start looking into the oil pressure light problem. Thanks! I appreciate it!

  6. #6
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    The hydraulic is either on the priority valve as already mentioned or it will be located on the brake valve assembly in the driver's footwell. The switch mounted to the brake valve is often dirty and requires cleaning. It can also be out of adjustment and can be fixed by turning the small brass screw that is one of the contacts. The switch should open at about 110 - 130 BAR
    Last edited by faulksy; 9th July 2018 at 10:22 AM.

  7. #7
    Tadpole
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    Thanks! I will crawl under the car one of these days to see if I can identify the switch and correct the problem. When I have been down there, I did not see any loose wires or anything of the sort, and the light in the dash does turn on but goes off as soon as the car starts, therefore, I am hoping it is the adjustment you mention.
    Victor

  8. #8
    1000+ Posts forumnoreason's Avatar
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    if its on the brake valve you'll need to take the pedal shroud off to access which is where the pedals are. No crawling under car required. Just contorting into cabin drivers side.

  9. #9
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    Hi Victor
    Welcome aboard !! Great looking car there.
    Just a reminder about crawling under your Citroens. Only after you have put stands under it so it can not drop down on you. Safety for the hydraulics !
    Jaahn
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  10. #10
    Fellow Frogger! Don B. Cilly's Avatar
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    The pressure sensor would be under the suspension cover on an ID/D, at the brake button on a DS.
    So if this is a DS 21 and not a DSuper5...

    The hydraulic pressure light does go off as soon as there is some pressure in the system, not when the car is at full riding height.
    You have to judge that yourself (well the pump clicks off ;∑)

  11. #11
    Tadpole
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    Thank you guys!

    Yes, it is a DS, therefore, it should be inside the car at the brake button. That should make it easier to locate and check. However, big doubt: as described "The hydraulic pressure light does go off as soon as there is some pressure in the system, not when the car is at full riding height."

    That would make it seem like it works properly, as with the ignition open the light is on... but as soon as the engine starts, it goes off. My SM, which I am guessing should use the same logics of operation, turns it off until the car is up and ready to be moved, usually a mintute or so after I start it.

    So, how should it work?

    Thanks,
    victor

  12. #12
    Fellow Frogger!
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    The Stop light is triggered by fluid pressure - not height, and relates to hydraulic brake pressure: the big 'stop' light is telling you when there is minimum sufficient pressure in the system to operate the brakes safely, as that is more of a concern than a bumpy ride. In fact if your car suffers a pressure loss, pressure is prioritised for the brake circuit..

    Anyway, as with other pilot lights, it should light up when you first start the car - just to show that the bulb is working. As the car pressures up, the light will go out - even though the car may not yet be at driving height.
    Last edited by Budge; 10th July 2018 at 04:36 PM. Reason: incorrect information being provided
    1968 DS21bvh Pallas in Gris Palladium

    Restoration blog: https://ds-restoration.blogspot.co.uk

  13. #13
    Tadpole
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    Then, I guess it is normal. It does just as you describe: it turns on when ignition is open but when the car starts (and therefore starts building pressure) and after running perhaps two seconds, it turns off. If I turn the car off, and open the ignition again, it won't lit up the pilot light, I am assuming because it still has pressure... but if I let it sit for a while, then it will.

    So..... I guess my pilot light is working correctly and I was erroneously influenced by my SM in which it turns the light off until the car is up to riding height (perhaps some adjustment is different between this one and my DS21).

    Anyhow, I will work on changing the oil (per my other post) and I guess that will solve all my pilot light troubles.

    Thanks for all the help. Great forum!
    Victor

  14. #14
    Fellow Frogger!
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    Yes. From what you have described, i don't think you have a problem there.

    One last point about changing your fluid - and you probably know this already. The big LHM tank on your car has a 'min' and a 'max' mark. The fluid level in the tan needs to be between these two marks when the car is in it's heightest suspension setting. It's very tempting to assume you check the level with the car in 'normal' ride height - but that's not the Citroen way!
    1968 DS21bvh Pallas in Gris Palladium

    Restoration blog: https://ds-restoration.blogspot.co.uk

  15. #15
    Tadpole
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    Haha... thanks! I will have to learn the Citroen way.... but so far, I am delighted with the cars, so it will be time well invested!

    Thanks again!

  16. #16
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    So, as a summary and if I understand it correctly, the Citroen way is:

    When you open ignition, the main operation lights (oil pressure in engine, oil pressure in system and battery charging system) turn on but almost as soon as you start the engine, they turn off if everything is working correctly... and then, you need to pay attention to your suspension (that is has rissen the car to it's regular operating height) before you take off.... oh, and remember to remove the handbrake.

    Am I right?

  17. #17
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    Quote Originally Posted by DS21 + SM View Post
    So, as a summary and if I understand it correctly, the Citroen way is:

    When you open ignition, the main operation lights (oil pressure in engine, oil pressure in system and battery charging system) turn on but almost as soon as you start the engine, they turn off if everything is working correctly... and then, you need to pay attention to your suspension (that is has rissen the car to it's regular operating height) before you take off.... oh, and remember to remove the handbrake.

    Am I right?
    Correct!

    Sent from my LG-K520 using aussiefrogs mobile app

  18. #18
    Tadpole
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    Quote Originally Posted by Caisson View Post
    Correct!

    Sent from my LG-K520 using aussiefrogs mobile app

    Thanks!!! Glad to know my DS21 is working as it should.
    victor

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