Instrument panel wiring issues DS23.
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Thread: Instrument panel wiring issues DS23.

  1. #1
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    Default Instrument panel wiring issues DS23.

    Hi all,

    Iím having some issues with the wiring behind the dashboard of my new-to-me 1974 DS23 5-speed and would like some input from the experienced Aussie Frogs brains trust. When I got the car a few months ago there were a few thin wires running under/on the carpet: one to connect the windshield washer pump to the wiper/washer switch and one piggy-backed onto the yellow plug behind the instrument panel from the coil.

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    The car has an AutoClima air conditioning unit, which was not operational, so I have removed all wiring, hoses, the (monster) compressor and the under-dash unit (ready for refurbishment in the near future) but I have been a bit too quick with loose wires removal to take pictures of the above thin wires and their location.. Ö
    I donít have many lights on the instrument panel: the STOP light, the oil pressure warning light etc do work (the ones which light up with the test button), but the blue and green head lights-on lights donít work, the general background lights in the instrument panel donít work, the indicators donít work, but the hazard lights do work, as well as both horns and the air horns. I have cleaned all terminals behind the steering wheel, cleaned the dim switch/rheostat and cleaned the indicator/horns switch internally, no luck. However, surprisingly the clock works well after some attention and even keeps good timeÖ All light bulbs in the panel are intact and have been cleaned, the wiring fuse holders have been cleaned, terminals deoxidised with emery paper and the fuses replaced.


    Where do the above lights get their power from? There is a (presumably green) melted wire which has been burned out in the past, which might explain the thin wires under the carpet to get things working again. Apart from that single wire the rest of the wiring loom is in good condition: no corrosion or green growth on the copper anywhere. I contemplate pulling a few new cables behind the dashboard to replace the thin random ones and call it a day for now, but need to know where to start. Iím learning as I go along, Iím not experienced in electrical fault finding (yet).


    Best regards, Erik.

  2. #2
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    It probably easier to tackle this in stages but first a bit of background might be useful. This diagram might differ slightly on the fuse colours but should otherwise match what should be installed.

    The instrument panel is the big rectangular object just to the left of centre in the diagram. It serves as a source of power for some circuits and a ground for others. Other useful diagram is the pinout for the multi plugs on the back.

    I'll start with the headlights as they are the most accessible. First question is do the headlights work? If they don't then there is either no power to the switch or the fuse holders are corroded. The instrument panel is provides the ground for the high and low beam, high beam and instrument panel lamps and power is supplied by the headlight switch (item 43) via the dim rheostat (item 34). The headlight switch also provides power for the clock, heater panel light, ashtray light and cigarette lighter light. There is no fuse between the battery and headlight switch so a lack of power at the switch could involve unwrapping the loom to fix.

    The only thing that would knock out the rest of the items you mention is the ignition switch. If the switch isn't getting power or not properly switching it will take out the cabin fans, indicators, windscreen wipers, rear screen heater and instrument panel warning lamps. It might also explain why there is a wire from the yellow connector of the instrument panel to the coil. I'd be grabbing a meter and probing the switch multiplug. With the ignition on there should be power on all the pins.

  3. #3
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    The connectors for the washer pump come out at the RH side of the scuttle. For cars with the pump on the left (DS23), there is an extension harness that plugs in and runs across under the scuttle rain gutter.
    Forget about the Autoclima unit for the moment because its wiring is not related to the dash. The relays for it are the green 'Sanor' boxes on the battery box. The front one is the control relay and should be switched via a coil piggy back if memory serves me correctly. Anyway, these do not go to the dash cluster.
    As your car won't have the remote starter solenoid at the battery, there is an additional yellow 'flying' lead behind the cluster that reverses the polarity to provide the solenoid on the starter motor with 12V rathe than earthing it as for the remote solenoid.

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    Faulksy, you're spot on, I think. With the ignition on I measure 12.6V only at the positive feed terminal of the yellow multiplug, the rest of the terminals show nothing at all. So, ignition switch has had it. The headlights work and I have connected both plugs to the rheostat together to take that out of the equation. The hazard lights work, but the indicators individually don't. Replace the ignition switch next?
    Last edited by tomatoes4all; 11th February 2020 at 03:48 PM. Reason: correct spelling mistake.

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    Thank you David S, as soon as the dash issue has been resolved, that's next on the list.

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    Are you measuring the voltage only at the white, yellow and green multiplugs for the instrument panel or have you also gone looking for voltage at the white multiplug that connects the ignition switch? Its usually buried to the left of the steering column near the switch and has black, blue, red, yellow and green wires. You can see it at the bottom right of this photo.



    If it is the switch the the good news is it can be taken apart and cleaned

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    You could go for "easy" first: I don't even know if it's feasible on the later ignition units, but you could try to squirt switch cleaner in it first, then twist the key to see whether that cleans (hopefully) dirty contacts. I'd probably disconnect the battery if i was going to flood the ignition switch.
    1968 DS21bvh Pallas in Gris Palladium

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

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    The key and steering lock assembly is physically separated from the switch assembly so I'm not sure spraying switch cleaner in will do much. It's pretty easy to remove the switch block, I'll see if I can find a photo later

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    Quote Originally Posted by faulksy View Post
    It probably easier to tackle this in stages but first a bit of background might be useful. This diagram might differ slightly on the fuse colours but should otherwise match what should be installed.



    The only thing that would knock out the rest of the items you mention is the ignition switch. If the switch isn't getting power or not properly switching it will take out the cabin fans, indicators, windscreen wipers, rear screen heater and instrument panel warning lamps. It might also explain why there is a wire from the yellow connector of the instrument panel to the coil. I'd be grabbing a meter and probing the switch multiplug. With the ignition on there should be power on all the pins.

    Just a thought! I have had to repair an ignition switch before! The key would turn but nothing happened. It turns out that the key barrel turns the switch via a very small roll pin pressed into the shaft of the key barrel. This locates in a plastic disc that is the turning part of the actual switch. In my case the roll pin had sheared and the key barrel shaft was turning but not rotating the switch disc. A very simple fix is to knock out any remnants of the roll pin, insert an appropriate size drill shank and cut off the excess to match the slot in the turning disc of the switch. The fix is much stronger than the original roll pin, and is still working.
    Cheers Gerry

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    Faulksy, I've just checked for voltage at the white multi plug, which connects to the ignition switch; there is 12.6V at three of the six terminals, all on the right side of the plug and are red, black and green.

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    Hi Gerry, that sounds like a good solution if the switch is the culprit. I've just had a look at what the usual suppliers want for a RHD ignition switch and that's repair only, not a new one: about AU$ 600.....

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    You should be able to hotwire it rather easily for the purpose of testing. That will also prove/disprove the switch being the problem. I'd thought you could buy the switch portion separately to the entire lock assembly. While you are there, plenty of people have disabled the column lock by removing the ring from the column or removing/cutting the locking rod.

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    Default DS Ignition Switch Dismantling 101

    To reply to your last post, with the key on you should have 12v on all the wires.

    Step 1 is to remove the switch from the car. This is either very easy or very hard depending on weather it has been done before. You will need to remove the steering wheel pod and all the screws that secure the lower edge of the dashboard 2 of which are behind the heater control cover. If you pull the bottom edge of the dashboard forward it will reveal the single bolt and 2 security nuts that hold the switch in place. Options for removing the security nuts range from hammering a socket on to cutting a slot for a screwdriver, either way a good blast of WD40 is going to be your friend. with the bolts undone, turn the key to disengage the steering lock and then wrangle the switch out through the hole normally occupied by the instrument cluster.



    Two thin metal bands are used to hold the switch assembly to the key assembly. You'll need to find something sharp and strong to prise up one end and expand the ring enough to slide them off. Start with the one closest to the aluminium housing as this holds the switch to the lock. With the ring off, turn the key to on and pull the switch assembly off the lock assembly.

    Prise up the second metal band to release the two halves of the switch assembly. The final photo shows the actual switch contacts which as you can see get very dirty over time. This one wasn't helped by going through a fire. Clean, grease and reassemble in the reverse order of disassembly.

    If the switch is working, red should connect to blue, green to mauve and black to yellow.

    White is the starter. Blue is power for the coil and the others depend on model and year.
    Budge likes this.

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    Thank you all for the responses, especially thank you to Faulksy for the step-by-step instruction to remove and clean the ignition switch! Indeed it was the ignition switch. It wasn't too hard getting that removed from the dash, neither was opening the switch itself. Inside was a thick sticky paste of grease mixed with dust, but more to the point the little pin that Gerry spoke about was bent and the other half was missing, rolling around inside the greasy paste. A replacement pin was easily made from a drill bit, carefully tapped in and cut off with the grinder. However, getting it all back together after cleaning and regreasing was a chore-and-a-half; the two brass discs refused to stay in place when assembing the unit and it took me a long time. After all that, the steering lock was hanging up at times, preventing the key from turning smoothly, as it had done often before, so I cut the locking bar off and drilled and tapped a grub screw into the housing to be able to turn the key. It's not how I usually repair things, but all is now well. Everything but the tachometer and the instrument panel lights work, so I have made good progress. I will now focus on the wiring, but at least the car is now driveable. Cheers, Erik.

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    Good to hear that things are coming back to life.

    Sewing machine oil works a treat for getting the steering lock working smoothly but as you've disabled the mechanism it's a moot point.

    The tach gets pulses from a red sleeved spade terminal on the negative side of the coil.

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