D Special wiring problem.

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Tadpole
Tadpole
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Hello All, My D Special has a bird's nest wiring loom that looks far from original. It has relays hanging everywhere. I have a problem on the ignition circuit in that when the key is in the ignition position the wire to the coil shows a short. I have disconnected everything in the engine bay so it must be either in the switch or somewhere else on the "ignition on" circuit. Is there anyone in Melbourne that can work on these electrics as I have limited mobility and can't climb under dashes and the like to take out the ignition switch to further track down the fault?
Thanks.
 
You have to remove the dashboard completely to get at the main wiring loom. The ignition switch can be got at by just removing the instrument cluster.

On a DS there isn’t just one “ignition on” input or output from the switch. Power for the coil arrives at the switch on the red sleeved wire and goes out on the blue sleeved wire. It’s not fused and doesn’t go anywhere else besides the coil.

Any auto electrician should be able to work on the car. The wiring diagrams are available in manual 814 here https://www.dropbox.com/sh/tv0b25gpmd5ux8e/AAAhvSwJoeCeptJM3g7TENBQa?e=1
 
It was common to add relays for the headlamps so that may explain part of it. You might best to remove all the extraneous add-on stuff and get it back to the factory loom if that remains possible. If it's been cut and joined all over the place, you may not be able to do that, but often things like relays are just plugged in to the original circuit and take a power source from the battery with a separate fuse.
The ignition switch supplies the coil and that single 12V+ wire is easily removed from the spade terminal at the coil to check if the short is before the coil. Perhaps, the coil shorted internally or the ballast resistor incorrectly connected?
 
Coil is fine.
When I remover the spade from the coil and check the wire relative to b+ I get minus 12 volts. This is with the key in the on position. If returned to the off position zero volts. If the coil is the only thing energised from this circuit (as advised) then the short must be in the switch. I shall remove the dash and investigate further.
 
If you get -ve 12V at a terminal that's meant to be battery +ve then reverse the polarity of the multimeter leads. The coil is not the only circuit going via the ignition switch. Look at the wiring diagram and you will see it also feeds other circuits, mostly via the fuses. It's likely not the switch, so don't make work for yourself taking the dash out until you really have to. The wiper motor wiring on the motor has a habit of crumbling, so that's worth a look.
 
David S said:
If you get -ve 12V at a terminal that's meant to be battery +ve then reverse the polarity of the multimeter leads. The coil is not the only circuit going via the ignition switch. Look at the wiring diagram and you will see it also feeds other circuits, mostly via the fuses. It's likely not the switch, so don't make work for yourself taking the dash out until you really have to. The wiper motor wiring on the motor has a habit of crumbling, so that's worth a look
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The minus 12 volts on the coil lead relative to the B+ indicates a short. I presume the alternator field supply and others has to come via an ignition "on" . I don't have anything on the fuses mounted on the firewall when the ignition is "on".
 
-12v sounds a bit odd. The positive multimeter lead needs to go into the coil spade terminal and the negative to any earth.

The ignition switch does feed other things but they all have separate terminals on the switch.
IMG_6828.jpeg


Most of the fuses sit between the dash switches and whatever they are powering e.g headlights. The red and green fuses sit between the battery and ignition switch so should be permanently live. If you’re not getting power on any fuse with the key on or off then that in itself is a problem
 
faulksy said:
-12v sounds a bit odd. The positive multimeter lead needs to go into the coil spade terminal and the negative to any earth.

The ignition switch does feed other things but they all have separate terminals on the switch.
View attachment 241169

Most of the fuses sit between the dash switches and whatever they are powering e.g headlights. The red and green fuses sit between the battery and ignition switch so should be permanently live. If you’re not getting power on any fuse with the key on or off then that in itself is a problem
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It's not odd if the -ve lead is on the + battery terminal and the +ve lead is on the wire. Thanks for the help, the diagram of what's on the switch is great. Not having anything on the fuses is a problem. The switch energises the starter solenoid but that's all that works from the switch. The coil has to be jumpered for the engine to start and if the coil wire is attached the solenoid wants to kick in in several positions of the switch. No work tomorrow so I shall investigate further.
Thanks again all.
 
Be aware that if the wiring diagram you refer to shows a remote start solenoid and a single wire to the starter then the polarity of the starter wire is reversed vs when you don't have that remote solenoid at the battery. Then there is an extra lead (usually yellow) behind the cluster to put 12V+ down that line to operate the solenoid on the starter.
 
i would be checking the supply on the red wire terminal 1. it doesnt sound to me like a switch problem. you have a supply on 7, and it would be worth checking 4
if you have 12v at 1 then i would suspect the switch
 
Citroen didn't make it easy. You need to remove the screws along the underside of the dashboard so the lower edge can be pulled forward to reveal the ignition switch fixings. directly below the switch. There is one bolt and 2 anti theft nuts which are smooth and conical. Most people hammer an undersize socket onto the nuts or use a pair of vicegrips to turn them. Once you get them undone, turn the key to "on" and lift out the unit.

in post #6 you say there is 12v on the coil feed wire with ignition on and 0v with ignition off. based on that, the switch is working fine. Do the cabin fans and indicators work?
 
faulksy said:
Citroen didn't make it easy. You need to remove the screws along the underside of the dashboard so the lower edge can be pulled forward to reveal the ignition switch fixings. directly below the switch. There is one bolt and 2 anti theft nuts which are smooth and conical. Most people hammer an undersize socket onto the nuts or use a pair of vicegrips to turn them. Once you get them undone, turn the key to "on" and lift out the unit.

in post #6 you say there is 12v on the coil feed wire with ignition on and 0v with ignition off. based on that, the switch is working fine. Do the cabin fans and indicators work?
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i think he means there is an earth with the ignition on and and nothing with ignition off. If there was 12v at the coil it would run .

which in my mind points to red wire on terminal one being connected to earth (maybe its not the red wire on 1 ?) or an internal fault in the switch supplying the earth. i more suspect the former.
 
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I don't appear to have a feed to the switch. I have disconnected the plug from the back of the switch and there is still a short on the positive wire from the alternator ( which is not connected to the alternator). I am not able to send pictures but there is a bundle of wires that the alternator positive is connected to that doesn't look right. Which wire/s supply the switch?

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The factory did use those crimped splices in quite a few places but that doesn't look quite right.

The alternator B+ wire is a direction donnection to the battery with a few splices for the 2 main power feeds. With the amount of exposed copper you have there I'm not surpised there is a short somewhere. As a starting point i'd be insulating all the bare copper and seeing if that changes things. Pretty much the eintire loom is black or green cable which makes it really hard to identify wires mid run. You really have to unwrap the loom to work it out.
 
Almost there. I have got a feed to the switch. Just need to sort out the indicators and put all the instrument and switch things back.
Thanks again Fellows.
I hate admit it but I the problem was due to something I did a while ago, but I don't want to think about it. Alright I had the starting solenoid relay wired backwards and of course a DC relay doesn't care which polarity it sees. Hence the solenoid operated fine but it was earthing through the ignition switch and thereby my "short" appeared.
faulksy said:
The factory did use those crimped splices in quite a few places but that doesn't look quite right.

The alternator B+ wire is a direction donnection to the battery with a few splices for the 2 main power feeds. With the amount of exposed copper you have there I'm not surpised there is a short somewhere. As a starting point i'd be insulating all the bare copper and seeing if that changes things. Pretty much the eintire loom is black or green cable which makes it really hard to identify wires mid run. You really have to unwrap the loom to work it out.
Click to expand...
 
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