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Wiring Nightmare
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Ray White



Joined: 02 Dec 2014
Posts: 6283
Location: Derby

PostPosted: Wed May 11, 2022 10:11 am    Post subject: Reply with quote

There is nothing worse than trying to un pick someone else's complete muddle. I realised this with my MG and ripped the whole lot out and started again.

However, my advise to anyone doing a rewire is to stick to the original layout and not get in out of your depth like I did. Embarassed
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Rick
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Joined: 27 Apr 2005
Posts: 22429
Location: UK

PostPosted: Wed May 11, 2022 12:34 pm    Post subject: Reply with quote

Ray White wrote:
There is nothing worse than trying to un pick someone else's complete muddle. I realised this with my MG and ripped the whole lot out and started again.

However, my advise to anyone doing a rewire is to stick to the original layout and not get in out of your depth like I did. Embarassed


Sometimes you have to go back to first principles I think, a test meter is essential kit to have nearby too, checking for feeds out from the switch with it set to different positions, and the matching feeds popping out in the wires at the equipment end, to make sure they're marrying up correctly.

RJ
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Vulgalour



Joined: 08 May 2018
Posts: 473
Location: Kent

PostPosted: Wed May 11, 2022 10:30 pm    Post subject: Reply with quote

Oof, this job. Okay, I accidentally put some confusing information in my initial post here... let me see if I can clarify.

For the LD10 there are two popular diagrams online. The first is the Lucas '46-7 LD10 diagram which is for the Briggs bodied car which has a slightly different light set up and the RF91 box.

The other diagram that usually pops up is a hand drawn one and supposedly for the Barker bodied car, like ours. It has the correct rear light layout and the RF95 box.

The full diagram I showed in the original post is the one that I've built from that information and the wiring in our car. The wiring in our car is a brand new Autosparks harness supposedly for our model, but came with no instructions, diagrams, or paperwork of any kind.

The whole point of buying the Autosparks loom was to make the job as simple as possible. When the car came to us it was partially rewired, partially original wiring, and seemed to be unfinished in this department so none of it could be trusted. However, the Autosparks loom has been a bit of a nightmare in a different way due to the total lack of information and the fact that their listed colour coding doesn't even slightly match the colours used on the harness.

Hopefully you're still following me here. The whole thing has been very confusing. I will be updating the diagram again and reposting it once Pat and I have had a chance to go through with the test bulb and multimeter to, as folks have said, get back to first principles.

Our car has a Lucas RF95 regulator box, and a Lucas PLC6 switch. However, the sockets on the switch don't seem to correlate with the only diagram I can find for the PLC6 switch functions. Additionally, I can't find a full break down of what each socket on the RF95 regulator box does, only what some of the sockets should do.

I cannot trust the two (unaltered, as mentioned above) wiring diagrams I have access to because they don't match our car. I can only use them as a guide to try and get me so far.

I've identified the functionality of the wires in the car. What I don't know is where the wires should connect at the ignition switch and the regulator box. I also don't know if the switch or regulator box are faulty and because I have no baseline to work from or any experience of this sort of job before this attempt, it's making it a very challenging job. Pat has even less experience on this particular job than I do, his experience is from installing audio equipment in the 90s and 00s.


Finally, on the big diagram I posted here, the wiring for the ignition switch is incorrect. Instead, this should be shown as per the connections for the ignition switch diagram. I will be updating the diagram again once I've gone through everything yet again to try and figure out what I've done wrong. I'm really struggling with this job, it's been the hardest thing to sort out since its felt like such a steep learning curve.
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Vulgalour



Joined: 08 May 2018
Posts: 473
Location: Kent

PostPosted: Wed May 11, 2022 10:53 pm    Post subject: Reply with quote

ukdave2002 wrote:
Ray White wrote:
ukdave2002 wrote:
I'm struggling to understand the issue here, the first Lucas diagram nails it, why deviate from that ?

Dave


This is different to mine. Here it seems L is for side lights; it is left unused on mine.


Sorry, I take my previous comment back back Embarassed looking closer at that Lucas diagram its been doctored, by I assume who ever put the coloured wiring overlay on the original Lucas drawing, a few obvious things are wrong:

On the Lucas diagram it shows the dynamo output going to "A1" on the RF95, it should go to "D"

The internals of the RF95 are also incorrect, it shows a fuse between A1 and F, this is incorrect the fuse is in fact between A1 & A2.

Unfortunately if the output of the dynamo has been wired to A1 it will have put the entire dynamo output through the RF95 series windings and depending how this affected the contacts, if its gone back to the dynamo Field (F) without any regulation the voltage output of the dynamo will have just kept rising to around 40v potentially burning out bulbs and Control box windings and or contacts.

Also is the car fitted with an RF95 control box, vehicles of that era could also have an RF91 control box, they are interchangeable but confusingly not labelled in exactly the same way. The graphic for the control box looks like the RF91, however its labelled as RF95, again I think is a badly doctored diagram.

Terminal L (Low) on the PLC6 switch is very seldom used, being originally incorporated for three lamp lighting sets where head/­side lamps on the wings carried bulbs with dim and bright filaments, the former acting as side lamps. Terminal L is alive in side position only and cannot be used for normal side lamp feed as it is dead in Head position. This terminal is used on motor cycle sets where it feeds the pilot bulb in the headlamp. Another application is on cars having a separate headlamp switch, wired from terminal L, while a pass light is wired from terminal H. In this case, position of normal "Side" becomes Sides, Rear and Headlamp, while position "Head" becomes Sides, Rear and Pass light.

Dave


The original Lucas diagram did show the regulator as RF91, I've been using it as a work-in-progress to keep track of what I'm doing but my focus was on socket locations and wiring colours, so I didn't think to upgrade the internal view for the regulator to match RF95. I've also been very confused about the correct order for the inputs/outputs on the sockets of the RF95 since the information I've had access to has seemed contradictory. This is probably more down to my inexperience than anything else.

I'm hoping I haven't damaged anything, though fully expect to have at this point. As mentioned in the previous point, I'll go back to the start and try again. It may yet be a job I pay someone else to sort out at this point to save me doing any more damage than I already may have. We'll have to see.
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ukdave2002



Joined: 23 Nov 2007
Posts: 4100
Location: South Cheshire

PostPosted: Thu May 12, 2022 7:17 am    Post subject: Reply with quote

Hi Vulgalour

If you post a picture of the current wiring on the RF95 and the PLC6 switch, we can figure out what's wrong.

Basically all the terminals on the RF95 labelled with an A* are output terminals, that offer fused/ unfused, ignition on/ignition off outputs.

• Terminal A is the output to charge the battery, and is normally connected to the battery at the starter switch/solenoid.
• Terminal A1 is used for lighting , as this is the largest load, the A1 supply is via additional series windings in the RF95 that influence the voltage contacts, this protects a battery in a low state of charge from additional voltage fall. It will go to the "A" terminal on the PLC6 lighting switch.
• Terminal A2 is connected to A1 via a fuse, and normally supplies things like the horn.
• Terminal A3 is just a connecting terminal that connects the ignition switch to unfused components like fuel pump & coil, it will go to “IG” on the PCL6 switch.
• Terminals A4 are again just connecting terminals a fused link to A3, generally supplies, wiper motor, trafficators, so things that you only want to operate when the ignition is on, but via a fuse.
• Terminal D to the dynamo output.
• Terminal F to the dynamo field.
• Terminal E is the ground/earth connection.

The RF95 is a clever compensated regulator, that takes in to account the load , state of the battery and temperature.

Post the pics and we'll figure it out Smile as long as nothing is damaged its will only be a 10 min job to correct things.

Dave
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peter scott



Joined: 18 Dec 2007
Posts: 7113
Location: Edinburgh

PostPosted: Thu May 12, 2022 1:48 pm    Post subject: Reply with quote

I thought this diagram was rather easier to follow than the regular Lucas diagrams: https://www.dloc.org.uk/ld10?pgid=jyqeazm3-150cc107-1551-4850-82a4-35b650df0fb4

Click on the expansion arrows top left.

Peter
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Bitumen Boy



Joined: 26 Jan 2012
Posts: 1733
Location: Above the snow line in old Monmouthshire

PostPosted: Thu May 12, 2022 10:24 pm    Post subject: Reply with quote

peter scott wrote:
I thought this diagram was rather easier to follow than the regular Lucas diagrams: https://www.dloc.org.uk/ld10?pgid=jyqeazm3-150cc107-1551-4850-82a4-35b650df0fb4

Click on the expansion arrows top left.

Peter


That's an interesting site showing some of the different bodies on these cars.
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