Electrical Repairs

This section covers the repairing of the loom and the modifications introduced.

As I eluded to earlier on in the project, the electrics were an area of the restoration that
I was really looking forward to undertaking. 

So this section describes the work I’ve completed and hopefully, if you are reading this web site
for information for your own restoration, you will find it helpful.  


Section A : Understanding The Wiring on an SS1
Section B : Main Aims and Planning
Section C : Existing Faults
Section D : Modifications
Section E : Testing the Electrics
Section F : Repairing the Headlight Motor
Section G : Finishing the Electrics

A. - Understanding the Wiring on an SS1



The first and probably most important part of repairing the electrical systems was to fully understand the original wiring system and diagram.  Fortunately a pretty good wiring is available from the RSSOC Club.  This diagram is in the format commonly used by Ford in the 80’s & 90’s, that is the battery +ve and subsequent feeds start at the top of the diagram and “flow” down to earth points (usually the chassis) at the bottom via the switches and the components.  A simplified diagram is shown below:

I like using this style of diagram as opposed to the type that shows the components in plan view as if they were positioned on the car. Although this type helps with where the cables run from/to, I find it more difficult to visualise what the circuits are controlling. The “flow down” style can be easily used to visualise what happens when switches are turned on/off.  But this is only my opinion.

One important step is to copy the wiring diagram and enlarge it up to at least A3. One of the “golden rules” I learnt as a draughtsman was to never mark/draw on or otherwise deface your master information – always use a copy.

I ran off several copies and used them as follows:

  • I marked up one print with highlighter pens used to help indicate the major parts of the feeds.  See below for more details.
  • A 2nd print was used to add comments about what work I wanted to do.
  • A 3rd copy was used to try and draw the modifications on before transferring these to a new electronic based version of the diagram.  (See later on in this page for more details about this new version.)

As mentioned in 1) above, one copy of the diagram was used to show the main feeds in the diagram.  This is probably the single most “enlightening” step you can do to help understand any vehicle wiring diagram.

These main feeds are (and by all means use your own colour scheme).

a) Circuits that feed constantly from the battery (Yellow) including those live after a fuse.

b) Circuits that are only on after the 'radio position' is selected (Blue).

c) Circuits that are on when the ignition is on (Green).

d) The 'start' position circuits (Pink).

Take this diagram, highlighting the circuits - see how instantly the circuits become more manageable.

Thanks to the RSSOC for allowing me to reproduce these sections of the SS1 and Sabre wiring diagrams.


Lighting Information

Lighting circuits on the SS1 are probably the most difficult part of the electrics to fully understand.   They rely on about 7 relays to operate both the bulbs and lift motors!

I’ve produced an SS1 Headlamps Guide which explains how the lights work and includes some trouble shooting tips, testing etc. It's well worth a read and may prove indispensable if you are struggling to understand the lighting circuits.



B. - Main Aims &
Planning the Repairs


Main Aims

I had two main aims to fulfil: 

a)  Repair the burnt out wiring and ensure it would not overload again

b)  Protect other circuits that could overload by installing some more relayed fuses..

To be in keeping with the methods of construction and style of the wiring I decided to re-use as many of existing wires and fuses, etc as possible, this will become more clear as I explain each stage later.

I used parts that matched the originals as far as possible and the colour codes for the new cables.  I managed to keep in line with the BS for vehicle wiring.  An MG web site in America is an excellent source for the colours of wiring circuits and although I could not stick exactly to the scheme due to the colours already used on the car, I came pretty close and they are all “in the spirit” of the main rules of thumb.

 Thanks for the MG site for this information.



Quite a lot of time was spent designing the repairs and modifications I was about to undertake.  At least 5 evenings were spent sketching how the work would be done, what routes the cables would take, what parts I would  need, etc, etc.  It was surprising how much thought needed to be done upfront.  And this work paid dividends as all of the work went extremely well, but heh! that’s giving away the ending!



C. - Existing Faults


Finding the problems

When I bought the car the previous owner said that the auxiliary lights did not work but “… they would be on easy repair” – yeah! right! what he'd also forgot to mention were the other problems!

I started by investigating what the wiring was like inside the loom as I would be re-taping it later anyway.  What a filthy, sticky job that was.  With all the loom tape removed I could see that not only had the auxiliary lights cause problems but that distributor/coil wiring had in the past “gone wrong” and had melted another wire in the loom.  At least that explained all the extra strange coloured wires running in the engine bay with a ‘Skotch-lok’ fixing it to the fuse box!  All this work had been undertaken by a “professional auto-electrician” as well, you know the type that you are supposed to use if you don’t know what you are doing – in my opinion an inhabitant from the monkey house at the local zoo could have done better!  Anyway, that was history and it was not about to repeat itself.

The final small problem that appeared at this stage was the mystery of the missing heater fuse – the answer was the heater motor was seized.

Tackling these problems one at a time I formulated a plan of action to repair them and then having done that to improve other circuits.  I also took this opportunity to replace the original mild steel relay/fusebox mounting plate as it had almost rusted away.  I used some 2mm aluminium to create a new plate and installed this under the two terminal blocks.

New Fuse Box Support Bracket

With the Lid on


Front Auxiliary Lights

Faulty earths on the lights had caused the earth wires near the switch at the dashboard centre console to overhead as the auxiliary lights had been badly installed into the front spoiler. Instead of using a ring terminal to earth the units the copper wires had been stripped and wrapped around the mounting bolts, which over time had worked loose and (as with car electrics) they had found their own earth via the switch’s bulb.

Two things to do here were:

a)     Removing the power from the switch by introducing a relay for the lights and

b)     Ensuring the earth for the new lights was done to the highest standard.

This diagram shows the working sketch for this modification:

The N feed was taken from a new multi-way feed housed in a Maplins project box  this was fed from a new 6mm” N cable directly bolted to the battery terminal as not to overload the existing positive power lead.

The +ve Battery Temrinal


Ignition Wiring

Obviously at some point in the car’s history the ‘black box’ on the side of Ford distributor had gone ‘full short’ taking out the white feed wire from the ignition switch, in fact as you can see from this photo there was very little left of the original cable.

Part of the damage in the loom 

The white cables from the ignition switch are not all protected by fuses.  This was true of the ignition module, so to prevent this problem occurring again I introduced a relay which was switched from a white ignition feed and took its power from the new multi-way power box.  The output side of the relay went through a new 5A fuse housed next to this new relay bank.



D. - Modifications


New Fuse/Relay Box & Feeds

As mentioned above I incorporated a new relay / fusebox assembly to house the additional components in.  This was sited at the front of the inner right hand wheel arch liner, where the washer bottle is usually located.  The washer bottle was relocated to the corresponding position on the left hand inner wing and the wires extended across the armature.  The old washer pipe was replaced with a new length now running down the left hand wing to the dashboard through a new hold in the bulkhead. 

The washer bottle now of the left hand wing

Back of the new Relay/Fuse Bank part way through installation

The new relay/fuse bank consisted of 2 x 4 way relay holders and a 1 x 16 way fuse holder.  Although I only planned to fit 3 extra fuses (I would be utilising the existing fuses in the original Reliant box for the rest).  I bought the large new fuse box as it clipped to the relay boxes and created an excellent installation.

Finished installation next to the new feedback connector box
(no lids fitted here, and the loom needs taping up!) 

All of the parts I used are available from Vehicle Wiring Products.  The boxes are easy to use and of high quality.  I could have used cheaper relay mounts and a smaller fuse box, but they would not have afforded the same level of protection to the components. 

During all the work on the electrics I soldered the wires into the terminals as well as crimping them.


Horn Relay

This was one of the rest of the improvements that I made to the car to reduce the current passing through the horn push button, maybe not for the current horns, but just in case I fit some air horns later.  The diagram below shows the new circuit:


Front Fog Lights (New)

When I was looking for some new lights to replace the auxiliary units I found some Ring units which had combined driving and fog lights.  I picked these up for a reasonable price as the shop I got them from were selling them off.


The lights fitted really well into the nose cone.  I made up a short loom from the lights (about 500 mm long) to allow them to be easily removed from the car.  I used a 4-way Ripault connector for each light.

Both the fog and driving lights have separate earths.  Here is the schematic for the wiring:

The fog light relay is switched from a new switch (thanks to Chris for supplying this) on the centre console, which in turn is fed from an ignition controlled relay. The new switch  controls the relay to power the lights. 

New Fog/Auxiliary lights fitted to nosecone


Rear Fog Lights

On the original car the rear fog lights were fed via a switch, having its feed from Relay 8, which was live only when the headlights were switched up and had raised.  My experience of driving in foggy conditions was that the headlights can impair the visibility, but if the headlights are not up, then the rear fogs would not operate.

To overcome this I installed another new relay and fed the coil side of the relay from the sidelights output of the lightswitch instead.

Here is the wiring modification, note that the original feed from the headlights has been left available, just in case the MOT guy wants to see them working in conjunction with the headlights:


Relaying the Main Beams

Although the main beams and auxiliary lights are fed by relays, and therefore the switches are protected, the dipped beam full current goes through the multi-function switch.  This may, over time, and if I ever fit any higher wattage bulbs, cause trouble with the contacts.  To prevent any problems I added a new relay in as shown below:


Radiator Fan

The final modification was to the rad fan circuit.  This was one area that definitely required a relay.  I left the original fuse protecting the temperature switch (reducing it to 5A) and introduced a new one just for the relay/fan feed circuit.  You can see this here:



Relay/Fuse Layout

That completes the modifications to the wiring.  The layout of the new relays and fuses I used can be seen below:

And the new feed box for the power to the relays can be seen here:

View of the new feed box with the lid removed 




E. - Testing the Electrics


Earthing and Equipment

Apart from some basic continuity testing whilst actually carrying out the work, no real testing of the electrics had taken place.  I had purposely left this so I could go through the circuits in a methodical manner all together.

I used a digital voltmeter, testing screwdriver and a 12v test lamp made from an old style BL indicator lamp\rubber mount.

To do the testing I needed power, but the battery I had removed from the car was completely dry and dead.  I thought about topping up and recharging it but I did not know the history of the battery and therefore it still could have been of no use.  I opted instead for a new one from Halfords.

With the new battery bought and installed temporarily, on the recently overhauled battery tray I could begin testing. But I had no earth!

I used the original battery lead to go from the battery to the lift lug/earth point and after a quick rummage in my electrical parts bin I found a suitable earth braid to connect the engine to the chassis.  I utilised one of the Ford leads rescued from the Orion to go from the engine earth point to the front armature to improve the earth for the lights, etc.

Battery Installation 

The original 25mm2 red lead from the battery +ve to the starter was still in good condition so this was re-installed after a clean up.  Also attached to the +ve terminal were the 2 brown (N) 6 mm2 feeds for the main circuits. 

I replaced the alternator main wire at this as well.


As so not to put myself at risk, the first test was to see if there was a dead-short between the battery positive cables and earth.  As you can imagine, if there  was, at  least a fuse, but more worryingly, some cables and maybe even the battery could have been damaged.

With no dead short I tentatively connected up the battery positive cables and tightened the connection.  This was followed by the negative lead to the engine.


It is always safer to undo the –ve lead first when removing a battery and leave the +ve till last. This is just in case your spanner/socket touches an earth point whilst working on the +ve lead. If the –ve lad has been removed then the +ve terminal cannot short out on the car.

When reattaching the leads start with the +ve lead first, then the –ve one.


Testing Method

I split the testing into two stages:

a)     Testing all the ancillary circuits like the lights, heater, radio etc.

b)     Testing the ignition feeds to the coil and the starter motor.

  The multi-plug I’d introduced to tidy up the distributor/coil wiring (in fact using some modified Orion wiring as the SS1’s was in such a state) was left disconnected so the coil/ignition unit would not overheat as the electrics would be on for quite a time. 


Test Results

It was great to see nearly all the circuits working first time, including all the modifications I’d made. The only small problems I had were with the bulbs not earthing properly in their holders (front side and a couple of rear lights) and one of the original relays’ terminals had been pushed out of it mounting point causing an intermittent lighting fault.

With these two sorted I could move onto the only major problem with the electrics….the usual winking headlights!



F. - Repairing the
Headlight Motor


The Damage & Repairing the

Whilst testing the headlight circuits I was disappointed to find the LH headlight did not motor up on its own.  If I turned the manual knob on the bottom of the motor to raise it up it would then motor down on it’s own.

A quick check of the various feeds and earths to the motor pinpointed the problem down to the internal switches.

See my ‘SS1 Headlamps Guide’ document for more information on how the lights should operate.

I proved the switches were at fault by bridging the in & out wires the switch should have connected inside the motor. When connected the motor raised up the light unit with no problem.

To find out what was causing the motor not to raise up I took the motor assembly off the car and began to strip the switch box down. It did not look good even when I’d taken just the cover plate off, it looked like a lot of water had found its way into the unit at some point.

Five wires connect into the motor, two go directly to the actual motor (controlled via the relay mounted next to each motor assembly on the front armature) and the three remaining wires are a common and two feeds which when connected control the relay mentioned above to operate the motor.

On closer inspection the were two faults with the switching unit

a)     One of the diodes had been burnt out and was basically a pile of ash!

b)     The contact at the end with the burnt out diode was not mating with the copper “switch” strip

The photos show clearly the mess in the switch box….

The damage inside the Headlamp Motor Switchbox 

The coverplates showing the water damage

A new diode (3 Amp) was purchased from Maplins at a cost of 10p and the contact pad was rebuilt with some careful soldering, the diode was then soldered to the pad and the feed cable

The new diodes

Here you can see the finished repair…..

The repaired moter

The cover plate and new gasket



To finish off the renovation of the motor I cleaned up and sprayed the metal switch cover and cut out a new gasket. When re-assembling the lid I used some Blue Hylomar to seal it down and some silicon sealant to seal around the wires to stop any water ingress from here.

I thought that the copper “switch strip” was bolted to the body of the switch box  as standard but the RH light motor had the strip riveted in place and looked in far better condition, in fact it looked like new. I concluded that the LH motor must take far more punishment from the elements.

When the completed lift motor was re-installed into the car and tested it worked fine! This concluded the work on the lighting problems.



G. - Finishing the 


Tidying the loom

What had I done? – Although everything was working the loom was just hanging with all the cables on show and looking very sorry for itself. I needed to finish off the job by taping and clipping the loom up.

The loom awaiting re-taping 

I started by carefully pulling the loom into position and using small black cable ties I started to form the bundles again. This did not take too long and it was soon time to start to tape up the loom with the non-sticky black loom binding.

Binding the cables up with the loom tape was at times very time consuming when trying to wrap tight into corners and at fiddly junctions in the loom. Having said that the easy straight runs made up for this and after about 4 hours work the loom was all taped up and looked resplendent in its new shiny black coat.

The loom after being taped up, ready to clip back onto the crosstube



The dashboard crosstube could now go back in for good and was bolted in place not forgetting to fasten the earth terminals behind the bolts where required at either end. Any areas that looked like they could rub against and thing solid were treated to a wrap of foam strip and cable tied in place. 


Mirror Harness

The electric mirror harness was ran next to the main harness and its ends passed through the ‘A’ posts ready for when the doors go back on.

The 'A' post wiring waiting for the doors

The next step was to install all of the small electronic units under the dashboard and reconnect the multi-plugs to the rear loom section. The shorter looms I  had made up for the engine bay electrics went in and connected to their respective components. This was a good idea to introduce Ripaults multi-plug connectors for these components.


This concludes as much as I could achieve on the electrics for now.

The next section starts covers the final stages.