Fan and Horn +

[baganz.sven@web.de]

Dear forum colleagues,

sorry for bothering you with a rather simple question.
The pre owner of my 1971 E V12 has put a switch in the cockpit to operate the fans manually.
Now I'm trying to bring everything back to normal with automatic operation via the Otter switch.

If I read the wiring plan correctly the horns and the fans are both connected to the line fuse close to the battery.
In my car the cable from the fuse is connected to C2 of the horn relay (I hope it is in the right place in my car, close to the battery).
Thats OK from my point of view.

But the cable to the fans (brown wire) is not connected.

Where is the connection point of the cable from the fuse and the wire to the horn relay originally located?
Are they normally connected at the C2 point of the relay?

How does this connection look originally?

On the attached pic you can see the wire from the fuse to C2 (now black, should be brown)and the disconnected brown wire to the horn relay.

Thanks for advice

Sven

[cactusman]

Afraid I can't answer your wiring question but adding a discrete over ride for the otter switch is not a bad idea...a lot do it... as the otter switches have been known to fail. A manual over ride saves a boiled engine.

[baganz.sven@web.de]

Hello Julian,

no problem, basically it is easy to connect the two wires
but I want to make it close to original spec.

I have already bought a "coolcat" temperature switch kit which will replace the otter switch.
You won't believe how the wiring actually is done in my car.
The owner has used massive copper cored cable from his house electrics!
Not flexible at all!

So my E really needs help

Best regards

Sven

[Heuer]

This is one for Marek - hopefully he will be along to offer advice.

[vee12eman]

Hi,
The Horn relay should look something like this:



The Wiring may be clearer in this diagram:



I have a clearer copy if you pm me.

You are correct that the fan relay and horns take the supply from the same fuse on the engine frame.

BUT, before you connect any removed cables, consider why they were disconnected in the first place. These wires carry a lot of current, easily enough to melt the wiring loom or worse start a fire if there are shorts hidden inside the loom wrapping or anywhere else.

W1 and W2 are the "winding" connections, i.e. the control signal from the switch (horn push in the case of the horn and thermo switch in the case of the fans. C1 and C2 connect the current to the user circuit - in this case the horn or fans. Making the "W" connections provides the signal to connect the user circuits to power, in this case by connecting via the thick brown cables. Old Lucas relays are not as sensitive as modern devices and can generally be connected in either orientation, but I suggest sticking with the original wiring diagram. Lots of info on Lucas relays if you Google it.

I use a coolcat switch with a 75 degree setting, but rewired to use individual relays, one for each fan in case of relay failure. I have modern fans which draw more current and the single Lucas relay I bought (a modern replica) wasn't up to the job - fusing closed at the first test. I instead employed two modern relays to do the job, with separate relays for each fan as described.

The wiring diagram for this is in the knowledge base:

https://www.dropbox.com/s/a4ubnltt94dnq ... g.pdf?dl=1

I just re-read and saw the bit about additional non-flexible house wiring. Be very suspicious of the quality of such a bodge. I recommend new wiring...

Try Autosparks.

Hope this helps

Regards,

[baganz.sven@web.de]

Hello Simon,
thanks for the reply.
Basically my horn relay is connected in the right way ( only the brown wire on your pic has been replaced by a black one in my car)
The black wire in my car is connected to the line fuse.


Horn wiring seems to be OK (and works) but I do not know where the + line to the front should be connected.
In the wiring diagram I can just see that they should be connected to the fuse but not how .

Should there be e.g. an y cable at the fuse?

So C2 of the horn relay is connected to the fuse like in the diagram.
But where to connect the wire to C1 of the fan relay?

The disconnected brown wire on the right side of my photo is the wire to the fan relay!

Sorry that I can't describe it better.

sven

[vee12eman]

Hi Sven,

I do not claim to be an expert on wiring and although I completely re-wired my car, this was ages ago. I still have some of the old looms on my shelf, but largely I cannibalised these for spare lengths of cable. I may be able to find the old loom and trace where the cable splits, but think it is long gone.

However, I will try to answer your question and cover all eventualities.

From memory and the wiring diagram, a single brown cable supplies both fan and horn relays. The cable is one of those connected to the power stud on the R/H engine frame, just above the Ignition Voltage regulator and attached by a heavy cable to the +ve battery terminal. This cable enters the loom running along the R/H engine frame and has a loop which exits, then re-enters the loom – this loop includes the fuse holder you refer too. From there, this cable goes down to the fan relays. Coming off this cable is a branch which feeds the horn relay. The joint of the branch is hidden (I think) within the loom wrapping, close to the exit point on the loom. I think this is your disconnected brown cable adjacent to the fan relay and is now replaced by the Black cable you describe. The disconnected cable may still have continuity to the fan relay connection, through the branch and joint described.

If the original cable is broken between horn relay and power stud (including the fuse holder), then the original line will be unable to supply either horn or fan relay. On the other hand, if the branch had come disconnected from the main cable (possibly hidden inside the loom wrapping), then there would still be a supply to the fan relay, but not the horn. You could fix this by unwrapping the loom and reconnecting - be sure to insulate well afterwards.

You do not say whether the fans receive power from the brown cable and fuse or from a new cable, only that the fans are switched on and off by the manual switch in the dash. This is probably connected to a different control circuit, connected to the fan relay winding connections - W1 and W2, correctly, this should of course connect to the otter switch or in your case the new Coolcat switch.

It seems the previous owner overcame a problem using the new black cable to supply the horn relay, which you say runs from relay to the fuse, indicating that the power stud to fuse section of the cable is OK. Again, I am not sure how the fans currently receive power, only that they are controlled by the dash switch. This switch presumably bypasses the thermo switch for the fans and activates the fan relay, but alternatively may supply the fans with power directly, not using a fan relay at all. The latter is pretty undesirable as the switch will not like the power draw from the fans and will likely be arcing every time it is used.

You need to isolate the cable from the power stud and any relays and find out if the fuse holder has continuity to the power stud connection (you have to disconnect or the continuity check may pass through other components). If it does, then see if the fuse holder itself is undamaged and has continuity to the (currently disconnected) brown supply to the horn relay. Also, you need to check if there is continuity from the fuse holder to where the cables exit to supply the fan relay – as I have modified my car, I am unsure of the exact location, but I think it is near the rear mounting for the bonnet gas strut. Whilst disconnected, do an insulation check by ensuring no continuity from the cable to the body/frame or other components.

If these are intact, insulation seems to be OK and the fuse holder is not corroded or damaged, you may be able to restore the wiring by re-establishing original connections, fitting the fuse and reconnecting the horn and fan relays. BUT, as I said before, be aware that the previous owner disconnected and changed the circuit for a reason and if the reason was that the brown cable had become damaged and despite your tests, due to insulation failure, is now in contact with either car body/frame or other cables, then you run the risk of shorts, sparks, melted cables and/or fire. There is a lot of current available to this brown cable, which is directly connected to the battery.

Prior to reconnecting any cables, have a good look at the loom running along the engine frame – see if any of the cables show signs of damage – either chafing or melting, if you find evidence of this, the loom should be replaced.

I suggest that if no damage is apparent, the cable from the power stud is ok and currently connected with no problems, continuity exists down to both the horn relay supply (currently disconnected) and to the supply to the fan relay, then you could fit a small fuse to the holder and test – if that blows when fitted (as opposed to when either horn or fan is operated – the small fuse should blow in any case at this point), then the loom is damaged and should be replaced – certainly it should not be used to supply horn and fans. if it passes, then refit the correct fuse and test again - keeping an eagle eye out for problems. The cable undergoes the ultimate test when the fans are operating and you operate the horn.

The key is why the previous owner modified your wiring, was it because wiring broke, or because the insulation has failed? It may even be just because one or more of the terminals is loose or otherwise making poor connection with it’s cable. Similarly, cables may begin to fail because several of the strands have broken – there may be continuity but high resistance when a large current is passed. Unfortunately the wiring in this area is subject to a lot of heat and is over 40 years old by now and accordingly brittle and/or work hardened – tread carefully!

Good Luck,

Regards,

[baganz.sven@web.de]

Hello Simon,

I tealls appreciate your detailed answer.

At the moment the fans get power directly over a switch in the cockpit, rewired with a new cable. The fan relay is not used

The horn relay is connected to the 50A fuse and works.

The + cable to the fan relay is just disconnected close to the horn relay (like you can see in the photo).
It is not broken and has connectiom to the fan relay.
So I will just connect it to the fuse.

Does on your car only one cable come out of the fuse or two?
Perhaps you can send me a pic from the fuse and the Connection of the fan cable connected to the fuse

Greetings from Germany
Sven

[vee12eman]

Hi Sven,

There is only one cable on the fuse holder - exactly as the wiring diagram shows, here is mine:



I can't get closer than that, but the cable just comes out of the loom then re-enters. I am not going to show you pictures of my fan relays which are significantly different to yours, as there are two of them, they have an extra, dedicated modern fuse and holder and connect to modern fans with different wire colours.

I am concerned that your system is somewhat compromised, possibly not even safe. Fan motors should be operated and controlled through relays, not the switch as you describe. There must be extra wires fitted, carrying fairly large currents down routes which may or may not be safe, i.e. they may become subject to chafing or other damage because they are not ideally routed. The relay is used to prevent a lot of this from happening, you now seem to have two cables carrying lots of current directly into the dash area and a switch of unknown origin to control them. From your description, the previous owner was a bit of a cowboy, or at least not knowledgeable in auto electrics and there is no knowing how safe the system is.

I STRONGLY urge you not to start re-making connections until you have investigated why the cables were bypassed in the first place. If you don't feel competent to conduct the tests described, take it to an auto electrician. I suspect that, expensive as the looms are, it would be cheaper to buy them and replace them yourself, learning in the process, as I think an auto electrician may suggest this anyway - it will be expensive for him to do it and doing it yourself will teach you a great deal - it's how I gained my knowledge.

It may be that the PO simply didn't understand relays, many don't, so bypassed them when they failed, I suspect you have connection problems (i.e. connectors not making good connection to their cables).You need to know why the changes were made in the first place before simply restoring connections - you may be lucky, but it's something of a gamble.

Regards,

[baganz.sven@web.de]

Hello Simon,

we are misunderstanding each other.
I know there are additional wires from + to the fans.
My pre owner has disconnected the fan relay and conected the fans directly to + via a Switch.

I can easily change this back.

The only Thing I'm lookin for is where the 2 + (brown) wires to the fan and horn relay meet als shown in the wiring diagram (see my attachment).
Where is this Point and how is the connection made?

The rest is OK. All wires are OK.
Only my pre owner has disconnected the wire which leads from the line fuse to the fan relay.

I'm just looking for the connection point and connection method.

Of course I will remove the unfused wiring in my car.

Best regards

Sven

[vee12eman]

Hi Sven,

In a previous post, I described a "branch", the diagram you posted shows the joint of this branch - the joint you have highlighted. As I said, it has been along time since I stripped and salvaged the looms, but I am fairly sure that the joint you are looking for is actually within the loom wrapping and is not one that you can connect and disconnect, rather it is a permanent connection (fairly unusual, but most looms have one or two somewhere), possibly soldered and the only way you will get to it is to cut the loom wrapping and inspect it. That is one of the reasons I suggested disconnecting it completely and doing continuity checks, to see if it has become detached/broken within the loom. You need to remove the fuse, disconnect the brown supply to the old fan relay and check continuity from the fuse holder to the fan relay end of the cable AND the (currently disconnected) brown cable near your horn relay. Note that the end of the fuse holder which is connected to the cable may not be the obvious one, so check both ends.

It is possible that this connection has failed and would explain all your problems, since it would prevent current from reaching either or both ends of the brown cable, i.e. the two relays in question. I think you need to establish the location of the problem - from what you have described I am fairly sure the problem will be with the length of cable between the fuse holder and the joint you have highlighted, or in this joint itself - it is a shame to cut the wrapping unless you have to, hence the continuity checks first (you MUST disconnect all ends of the cables in question first as the current can find alternative routes back and confuse the results). However, if necessary, then you can open up the loom, replace the cable or re-make the joint, then cover it using looming tape, as used on later looms - try to avoid using insulation tape which will eventually make a sticky mess and makes the loom very inflexible if used over any length, you will need it to finish off, but not for the whole length. I don't think we are talking a long length here, my guess is that the problem lies within a length of around 20 - 30 cm of the loom, so careful wrapping will not look out of place.

Again, hope this helps, I have tried to make it as clear as possible!

Oh, one last thing, the wiring loom in the knowledge base:

https://www.dropbox.com/s/a4ubnltt94dnq ... g.pdf?dl=1

is much clearer than the one in the manual and is the origin of the file I included in my first post. I think i was the one who provided it to David (Heuer) to upload in the first place.

Regards,

[Hugo]

I wouldn't run the fans directly from the switch - you will probably melt the switch or worse. You can get away with it on the horn, as that is only used very intermittently (although you may lose a bit of performance in terms of sound quality and loudness). But when those fans are on they're going to suck a lot of current.

[baganz.sven@web.de]

Hello Hugo,

that's exactly what I think.
I want to get rid of the mess my pre owner has created.
I will remove all the junk he has installed.
If I come to the conclusion that the original loom needs to be replaced I will use a new one from Autosparks.

Most of my time I try to find out what the pre owner has installed to "cure" problems.
(did I mention that the fuel pump is connected to the rear lamps!)
I can't believe what has been done with the car but I will bring it back to life!

Best regards
sven

[Hugo]

Interesting bit of wiring there with the fuel pump. You can have a bit of fun with wiring, for instance if you are looking for a ground wire with a meter, the feed to the brake lights (or any bulbs) will give you one. So you earth the fuel pump through the brake light wire, then every time you touch the brake pedal, the fuel pump cuts out (as the earth via the bulb filament now becomes a pos feed from the stop light switch). Pretty good anti-theft device! Or take the feed for the fuel pump from the tail light wire, then the car will only run with the lights on. Hmmm, what else can we do?

[baganz.sven@web.de]

Dear Forum colleagues,

this evening I spent some time with my dreamcar (to be) and have finally found all original wires.

The brown + cable on my photo is not the cable to the fans but the original one for the horn relay.
The connection is inside the loom (invisible without unwrapping) like Simon wrote (thanks!)

The original cable connected to the fuse has been cut and was lying hidden under the loom.

So if I remove the black wire on the photo, connect the brown one to the relay and then solder the cut one to the fuse everything is back to original. Of course I will check all wires again if something is broken and remove the mess my pre owner has installed.

Thanks also to the Autosparks helpline for quick response!

Taking your comments into consideration I have ordered a high efficiency aluminium radiator with modern fans and relays from SNG.
The switch will be the 75°C part from CoolCat.

I hope that my cat will finally stay cool under all conditions.

Thank you again for advice, I really appreciate that you all spend your time helping unexperienced newcomers like me.

Best regards

Sven

[vee12eman]

Hi again,

Glad to have been of help. Regarding the replacement fans/radiator from SNG, I suspect the setup will be similar to the one I fitted some time ago, although mine came from various sources. If the wiring does not come with the system, then consider the points in this thread:

viewtopic.php?f=6&t=9187&p=72761&hilit=fan#p72761

The thread shows a twin relay setup which I fitted to my modern fans. These tend to draw more current than the originals and the relay I had was not man enough for the job. It was a modern replica of the original Lucas design, but only worked once with the new fans, hence the redesign and use of modern relays - I think mine are Hella, from memory. They are hidden up beneath the cowl above the radiator and fan setup and I added a modern fuse in addition to the original on the engine frame discussed earlier in the thread.

Here is some more information from a previous thread, scroll down and you should find my posts with some photos which may help you fit your new set up.

viewtopic.php?f=6&t=3401&p=22726&hilit=fan#p22726

Hope this also helps,

Regards,