A simple one, perhaps...

My '76 4/4 has a Kenlowe fan fitted. The relay is playing up, so the fan runs a lot of the time (unless going over a bump makes the relay drop out... Another bump usually brings it back on though!).
There is a mnaual switch under the dash, which works, so I plan to do away with the relay for the present (or perhaps permanently, just relying on the good old switch and observance of the temp gauge...

Many years ago I fitted virtually the same Kenlowe (has a temp sensor on a long copper tube which fits into the radiator top hose) to my MGB, but I suspect the paperwork (and wiring diagram) went with the car when I sold it. Can anyone remember whether switch/relay were wired in parallel, or whether the switch also controlled the relay to power the fan?

I don't want to drive to Derbyshire on Saturday and Gurston on Sunday with the fan permanently running...

Cheers,

Graham, the sensor relay and the switch work independently. If you should need the paperwork and wiring diagram I can try to find them in my rubbish and send you a scan.

A long time ago I did away with the sensor and the tube (the relay is still there) because the rubber "bridge" for entering the tube into the hose started to leak. New Kenlowes have the sensor on the outside of the radiator, taking the temperature by contact with the metal. I would prefer that but am in doubt that they will sell it separately.

BTW there was also a "flying fuse" in the set.

Frank

Thanks Frank.
I'll get my test meter out tonight and pull the relay connections. If you do come across the paperwork a scanned copy would be appreciated, but there is no hurry!

Meanwhile, I'll checkout Kenlowe for a newer temp sensor/relay setup...

Cheers,

Just fit a new relay and switch through that - easily done through earth. EG piggy back both live feeds from the single supply - then accessory supply to fan - earth from relay to switch to earth.

That was the plan if the switch controlled the relay Dave.
However, it would appear not. I'll check tonight before heading to the local radio club meet. The Kenlowe switch seems pretty robust.
Having looked at their web site, they are still doing sensor in top hose, so might see if they'll sell sensor/relay without all the rest of the kit - for when I forget to look at the temp gauge!

Please may I piggyback on this as I'd like to add a manual over-ride switch into my OTTER switch circuit before we go touring in France later in the summer. I know it's just a simple jumper across the two contact points, and I'd like to put an in-line warning light alongside the switch (to remind me I've forgotten to turn it off!) but should I add a relay into that circuit and if so, how? I'm inclined to instal a relay if sensible just to keep hot wires away from the cab
Answers on KISS principle please; never quite grasped all this electricity stuff at school. Many thanks

When you say "Otter" do you mean the brand as fitted to the Rover V8? If so, all the Otters I've seen have one terminal. If you earth that terminal the fans will run. So you can piggy back from that terminal to a switch and then to earth. A tidier solution though is to trace the Otter lead back to the relay (on MGBV8's the wire is black with an orange trace from memory). Then piggy back from the relay terminal which goes to the Otter - via a switch to earth. In this situation a second relay isn't necessary. Fitting a warning light on an earth switch is not simple - you'd at least have to run a live feed from the fusebox to the lamp and then to the switch. I suggest you seek help with that, to avoid red hot and melting wires, which is no fun at all.

Kenlowe: Relay is two wire and on the earth side of the fan motor (at least that's how RTA is wired!).
So, disconnected the lead from relay to earth leaving the other wire, going to the motor, in place. Switch works, it's just the driver who forgets to switch things on

Cheers,

There's a thread on the GoMog site at http://www.gomog.com/allmorgan/bypass.html
which I was going to follow as looks reasonably IdiotProof, but then I spotted "fit a relay" and began to panic
This suggests that the Otter switch can be "jumped" by switching separately across the power in and out terminals, so I was thinking of doing just that but adding an in-line warning light as well. And then I thought, relay, but still not sure where to start, so this thread is still open for further thoughts please

Which model (of Morgan)?
Now for the silly question - have you a circuit/wiring diagram?
Are you anywhere near Gloucestershire?

Cheers,

Killer question Graham; No, I don't have an accurate wiring diagram for a 1988 +8 efi - does anyone?

The only one I've found on the web (again, the GoMog site) is generic and suggests that the Otter switch is breaking the earth wires, but without testing yet, my own fitting looks ominously like one black and one red, and red usually implies Hot!

Red.
Yes, but the switch could still be on the earth side of the relay. You'll have to get the test meter (or lamp) out I'm afraid...

Cheers,

So are you suggesting Graham that both leads could be "dead" (as in Not Live)and that jumping across the terminals on the Otter (and/or introducing a switch) will complete the earth circuit, energise the relay and start the fan ...?

No, not at all.
If the switch is open (i.e. drawing no current) then the 'hot' side will be at a nominal +12V, regardless of whether it is on the live or earth side of the relay coil.

'Fraid I'm not much good at trying to draw things on a PC (pencil & paper works best for me every day ), but in the simplest form of the fan control circuit, imagine a wire from the +12V side going to the relay coil. From the other end of the relay coil another wire goes to the 'hot' side of your otter switch. The remaining wire from your otter switch goes to earth.

The alternative is for the +12V to go to your otter switch, then from the switch to the relay coil, thence from other end of relay coil to earth.

Normally, if the switch is used to switch to earth it would have only one terminal, the earth connection provided by the switch body where it is fitted into the radiator - but this isn't always the case.

Before you can fit a manual switch you need to know in which order the relay and switch are wired. Probably easiest to do by pulling the fuse and measuring with an ohm meter what connects to where. My guess is the relay is probably hidden behind the dash, which makes things a trifle more difficult...

Cheers,
Graham

Thanks Graham, I can't wait to start poking around with a test-light and a fire extinguisher
Hopefully I will advise more in the morning ...

Good luck!

Further note, if you are using a test light:
If the 'earth' side of the otter swich goes up to 12V when the switch is on, the switch is on the +12V side of the the relay coil.
If the 'hot' side goes down to 0V (light goes out) when the switch activates, the relay is on the +12V side of the relay.

HTH

Sorry Graham but when I said test light, that's what i meant, so the result is, test light stuck onto red wire and earth, light comes on (hot); same light onto black (with orange tracer) - No Glow
So now I have power and earth to and from Otter (makes sense?) and absolutely no sign of a relay with similar leads (all wires just head into or out of general loom)dare I add a switch and warning light into that circuit, should it be fused in any way, and other advice??
Thanks for being there - John

OK John,

Do the earth side test with the engine hot, so the fan is running.

If you have 12V on the earth side when the fan is on then the otter switch is on the +12V side of the relay (or fan if there is no relay). This would agree with the wiring colour code (see below).

If that is the case you could connect a manual switch across the otter switch connections. Also makes fitting an illuminated switch easier.

I'd suggest a reasonable quality switch - if there is no relay then the cheap switches won't cope with the current for very long.

Under BS-AU7a wiring codes (vintage 1983 ) black with an orange tracer is "radiator fan motor to thermal switch". However, this may still go via a relay. If you are going to tap across the otter switch itself, then the circuit fuse will be sufficient, however, if you plan to take +12V from another source to the switch, down to the black/orange wire then fit an extra fuse. Also, keep the same colour codes as you presently have - it makes fault tracing years later somewhat easier!

I use Vehicle Wiring Products (a Google search will find them) for most of my electrical supplies.

Cheers,

Brilliant Graham - next stage is going to have to wait for a few days as there are domestic jobs required this weekend, but I now have a plan ...
again, kind regards
John

OK Graham, I'm "working from home" today (and it looks like rain in Scotland) so had another chance to get out and get under, and now I need your advice again please. Remember, no electrical skill, just a fused jump-wire and a test light, certainly nothing with numbers or other displays!
Test light attached to red wire and touching earth, light comes on!
Jump red wire to Black+Yellow, fan starts (good) and test light now goes OUT
Therefore presumably this Otter is an earth switch, but I'm out of my depth already
So if I want just to switch the fan on manually, I bring a wire from each of the otter terminals up to the new switch and Bingo!
But how can I add a warning light at the switch end? Presumably it will need an independent, fused power feed, permanently on, then I link in the earth from the switch - does that make sense? Presumably I fit the warning-light earth onto the earth (BY) side of the otter, rather tha the red, otherwise I would have HOT wires on both sides of the warning laigh - told you I was getting confused!
And now, if the fan is switched on manually, what happens if the Otter is open too?
There is what appears to be a wiring diagram on the GoMog site but the wire colours don't fit as show BY into otter and B out, whereas I seem to have R in and BY out, see http://www.gomog.com/allmorgan/wiring88&89.gif
many thanks in nervous anticipation
John

Interesting. Your wire colours do not appear to match your wiring. You can as you suggest jump the otter switch. Wiring a warning light is now more complicated, but you have the right idea.

I don't suppose you can see the wires where they enter the fan motor?

Cheers,
Graham

yes I casn see them going into the fan Graham, but they both look black! Any guidance on which side to fit the warning light?
thanks, nervously, John

Now traced back further to bullet-junctions, and the answer is ...
one Purple, t'other, Black & Yellow going into fan, which is consistent with the wiring diagram on GoMog site
Any chance this is just another Morgan anomaly?
bw - John

Hehe,

Sorry. You need 'hot' wires both sides of the warning lamp - that way it will be off when the switch is off and on when the switch is on. However, it will also come on when the otter switch switches on (just as my Kenlowe does).

So, fused supply to lamp (small fuse if it's only protecting a lamp or LED). Other side of lamp to 'red' of otter switch (or its extension lead to the switch on your dashboard).

Both wires into your fan are black? Not one being black/yellow?

Have to admit, I'd rather do this myself, than at a distance! Any JockMog members near you with some electrical experience?

Cheers,

If you look in the Demontweeks catalogue (page 251 - Part No. sw4005)£8.50 - Illuminated Fan switch. You can get a rocker switch in the correct style to match what you already have and will give you the inputs requried to install.

Have Fun

Thanks Graham, red on red then! If you look at my second reply earlier thisd morning you will see that I found the wires into the fan unit itself are (just like the diagram) Purple and Black&Yellow
As for switches, I want to put a waterproof switch on RH side, at bottome of dash panel so well away from knees, and Vehicle Wiring Products can pair that up with a round amber light c/w Fan symbol!!
Now I need to add an in-line fuse holder to my list and I think I'm almost there ...
Working from home is so productive, I always find - anyone for tennis?
regards all - John

Latest development - plan A didn't quite work as I could either get warning light OR fan on, but not both. So now reverting to a 2-pole switch with entirely separate 12v feed & earth circuit for warning lamp. Watch this space

Hmm, sounds like there is a relay in there then.

Isolating the warning/indication circuit is a good idea anyway.

Cheers,
Graham
(Just back from Snowdonia - by Z3 unfortunately - SWMBO worried about the rain!)