I disconnected Otter Switch wires several years ago during engine rebuild.
The 12v Blk/Red wire shows 12v all the time, the Black wire is ground, and test ok.
But there is a third wire (not colored) thick and shows no ground path nor battery voltage.
The single S1 fan is original and PO did not recall if it worked. It has two wires Green and Blk/Red) that are part of of wiring harness (pictured).
From schematics, its shows Otter Switching to Ground at a particular Header Tank Temp. Then why would the Blk/Red wire attach to the center otter switch?
Thanks,
Patrick
'66 FHC
PS: I searched the forum and can’t find an answer.
Have you checked to see if the two black/red wires (one at the otter switch, and the other at the fan) are one and the same wire? Just disconnect both ends and check the resistance between them using a multimeter on the ohms scale. The wiring diagram for your year of the car shows the black/red wire from the Otter connecting to a black wire (through an inline connector) which goes to the fan. The green and black/red wires in your last photo appear to have inline connectors on them, so from what you’ve presented everything appears stock. The wires that go to the fan motor itself should be green (plugs into connector with the green wire in photo 3) and black (plugs into the connector with black/red connector in photo 3). With it all connected up the black/red wire at the otter switch will show 12v until the otter switch closes. It is connected to the battery 12v via the green wire, motor coils, black, and black/red wires.
The two wires going to the fan are power and “otter”. This second wire goes to the otter switch center, and the other contact on the otter switch gets the ground connection. It’s a bit confusing because the otter switch controls ground, not power as you would expect. The otter isn’t polarized: the only reason that the fan wire goes to the center pole is that Jaguar expected the rubber isolators on the radiator and header tank would eventually fail.
Michael. My header tank rubbers are original and somehow the tank still sees ground.
David, yep, they’r the same blk / red, with the caveat that actual fan motor has blk and blk green, the latter two wires from fan motor go to an inline connect with blk to blk, and blk/grn to blk/red. I kid you not !
Which two wires should be connected to the tank’s double lug shown in pic ? And which wire goes to otter center lug ? I seem to recall disconnecting three wires at the tank.
Probably because they’re original and the rubber is failing on either the header tank or on the radiator (via the connecting brackets). Assuming the ground wire on the switch is removed, there should be no other path as both tanks float on rubber. Mine with fresh rubber buffers doesn’t see ground. At least it wasn’t, haven’t checked it lately.
I’m afraid that contradicts what you said in the first post, and what you show in the third photo! The harness to the fan has Green and Black/Red wires. If the fan motor has a Black and Black/Green (latter wire should be Green according to wiring diagram, but we can live with that), then how can the inline connectors go “blk to blk, and blk/grn to blk/red”! Where did the Green wire you referred to earlier go, and where did the extra Black come from? I’m guessing that what you meant to say was that the inline connectors go Black(motor) to Green(harness) and Black/Green(motor) to Black/Red (harness). If this is what you meant, then the connections should be reversed, but it probably doesn’t actually matter, as the fan motor (depending on it’s type) is probably not sensitive to which way round it is connected. I’d reverse the connections so you have Green(harness) to Black/Green(motor) and Black/Red(harness) to Black(motor) to be as close to the wiring diagram as possible. Also, the other end of the Black/Red wire should go to the center of the Otter for the reason Mike described. The black wire at the Otter switch should got to the outside terminal on the Otter. That extra wire floating around in the vicinity of the Otter switch could be anything…
I don’t know. Maybe they didn’t. Perhaps they fitted a single tang terminal, and a PO of your car added the double tang version - perhaps to ground that unknown wire you have floating about? Maybe someone who has a car of similar vintage to yours can comment on whether they have a double tang terminal or not, and if so, what the second tang is used for.
The double connector on the otter should be attached to ground. This piggyback isn’t factory, it was added at some point: probably you have some aftermarket equipment somewhere. The wire from the fan connects to the center, otherwise you will have a short due to your failing isolators.
This AM disconnected the rubber housed inline connector and directly battery tested fan motor; it works. Inline was actually correctly wired; green to blk / grn and blk / red to blk (motor).
Problem is the Otter switch fails to operate fan. If I short the two otter wires, would that action energize the fan ? But one of the two otter switch wires shows 12v battery (with ignition key on) and second otter wires shows ground.
It sounds like your otter switch is bad unless your fluid level is very low. You can easily test it by pulling it off and immersing it in hot water with a thermometer and checking for continuity at the right temp. I’m not sure what the spec is but I’d expect something around 90c. If it’s bad I suggest the one Mike sells, then you’ll never have to worry about it again.
Again, the otter switch controls ground. So one wire will be ground, the other will be about 12V, a little less than battery, coming all the way through the motor. If you short them together the fan will come on.
You probably have a bad otter switch. You should add a relay when you replace it, or the new switch won’t last long.
That must explain the double lug ground; PO must have had fan running full duty. PO (in early 80s) had several incidents of blown head gasket and renewed head gasket replacements at local mech, but alas at some point the head was damaged from frequent Raleigh NC overheating and punctured hole in head’s coolant passage, dumping coolant into piston bores. Seized engine (rusted pistons + bores) when I bought it (but no block cracks). I had new top hat style liners installed and CW welded repaired the head. Now it idles fine (Florida) for about 15min and temp gauge reaches 75 (no fan action) and soon signs of boiling (I switched engine off).
Mine has a baffle about an inch below the spout. I keep it filled to just above the level of that baffle, just enough to wet my finger tip. I don’t get any overflow at that level.
