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Joined: Apr 2010
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nortj Offline OP
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Has anyone come up with a simple solution to wiring in a warning light that indicates that the electric fan is running?
There was a thread some time back headed Kenlow that touched on the issue but didn't have a solution. My +4 is a 1996 T16 that does not include a relay in the fan circuit.
Maybe if I wire in a relay I could pick up a feed for the warning light.

Jon

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It depends how the fan is wired. If there's no relay then there may be a thermo switch in the radiator header tank. Late MGB's were activated this way, so there are two wires - live in to the thermo switch, and switch to fan from it. A wire from the switch to fan wire to a light, then to earth would work on this system.
Where a relay is fitted it's usually activated by the earth wire through a thermo switch, (Otter type)so a single wire is used. All this needs is an ignition switched live feed to a lamp with a second wire connected to the single earth wire to the thermo switch. Use a multimeter to find out how it's wired first, and be careful. It's very easy to blow fuses without much effort.


DaveW
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'16 Yellow (Not the only) Narrow AR GDI Plus 4
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nortj Offline OP
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No relay on this 1996 model. The live feed goes to the fan motor and then to one side of the radiator thrmo switch. The other side of the switch goes is wired to negative.
When the switch closes the fan motor is grounded and fires up.
Looking at the appropriate wiring diagram in Gomog, the wiring is correct on the car.

There is quite a load across these contacts so maybe rewiring via a relay would be more reliable.

As there is always a positive supply to the fan motor and to one side of the switch I can't fathom out how to wire in a warning light just to bring attention to the fact that the coolant is hot enough to require the fan to run.
I thought it quite a good method of monitoring any potential overheating situation

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My T16 +4 rarely gets warm enough for the fan to kick in & when it does at idle you can hear it.

Isn't that enough given the temp gauge as well?


JohnV6
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nortj Offline OP
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As the temp gauge is over on the left of the dash, the gauge is partially hidden when you have half the tonneau zipped up. Agreed, you can hear the fan at idle but not above that.
A warning light to indicate the fan was running would bring your attention to the gauge and monitor any possible overheating.
As I intend to take the car to Portugal this year there it will be running in higher ambient temperatures.

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If you add a relay you could have 2 feeds and a light.


JohnV6
2022 CX Plus Four
2025 MG ZS EV aka Trigger

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