Red fan light

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Coffeedan
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Red fan light

Post by Coffeedan » 03/12/17 15:03

Hello so day one problem one

So start with 1993 2l gt t-bar

Driving home last night noticed that the red fan light come on
After a little reading on a few Google searches I'm of the understanding this relates to the fan in the engine lid (please correct if wrong)
So a little prodding about i can see that this fan has been modified I'm guessing to get away without fixing the problem,
Underneath the fod switches there is another switch added this controls the fan on off but only works when the front lights are on bit of a bodge job as well twisted wires instead of connections

So my thinking rewire the fan correctly and I'm expecting the fan to run permently
Then try and diagnose the part thatthats failed
Which from my searches tell me it will be the temp sensor or the control unit

Three questions
1) am I on the right track
2) why would anyone add a switch instead of fixing the problem
3) does anybody have the part numbers and wiring diagram

Thanks in advance for helping

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jimi
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Re: Red fan light

Post by jimi » 03/12/17 17:39

I'd say your on the right track. Look on this thread for wiring diagrams http://www.mr2oc.co.uk/forums/198/80372.html also look in the Downloads section (link at the top of the page next to the Gallery)
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MR2DI4
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Re: Red fan light

Post by MR2DI4 » 03/12/17 19:37

The fan ECU has to see a load, i.e the fan in the circuit and if the current goes outside a range the light comes on. Typically the fan still would not run if you unplugged the hood sensor because the fan has gone open circuit.

I replaced the fan with a power steering relay so I could also switch in the hood fan at the same time. The power steering relay coil draws 1.5A so this was still seen as a "Fan" by the ECU so the light remained off on the dash.

The PS relay is good for like 60A or more so it was ideal for turning on two fans in the engine bay.

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jimi
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Re: Red fan light

Post by jimi » 03/12/17 21:43

MR2DI4 wrote:
03/12/17 19:37
Typically the fan still would not run if you unplugged the hood sensor because the fan has gone open circuit.
Or an O/C on the wiring to the fan motor or the Cooling Fan Computer has failed (from memory I've probably seen more fan controller failures than motor failures on MK2's)
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Re: Red fan light

Post by MR2DI4 » 04/12/17 3:54

Yes its possible the fan ECU has failed. All the electronics is now getting pretty old. The ECU would be a straight forward fix for someone with an electronics background.

I would be checking the wiring and making sure the fan has a decent earth connection before blaming the ECU.

Fan is easy to test, pull the connector and put a 12V battery on it.

If the hood sensor is unplugged then don't expect the fan to last that long, the brushes will wear out on it and it will stop. Even the decent SPAL fans only last a few thousand hours of run time, thats why you either boost or temperature control them or both so they only come on when needed, plus it draws about 4.5A from memory so you don't want it running full time.

Coffeedan
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Re: Red fan light

Post by Coffeedan » 05/12/17 9:37

Thanks for the replies ill be taking a proper look this weekend
What I am sure of so far is the fan is not at fault
Now it's just working backwards to see where the problem lies

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Re: Red fan light

Post by TonyleFrog » 05/12/17 18:16

MR2DI4 wrote:
04/12/17 3:54
Even the decent SPAL fans only last a few thousand hours of run time, thats why you either boost or temperature control them or both so they only come on when needed, plus it draws about 4.5A from memory so you don't want it running full time.
The largest automotive SPAL fan available with that current rating is 190mm (7.5") diameter.
Go any bigger and you're looking at an uplift of between 1 and 3A.
http://www.spalautomotive.com/eng/produ ... al_12.aspx
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