Fan fuse alarm- How to fit.

A cause of overheating in traffic is the radiator fuse fan blowing when the fan is triggered.
The first thing you can do is replace the 15amp fuse with a 20 amp. This usually overcomes the problem of the initial switch on of a sticky fan blowing the 15 amp fuse. MGR modified the fuse in this way in later models.

How can you know that the fuse hasn't blown leaving you open to engine overheats?

Dieter has fitted a small 12v buzzer to the circuit that sounds if the fuse blows.

This is his HOW TO.

You will need:-

- 12V buzzer with black and red wires
- crimp sleeve M4? (check bolt size be4 you buy, could be M5
- Y- connector

Disconnect the Battery to make safe.
Unclip the upper cover of the front(underbonnet) fuse panel



Remove the inner cover



to reveal the securing screws



Unbolt the fuse box.(2x 8mm or 10mm bolts)



Unclip the lower cover to reveal the wiring harness.

Locate the hole in fuse panel (see red arrrow) and lead the black (-) buzzer wire through the hole (from top to bottom.)

Locate brown wire at Fuse # F2 from below (blue arrow) and connect the black buzzer wire to it with a Y-Connector. OR Strip back some insulation and solder the black wire to the brown fuse wire. Use shrink insulation to tidy it up.
Lengthen the black wire if it's too short.
Close lower cover. Take care not to trap the black wire.
Place buzzer into fuse panel
Bolt panel back in place
Remove the hex-screw at the fusebox positive connection.
Crimp sleeve connector to red wire and bolt red wire with sleeve to the positive connection.


Reconnect battery, synchronize alarm blipper by pressing one button 3-4 times.

To Test the alarm:

Switch the ignition on and run engine until the front fan activates.
The buzzer should not sound. If the Buzzer sounds or the fan doesn't operate as expected ... check your wiring and whether F2 fuse is blown
Now pull fuse F2.
---->Buzzer should sound :woohoo:
Replace Fuse F2
<---Buzzer should be silent. :woohoo:

If the Buzzer continues to sound ... check whether F2 fuse is blown

While we're talking about fan operation:-

The engine bay fan may not operating. To test it, disconnect the plug from the Ambient Air Temperature sensor here, with the engine running. The fan should operate. If not check the fuse.

Just a small addendum to the test procedure.

I fitted my alarm today and tested it as Dieter suggests.

To Test the alarm:

Switch the ignition on.
The buzzer should not sound. If the Buzzer sounds ... check your wiring and whether F2 fuse is blown
Now pull fuse F2.
---->Buzzer should sound
Replace Fuse F2
<---Buzzer should be silent.

If the Buzzer continues to sound ... check whether F2 fuse is blown

However, with the Mk2 F I found that the buzzer will not sound using the above technique, leading to much head scratching.

In fact with the mk2, the fan also needs to be running before removing the fuse elicits a buzzing response. :yesnod: :thumbsup:

David,

thanks for testing. That's my fault in the description. :sick:
There's no difference between MK1 and MK2 :whistle:
So valid for all. Buzzer sounds only when the fan line is activated _and_ the fuse is blown.

Dieter wrote: David,

thanks for testing. That's my fault in the description. :sick:
There's no difference between MK1 and MK2 :whistle:
So valid for all. Buzzer sounds only when the fan line is activated _and_ the fuse is blown.

Thanks Dieter, I'll amend the test procedure in the main post. :thumbsup:

My engine bay fan may not be operating. To test it, I need to disconnect the plug from the Ambient Air Temperature sensor. How does this disconnect and must the engine be running when I disconnect it?

Cheers

Leigh Ping wrote:
My engine bay fan may not be operating. To test it, I need to disconnect the plug from the Ambient Air Temperature sensor. How does this disconnect and must the engine be running when I disconnect it?

Cheers

Pop off the little metal clip (don't let it fly off and get lost!) and then slide the connector off - voila!

David Aiketgate added:

The easy way is to push the wire clip into the plug, this disengages the lock allowing you to pull the plug off

Thanks Adam & David. That clip's pretty tricky to catch when it springs out. The fan was working fine, but it's efficiently quiet for an engine fan. Probably why I've never heard it until now.

Anyway, to test the fan, I first unclipped the metal 'spring clip' shown in the picture above (engine off). I left the plug on and started the engine, then pulled the plug off. The fan then came on.

What's a Y connector ? Could I use a piggy back spade connector to splice the black wire ? This is the next thing on my mod list after the overheating incident recently

Y connector gives you two connections from one, so a piggy back spade would do the job.

Thanks David. Never heard of them before that's all.

A heat-shrinkable butt crimp would do the job, but my preferred method (as on any car electrical job) would be to solder and heat-shrink, by far safer and much more reliable.

DZ

Agree. That's what I did in the end. Soldered and heat shrink is also a neater job and requires less space. :yesnod:
The Y connector is part of Dieter's original how to.