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Old 9th February 2020, 12:35   #1
Alan_M
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Default FBH tests Ok but not working

I have been through the test procedure by earthing pin 3. Doing this the FBH fires up and runs for as long as the earth to pin 3 is maintained and will heat the coolant producing plenty of heat.
But in the cold mornings last week (around 0 degrees) it didn’t appear to be coming on. I stopped after about a mile or 2 to check and it definitely wasn’t working.
I’ve checked again by spraying temp sensor to bring the displayed temp on the dash down to -3 and again the FBH didn’t start when I started the engine which was cold.

I assume it’s not getting a signal to switch on, or could there be a fault within the FBH.

Any ideas what the problem might be and what I can I check/test to try and sort this please?
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Old 9th February 2020, 15:23   #2
bl52krz
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Perhaps the temp sensor has packed up. Drop Trebor or Devilish a private message. They are the guru’s on this equipment.
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Old 9th February 2020, 17:17   #3
Alan_M
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Quote:
Originally Posted by bl52krz View Post
Perhaps the temp sensor has packed up. Drop Trebor or Devilish a private message. They are the guru’s on this equipment.
Thanks, will send a pm.

The dash temp reads correctly from the sensor behind the number and the coolant temperature is working correctly - is there another temp sensor somewhere?
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Old 9th February 2020, 17:33   #4
75driver
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Default FBH tests Ok but not working

Yes, there’s another sensor visible through the front grille, on the drivers side. It’s mounting bracket is attached to the ac pipe work from memory.

Here it is, if link works.🙄

https://images.app.goo.gl/qF4SRgQwDWmSoWwDA


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Last edited by 75driver; 9th February 2020 at 17:36..
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Old 9th February 2020, 17:56   #5
David Lawrence
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That sensor has a tendency to short out against the metalwork behind the grill and the wire goes open circuit. Sensor itself is probably fine but you will find a broken wire coming from it. Just a guess but worth a look, will just need a new bit of wire splicing in if so.
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Old 9th February 2020, 18:01   #6
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Hello there.
Check the wires from the sensor behind the front bumper, mine had rubbed about 4 inches back from the sensor,bumper off job really.


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Dave beat me to it!!!!!

Last edited by Kev75; 9th February 2020 at 18:21.. Reason: Up date
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Old 9th February 2020, 18:08   #7
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for my own learning curve could I ask, would shorting out the wires together to the sensor behind the bumper, make the fbh start?

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Old 9th February 2020, 18:51   #8
Alan_M
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Thanks. Sounds like a good starting point. I didn’t realise there are 2 temp sensors behind the bumper.
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