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PRC4427 Voltage Sensitive switch


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#1 Maverik

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Posted 21 October 2013 - 02:40 PM

Another mystery to me while stripping the 89, LR110.

 

There was the big yellow relay PRC4427 floating around behind the dials when I took it apart, there are a lot of fine brown/black wires going into the relay base.

 

Can anyone tell me what the relay was for?

 

I thought you only needed them in a split charge system, said vehicle has only one set of battery cables and no other signs of a split charge system...

 

Mav


C Reg 1986 LR90 with Defender 200Tdi Conversion Build thread here.  

P Reg 1997 Disco 1 (Camel),   M Reg 1995 Disco 1,                            P Reg 1996 Disco 1 (Spares),  

F Reg 1989 110 (Spares),        H Reg 1991 110 (Fergal the Camel),   F Reg 1989 110 Hi Cap (Steve)


#2 ChrisB

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Posted 21 October 2013 - 03:39 PM

Often also used for rear window demisting so it's only on when the engine is running and battery is not low.
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#3 western

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Posted 21 October 2013 - 04:47 PM

as above it's to stop the rear screen heater being switched on & draining the battery when engine is of & alternator is not charging, if you look in the right corner there should be a metal tab for the VSS to fit on to, it's sits next to the rear screen heater relay.


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#4 Tanuki

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Posted 21 October 2013 - 05:05 PM

Sometimes also used (as an alternative to a timer on the principle that "I've got this so I don't need to buy a timer") when retro-fitting a heated windscreen and/or heated mirrors.



#5 western

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Posted 21 October 2013 - 06:12 PM

& it's also used on some models with lights above the screen as a can't be switched on if engine is not running. to protect the battery from being flattened


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#6 Maverik

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Posted 22 October 2013 - 07:45 AM

Thanks guys, I think this might have solved the mystery of some empty relay holders on the 110 too...


C Reg 1986 LR90 with Defender 200Tdi Conversion Build thread here.  

P Reg 1997 Disco 1 (Camel),   M Reg 1995 Disco 1,                            P Reg 1996 Disco 1 (Spares),  

F Reg 1989 110 (Spares),        H Reg 1991 110 (Fergal the Camel),   F Reg 1989 110 Hi Cap (Steve)





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