Hymer 544 wiring issue.... Puzzled (1 Viewer)

navininika

Free Member
Mar 7, 2015
3
1
Fleet
Funster No
35,358
MH
A Class Hymer B544
Exp
Newbie
Please Help....

We have just bought our first motorhome, a 1994 B544 Hymer. We have steadily been cleaning her over the weekend and testing various bits, elec hookup, kitchen tap, lights etc. Pleased to say that all is working apart from the most frustrating problem and we're hoping someone with a bit more experience will be able to help us.

With the 12v system on, water tank full the kitchen tap operates fine. You can hear the microswitch activate the pump and water appears as it should. The same applies to the electric flush on the thetford loo. However as soon as we try to operate the bathroom tap it trips the fuse (5amp labeled pump on the electro Bloc)

Now when we got the van, the leads from the bathroom tap were disconnected. I studied the wiring diagram and translated the german to see what should be what and I connected the wires to what appears to be the same connectors for the kitchen tap? It blows a fuse straight away, indicating what I think should be a short, but when this tap is disconnected all other items work fine.

I then believed that the tap may be faulty, so have purchased a new tap with microswitch. Have replaced said tap this afternoon and yet again it just blows the fuse when connected and turned on.

I am totally stumped, pump works fine, kitchen tap works fine, toilet flush works fine but as soon as I connect the two leads from the bathroom tap I am back at square one again. I can't understand where it might be shorting.

If anyone can help us, it would be greatly appreciated we were hoping to go on our first weekend trip this weekend and feeling totally deflated :(:cry:
 

hilldweller

LIFE MEMBER
Dec 5, 2008
605
36,109
Macclesfield
Funster No
5,089
MH
Zilch Mk1
Exp
From Aug 2007
The wire from the tap to the pump relay is cut and shorted to ground somewhere. Worst case is abandon it and route another wire from one of the other taps.
 
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navininika

Free Member
Mar 7, 2015
3
1
Fleet
Funster No
35,358
MH
A Class Hymer B544
Exp
Newbie
Hi Brian,

Thank you for your speedy response.
The wiring is a bit confusing, there must be a loop going somewhere, as the connections into the block under the sink can stop the kitchen tap working if I disconnect one of the connections. Thats what is confusing me, surely it would short out when the kitchen tap is used. I'm going to try and get an image of the connector block and post it.

Thanks Ivan
 

Lenny HB

LIFE MEMBER
Oct 18, 2007
54,132
152,832
On the coast in West Sussex
Funster No
658
MH
Hymer B678 DL
Exp
Since 2008 & many years tugging
I just wondering if the previous owner changed the micro switch & put new wires (they break inside Reich taps) in but didn't have a clue and connect the feed back to the pump to earth, so when you turn the tap on it shorts out the supply.
If you can measured 12 volts across the micro switch that would be the answer.
 

JeanLuc

Free Member
Nov 17, 2008
3,304
2,199
Warwickshire
Funster No
4,952
MH
Hymer B630 Star-Line
Exp
Since 2007
Be aware that Hymer do not use the same wiring colour coding that we are used to. Normally, in a Hymer, blue is positive and brown is negative for 12V DC circuits.

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Lenny HB

LIFE MEMBER
Oct 18, 2007
54,132
152,832
On the coast in West Sussex
Funster No
658
MH
Hymer B678 DL
Exp
Since 2008 & many years tugging
Be aware that Hymer do not use the same wiring colour coding that we are used to. Normally, in a Hymer, blue is positive and brown is negative for 12V DC circuits.
Blue for positive has been standard in Caravans & Motorhomes since the early 80's with either brown or white for earth. My Hymer has some strange variations depending on the loom never take any wiring for granted in a Motorhome.
 
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OP
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navininika

Free Member
Mar 7, 2015
3
1
Fleet
Funster No
35,358
MH
A Class Hymer B544
Exp
Newbie
Thank you all for your input and thoughts. I managed to get some panelling out and isolate wire pairs one by one. I then noticed some bare wiring that must of been shorting like hilldweller mentioned.

Wiring colours were ok I think as blue was positive where I was testing.
Connected the tap again and thankfully no fuses blown. I can't confidently say what I had done to fix it but I guess the bare wire and reattaching the pairs to the block all played a part.

Just happy it is sorted.
Thank you all again
 

Tootles

Funster
Deceased RIP
Sep 14, 2013
9,511
34,800
Lancaster
Funster No
28,093
MH
Coachbuilt
Exp
Was a newbie, now a Middie.
If you ever need a live feed to the bathroom taps, you can find a connector set behind the trim on the top right, over the sink mirror. That feed also supplies the strip light along the side of the habitation area, beyond the bathroom wall. (y)
 

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