Main wiring loom regulation

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Chillipepper

Chillipepper

Member
Posts
12
Location
Telford
Guys
So I have a 1991 110 ex MOD defender 2.5 NA diesel
Issue I seems to be having is with the gauges especially water temp gauge - always reading hot hot hot but I have tested engine with infrared temp gun and it runnin just fine at about 73/74 degs have had the thermostat out and tested it and it is fine fully opens at 74 degs - tested gauge and it fine gauge is a PRC7113
I have replaced sensor, run new wire from sensor to gauge - still the same hot
Read somewhere that it could be an issue with alternator - have tested that and it is puttin out 14.2v - however, with engine running when I check voltage anywhere in main wiring loom and to gauges I get the same voltage of 14.2v - I added a voltage regulator between power supply to gauge and this had some effect now only just in red
I was under the impression that the main wiring loom should only be 12v
Any ideas apart from replace with VDO
Cheers
 
Chillipepper said:
Guys
So I have a 1991 110 ex MOD defender 2.5 NA diesel
Issue I seems to be having is with the gauges especially water temp gauge - always reading hot hot hot but I have tested engine with infrared temp gun and it runnin just fine at about 73/74 degs have had the thermostat out and tested it and it is fine fully opens at 74 degs - tested gauge and it fine gauge is a PRC7113
I have replaced sensor, run new wire from sensor to gauge - still the same hot
Read somewhere that it could be an issue with alternator - have tested that and it is puttin out 14.2v - however, with engine running when I check voltage anywhere in main wiring loom and to gauges I get the same voltage of 14.2v - I added a voltage regulator between power supply to gauge and this had some effect now only just in red
I was under the impression that the main wiring loom should only be 12v
Any ideas apart from replace with VDO
Cheers
Click to expand...

The main wiring loom should be whatever the battery is, and that should be whatever the alternator is outputting. I think some early vehicles did have a voltage regulator behind the binnacle, but don’t know which ones.

Are you sure the sensor and gauge are compatible? Some gauges read hot when coupled to the wrong sensor.
 
Just googled the part number for the gauge, PRC7113, and it didn’t bring anything up. Are you sure that’s the part number?
 
Here is the gauge -sorry it should have been PRC7311- it is pair up with the sensor - PRC2505 ( with black top)
 

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Chillipepper said:
Here is the gauge -sorry it should have been PRC7311- it is pair up with the sensor - PRC2505 ( with black top)
Click to expand...

From what I can tell, PRC7311 is referring to a temp gauge fitted to 200tdi models (at least that’s the part number that was fitted to mine as an original). If that’s the case, the sender is the wrong one. PRC8593 is for the 200tdi sender.
 
Ok so replaced sensor with PRC6663 after a quick chat with Bearmach - still goes into red - will try as suggested above and let ya know results
 
Im sure I had the exact same problem with mine, its on here somewhere on one of my threads with part numbers. will try and find it,
I had to get a different gauge and it solved problem. Ive got the other still somewhere, if its the one you need give me a shout and I will check the part number on it.
 
border said:
Im sure I had the exact same problem with mine, its on here somewhere on one of my threads with part numbers. will try and find it,
I had to get a different gauge and it solved problem. Ive got the other still somewhere, if its the one you need give me a shout and I will check the part number on it.
Click to expand...

What engine did you put in yours? Was it a 300TDi discovery? If so, that will have been the issue. The discovery temp sender won’t work a defender gauge.
 
mick 1986 said:
What engine did you put in yours? Was it a 300TDi discovery? If so, that will have been the issue. The discovery temp sender won’t work a defender gauge.
Click to expand...
Yes Mick disco 300tdi in to what was 2.5 na. I remember I had to change from what ever was originally in as was reading hot all the time. think I had to change sender to.
 
So I have now tried sensor PRC8593 - it is alittle better as it does not head right of the scale in hot however it's still not right - with IR gun engine is at 73degs which is fine - next step is new gauge so Border yeah if you could send part number that would be great- very strange tho as old gauge tests fine ??
 
So new gauge ordered will arrive tomorrow -
Have replace the earth lead from engine to chassis but will go through the process of cleaning and reattaching the battery to chassis connection - I will run new wires from battery negative to gauge as earth, a new wire from sensor to gauge and new wire from positive on battery with 5amp in line fuse and see whats what
If all the above fails then Durite is the route - would have liked to keep it all original but if it gona be this troublesome then.........
Still would like to know what the issue is and if I can figure it out it may stop someone else from pulling their hair out over this
 
New gauge now fitted and it is working, however, it is now showing slightly on the cold side - bizarre - as I have the 2.5na diesel which according to the 'book' should be running at 73degs - it has a thermostat for this temp - guess I can live with it although would have liked the gauge to be sitting at the 12 oclock position - guess it maybe be a case of playing around with different senders ??
 
it got a 73 deg thermo in it - which is supposed to be correct - got a few sensors to play with as would like it in the 12 o'clock position - will keep trying -
 
That’s to cool isn’t it, that’s for hot climate use, the standard one was an 82degree IIRC and that’s what I had fitted in mine, all year round in the UK with no issues. 74 is to low for our temperate climate.

4C5D1CE0-A1C3-49F7-AD60-119BB285B036.png

I would fit an 82 degree, and check that the system is pressurising correctly

what gauge and sensor did you fit? They need to be a matched pair, you can’t just chop and change sensors to get the gauge to say what you want it to say.

If they are a matched pair then they are indicating the actual engine temp,

post photos of your gauge
 
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