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Water Temp Gauge Problem


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#1 Jakemini551

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Posted 15 January 2019 - 09:34 PM

Hello guys I am currently new to this forum I am currently doing a light restoration on a 1993 spi 1275 but I am having a bit of a problem with the water temperature gauge not working I have tested my water temp sensor underneath the inlet manifold whilst it's out of the car with my multimeter and also whilst it's in the car I'm getting all the right readings when the sensor has warmed up its reading a low ohms resistance so I know it's not the sensor but I ain't getting no temperature readings at the gauge iv taken the gauge out and tested it to a known power supply and the gauge goes up to red no problems so I also tested for voltage at the multi plug behind the gauges iv checked the Haynes Manuel for the correct pin for the gauge and I have tested there is continuity from the ecu to the gauge so there is no brake in the cable (also tested the water temp sensor 2 pin plug back to the ecu) but I ain't getting no voltage at all on the multi plug pin 3 behind the gauge black/green cable?

#2 richmondclassicsnorthwales

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Posted 16 January 2019 - 11:53 AM

Firstly, welcome to the forum.

 

I have to say I am not to savvy with the printed circuits on those type of gauges or with SPI and ECU.  My newest Mini I ever had was a Mini Advantage from new back in 1987. The majority were all the old centre 3 clock versions with carburetters.

 

What I have experienced is that the printed circuit can sometimes be troublesome in respect of burning out or not mating correctly with the connector from the main loom. This is something that I can only contribute I am afraid. You have a multi meter which is invaluable and you seem to be finding your way very well. 

 

I am sure someone will have a lot more to add to your question who has a better knowledge of the more modern Mini, meanwhile, welcome to the world of Mini !



#3 genpop

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Posted 16 January 2019 - 12:45 PM

Hi,

what about your fuel gauge? If that is not working too, then it is the voltage stabiliser. You may find more answers if you look in the spi/mpi part of this forum.



#4 Jakemini551

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Posted 16 January 2019 - 10:15 PM

Hello thank you for welcoming me on the the forum yes iv quick handy with a multimeter as I am a electrician by trade so I'm rather good with general electrics I don't have a problem doing electrical work on the car as all its only with the ecu and engine management as you say my first mini was a 90 rover single carb but I seen this one at a good price so I thought why not. But I have check the incoming cable into the multi plug and I'm getting continuity from the ecu pin right the the pin on the multi plug so I don't have no problems in the circuit right up from the ecu pin up the cable and through the multi plug but I ain't getting no voltage at all at the multi plug. Hello genpop yes my friend my fuel gauge works fine that's no problem at all but the water gauge on getting resistance on my water temp sensor and there's water flowing through the inlet manifold as I know these can clog up but I have check it it was blocked but it's not unblocked and rubber pipes inspected only thing I can think that it's not getting anything at the gauge is the actual ecu it's self?

#5 Jakemini551

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Posted 16 January 2019 - 10:15 PM

Hello thank you for welcoming me on the the forum yes iv quick handy with a multimeter as I am a electrician by trade so I'm rather good with general electrics I don't have a problem doing electrical work on the car as all its only with the ecu and engine management as you say my first mini was a 90 rover single carb but I seen this one at a good price so I thought why not. But I have check the incoming cable into the multi plug and I'm getting continuity from the ecu pin right the the pin on the multi plug so I don't have no problems in the circuit right up from the ecu pin up the cable and through the multi plug but I ain't getting no voltage at all at the multi plug. Hello genpop yes my friend my fuel gauge works fine that's no problem at all but the water gauge on getting resistance on my water temp sensor and there's water flowing through the inlet manifold as I know these can clog up but I have check it it was blocked but it's not unblocked and rubber pipes inspected only thing I can think that it's not getting anything at the gauge is the actual ecu it's self?

#6 area51

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Posted 16 January 2019 - 10:18 PM

There can be a problem in the printed circuit board.

Where the copper on the board bends at 90 degrees at the connection point to the clocks to allow a circuit to be completed at the connector, after many years a hair line crack can appear in the copper line. It is difficult to see and is best tested via a meter, 

The hairline crack will not allow a voltage to flow to the gauge.



#7 Jakemini551

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Posted 16 January 2019 - 10:21 PM

Sorry guys my phone is being a nightmare for typing lately haha but yeah basically iv have checked for continuity from the ecu pin right and and through the multi plug for the gauge and I'm getting it even on the out going of the pin so the multi plug is fine but iv have checked my inlet manifold it was blocked but it isn't now and I have also inspected the silicone pipes to check there's no blockages in them and they are fine the only thing I can think it is. Is the ecu itself as I have tested everything and it all seems to be working fine but i just aint getting no voltage from the ecu?

#8 Jakemini551

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Posted 16 January 2019 - 10:23 PM

Thank you area51 I'll try this tomorrow but surely I should be getting something on the pin when the engine has warmed up and running shouldn't I as i ain't getting nothing?

#9 genpop

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Posted 17 January 2019 - 07:16 AM

The ecu is the ground connection, plus is coming from the voltage stabilizer.

You will find a wiring diagramm in the Wekstatthandbuch3 here:https://www.miniscen...nload/download/



#10 Jakemini551

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Posted 17 January 2019 - 01:57 PM

Thank you genpop I have the Haynes Manuel in my garage that's how I found the cable colour and pin for it but I ain't getting no voltage on it at the multi plug

#11 genpop

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Posted 17 January 2019 - 04:27 PM

May you post which haynes wiring diagramm you have? On Spi , the voltage stabilizer gets its current over inlinefuse . The stabilizer is part of the gauges.The stabilizer provides some signal lights with current and fuel and temperature gauge with approximately 10v.This is done by printed or film lines like area51 wrote already.You have to check if there is connection between stabilizer and temperature gauge.Have a look to the manual I already told you.



#12 apcherry

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Posted 17 January 2019 - 11:27 PM

Hi - another noobie here but I've had a similar problem with my recently bought Mini SPI and the temperature gauge apparently not working. It may or may not help because I'm not sure what your electrical tests have prove one way or another. I'll just put forward my experience for consideration - if you think it's not relevant then fine - it's just a suggestion.

 

I had a problem that the temperature gauge didn't seem to be working. The fuel gauge was working fine which after a little reading as genpop indicated ruled out a problem with the voltage stabiliser. With my Mini it had had 12 previous owners and my suspicions are it was used semi-competitively due to a few mods and car club stickers. With my cynical nature I assumed that one of the previous owners had simply removed the thermostat and the engine simply wasn't heating up.

 

Having read around on the subject there seems to be a few variations in recommended thermostats - I decided on a 82deg. thermostat given my use of the car and current conditions and ordered one from Mini Spares. I got round to fitting it on Sunday and when I took the thermostat housing off I was surprised to find that there was one in there - marked as an 88deg. unit. I swapped it anyway for the new one and it's completely different. According to the temperature gauge the engine is getting up to normal operating conditions within a couple of miles - I'm getting more heat out of the heater etc. So for the price of the thermostat and a gasket (less than a fiver) it's made a noticeable difference - for the better.

 

I've just tested the old thermostat I took out in a pan of water warming it up on the stove. Bear in mind it's marked as an 88deg. unit it was fully open just before it got to 50deg and left to cool it was still partially open even at 40 deg. I have no idea how the coolant flow works with the heater and the inlet manifold so I have no clue on how that would affect the temperature sensor. However my suggestion is that for less than a fiver I would say it's worth putting in a new thermostat before you do any more electrical testing just to eliminate that variable from the situation.


Edited by apcherry, 17 January 2019 - 11:27 PM.


#13 andyapanel

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Posted 18 January 2019 - 01:05 PM

I used to have to tap the temp gauge on one mini to encourage it first thing in the morning.



#14 Jakemini551

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Posted 18 January 2019 - 07:30 PM

Thank you apcherry I have been doing some work on the knuckle joints and it did cross my mind about the thermostat so I have ordered one as you say for the sake on £5 I may as well but when I say I tested my sensor I only had the ignition on which the gauge should still be working with it on and I ain't even getting signal voltage up to the multi plug for the dash when iv tested the sensor and heated it up out of the manifold with the ignition on its baffling me and I have tested everything but it all seems to be a full circuit and no shorts :/.




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