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Water Temp Sender Gauge


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#1 Tinman

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Posted 15 February 2017 - 10:22 AM

Morning All,

 

It's a massive amount of time since I've posted on the forum.

 

Just got my ST185 (wide-body) back from a complete engine loom rewire and microtech LT10C install.

 

Problem is that the Water temp sender gauge now only reads low (0) when the single wire temp sender is disconnected and High (low resistance) when the sender is connected.

 

Inspect%20Sender%20Gauge_zps5ktraeyy.jpg

 

The Temp sender resistance is correct 226ish ohms at 50degC and about 140 ohms at 85 - 90 deg C. (I'm not going to let it get to 115deg C to check the 26ohms.

 

Measure%20Gauge%20Resistance_zpss0am60cf

 

I haven't pulled apart the dash yet to check the resistance of the gauge.

 

However, has anyone had experience with what could be causing the IGN ON = HIGH reading on the gauge?

I am wondering if there is something simple like "an earth wire not connected to point "A or B or C" (as I assume the gauge is just a variable resistor type reference gauge).

Thanks all for your help.

There should be more photos on my build thread in the next few weeks.


Edited by Tinman, 15 February 2017 - 10:23 AM.


#2 Tinman

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Posted 16 February 2017 - 02:34 PM

Mmmmm ... factory boost gauge in dash is not working either. Wondering if it is related. 



#3 TD.

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Posted 16 February 2017 - 04:44 PM

What is the common link between the two gauges ?

sharing a wiring connector ?

using the same control module ?



Also, thanks heaps for all the replies. I'm fast learning that this may be the friendliest forum on the internet.

 
/ragequit_life

#4 Tinman

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Posted 16 February 2017 - 06:26 PM

not sure yet .... though i'd ask before wasting time pulling the instrument cluster apart.
 

The toyota ECU is no longer fitted.  So the auto elec may have wired them straight to the gauges.



#5 hemimark

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Posted 19 February 2017 - 02:16 PM

There is a brown wire in plug IJ2 pin 14 that is an earth for the temp gauge if it's not connected the gauge will go to hot as soon as the key is on. IJ2 is down near the ecu so you won't have to pull the dash apart just connect it to a good earth point.



#6 Tinman

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Posted 19 February 2017 - 07:36 PM

There is a brown wire in plug IJ2 pin 14 that is an earth for the temp gauge if it's not connected the gauge will go to hot as soon as the key is on. IJ2 is down near the ecu so you won't have to pull the dash apart just connect it to a good earth point.

 

You were spot on.  BR wire to Terminal 14 of IG2 ... but no earth wire on other side of the connector (brown wire from T14 of IG2 to back of intake manifold).

 

Water%20Temp%20Guage%20Circuit_zpskfvdte

I simply snipped the wire at IG2, extended it with solder/heat shrink/ring terminal, then riveted it to a good earth point in the car body.

 

Gauge is Working now.

Thanks hemimark :)

 



#7 TD.

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Posted 20 February 2017 - 04:49 PM

 

 then riveted it to a good earth point in the car body.

  :)

 

I died a little inside when i was reading that :(



Also, thanks heaps for all the replies. I'm fast learning that this may be the friendliest forum on the internet.

 
/ragequit_life

#8 Tinman

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Posted 20 February 2017 - 05:14 PM

 

I died a little inside when i was reading that :(

 

lol ... attached via screw



#9 TRD-021

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Posted 24 February 2017 - 11:13 AM

The boost gauge is normally connected via the map sensors, I'm guessing your using a different loom so you need to tap into the new map sensor wire, i think it's a red wire. I think it you can find it on the big white plug terminal.
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#10 Tinman

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Posted 24 February 2017 - 08:17 PM

still using the turbo pressure sensor as MAP for the Microtech.

 

turbo pressure sensor wires are

 

P-L (ECU in this case Microtech)

R-W (This should be going through to IG1 connector.

BR (earth)

 

IG1 connector as below

 

Boost%20Gauge%20Connector_zpsikhkzq9g.jp

 

I believe that my wiring is the wrong way around.  I have a P-L (Pink-Blue wire going to IG1) when it should be R-W.  L-R is going from IG1 to gauge correctly.

The R-W may be going to the microtech, I'll check it out tomorrow.

Over and out :)






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