Making a MKIII water temp gauge work with MKIV temp sender

[Turbo Skegget]

I have a little wiring problem. I have the MKIV water temp sender on the engine and I have the MKIII water temp gauge in the combination meter. After some calculations which have been proven wrong I soldered in a 27 ohm resistance to get a working gauge. Can somebody help me with this?

 

[dirosa]

what problem are you having with your gauge? it should work fine with the stock 2jz 1-wire sending unit with the yellow-green wire. if you are experiencing your needle peg the HOT area right away, check your dash ground, as without it, this will happen.

 

[Turbo Skegget]

Thx Dirosa, will check that.

 

[Flateric]

Ummm, I don't believe it does actually.....

I ended up using the MKIV temp sensor signal for the ECU. And one of my old MKIII 7M sensors seperately to the guage cluster.

Each has it's own temp sensor that was native to the ecu and the cluster.

I found this the most direct simple solution. I couldn't get my guage to twitch with the MKIV single wire temp sensor. And of course the 2 wire sensor is the one that goes only to the ecu.

I tapped new threads and enlarged the hole where the original mkiv single wire unit originally was.

 

[dirosa]

^ i've wired up 5 different 2j engines, each one with the stock 2j temperature sending unit (1-wire/yellow-green) with no issues whatsoever. maybe your original 2j sending unit was bad?

 

[Flateric]

I'm thinking u gotta be right.

 

[Turbo Skegget]

Dirosa: Do you think I should remove the 27 ohm resistance that I soldered in on the yellow/green wire. When I double checked the TSRM:s they show a 26-27 ohm differense at 90 degrees but almost the same ohm number when 120 degrees.

 

[dirosa]

why did you put in a 27ohm resistor? the temp sensor is a variable resistor that changes depending on temperature, that is how the gauge works, it reads the different resistances of the sensor. take out your resistor, i think 27ohms is too much, should be in the kilo-ohms IIRC.

 

[hvyman]

Ground the brown wire on the m1 connector. Or buy some better gauges and use the sensor supplied with it.

 

[dirosa]

nah, if the brown (dash grnd) wire isn't grounded, the gauge pegs hot. i know because my buddy did the exact same thing with the same symptoms. if his gauge isn't moving, i'm going to suspect a bad gauge, or a fault in the wiring.

 

[Turbo Skegget]

I put in a 27 ohm resistance because the MKIII and MKIV get the same value at 90 degrees then, but after more searching I found out that they have almost the same value at 120 degrees stock so I am removing the resistance.

One more question: I have a late MKIII with the "low oil level warning" and I cant get it to work with the 2JZ-GTE "low oil level warning sensor" any ideas. The TSRMs on the internet never metions how it works on the MKIII.

 

[dirosa]

i'd probably take a look at the two wiring diagrams for both cars. but i thought someone mentioned to me it went through a computer or some controller? maybe look towards that.