2JZ temp sender for conversion

[Daddio]

Quick question: Finishing off a 2JZ GTE into JZA70 conversion, need to sort the temp gauge. 2JZ sender obviously doesnt work with 1JZ gauge, so it seems I need to fit a 7M/1J sender in the 2J motor... The 7M/1J sender is a larger size than the OEM 2J sender, so...is the only available option to drill and tap the 2J to suit a 7M/1J sender, or is there an after market sender available that will fit in the original 2J spot but give the correct resistance for a 1J dash gauge? (I'd prefer to not have an 'aftermarket' type hardpipe/sender thing spliced in the hose if possible)

[wilbo666]

I'm really quite surprised it doesn't work...!

I've put 2JZGTE and 1JZGTE into identical cars (MZ12) and both the temperature gagues have worked so I beleive the temperature / resistance curves are the same.

If you doubt they are the same you could check it a few ways
1) Put both sensors in a pot of water on the stove and slowly head the water while measureing the resistances with a multimeter
2) Look at the Toyota Service and Repair Manuals (TSRMs) for MA70 and say JZA80 which will have the temperature / resistance curves that you can compare.


Personally if I had to take a guess as to you what your problem is I would suggest that perhaps the sensor ground for the dash is not connected, as a result of the engine swap! Have you tried testing the gauge / wiring etc by shorting the temp sensor plug pin on the engine to ground? (this should read as high high temp on the gauge I beleive)

Cheers
Wilbo

[dumbass]

i will work
u prob left an earth off
go over your diagrams and find the earth

only way it wont work is maybe on the very very late 2js dont have a temp sender
as its all canbus thru ecu

[Daddio]

Thanks for the replies gentlemen...
Having checked the two TSRM's as per Wilbo666 suggestion, it appears the resistance curves are quite similar:
MkIII (7M & 1JZ) Nippondenso 50 degrees 198.5 ohms +/- 33 ohms, 120 degrees 19.6 ohms +/- 2 ohms (the Yazaki sender appears to be identical despite not having values at 50 and 120 degrees)
MkIV (2J 1998) 50 degrees 160-240 ohms, 120 degrees 17-21 ohms

When the temp sender wire is connected, the gauge goes straight to the top of the scale (with engine stone cold). Given the gauge earths through the sender, and everything else on the dash/gauges is working fine this suggests that perhaps the sender is dodgy or I have cocked up somewhere with my splice between the JZA70 dash loom and the Aristo/2JZ engine harness.

Its my first go at a Toyota engine swap harness, so no doubt lots to learn

[dumbass]

Send me your harnesses and I'll fix your problem hehehe

[Daddio]

Send me your harnesses and I'll fix your problem hehehe

lol...thanks for the offer, but I'm keen to learn (or just stupidly stubborn!)

[midnight_purple_GA70]

ive dont this in a 1jz into an ma70 and it worked... but think we had to either give power or ground to a wire behind the dash...

[wilbo666]

I stand by my first comment of it being a wirng issue .

The gauge shooting straight to the top indicates a short to ground.

You'll want to check the JZA70 to JZS147 wiring as you have said

Not sure if you've seen my wiki which details the JZS147 side... the JZS147 dash temp sensor comes out on pin F9
http://wilbo666.pbworks.com/w/page/3...BodyLoomPinout

Cheers
Wilbo

[Daddio]

Thanks Wilbo, yes have been using both your write up and the one from SupraNL as guides (Your efforts to document are very much appreciated!)

As you say, I've probably made an error in the wiring side...(I have been doing it very slowly, one wire at a time for the dash stuff, and testing each item before solder/shrink tubing it...tedious, but the only way us beginners can learn! Oh, doesn't help being color blind either!)...I'll go back and check again (still easy as every wire on the A70 harness plugs and every wire on the ECU plug still have my labels on )

[dumbass]

Check the earth from temp gauge to the block
Toyota fkt up when they designed this
Earth for temp gauge is on block not behind dash
I guess they did this incase umhave be engine earth it doesn't make gauge read funny
Just a head fk to diagnose if u haven't done it before
I've fixed this issue bout 20 times for inexperienced mechanics

[Daddio]

Check the earth from temp gauge to the block
Toyota fkt up when they designed this
Earth for temp gauge is on block not behind dash
I guess they did this incase umhave be engine earth it doesn't make gauge read funny
Just a head fk to diagnose if u haven't done it before
I've fixed this issue bout 20 times for inexperienced mechanics

Thanks, all info is good info..Are you suggesting the earth from engine block to chassis/loom? The temp sender is a single wire sender, thus earths through the block (unlike the ECU sender which has two wires)

[dumbass]

Temp sender has one wire
But the gauge has three wires


Ign
Ground
Signal

The ground does not connect to ground for the other gauges
It goes thru body loom into engine loom then earths on block

[Daddio]

Temp sender has one wire
But the gauge has three wires


Ign
Ground
Signal

The ground does not connect to ground for the other gauges
It goes thru body loom into engine loom then earths on block

Aha! Thanks for the explanation! Its highly possible I haven't connected that earth yet...I will check it out

[Daddio]

Just to confirm, the issue was the extra earth for the gauge...wired in and we now have a working gauge
Many thanks to both Wilbo and Dumbass for the pointers

Can now move on to the hydraulic fan controller and PPS stuff...