ECU water temp sensor - which wire's which?

I picked up a replacement ECU water temp sensor connector (square one on the left as you look into the engine bay), and in the process of getting the old one off, I managed to snap both wires where they are soldered to the pins. This didn't take much effort, so I think that they may have been mostly broken anyway.

My delemna now is, which wire goes to which pin on the new connector?

As you look into the connector, there's a keyway that matches a ridge on the sensor, so that it can only fit on one way. The wires from the harness are coloured black and yellow (with green stripe).

Could anyone let me know, as you look at the inside of the connector, with the keyway at the top, which wire goes to which pin?

Cheers
Pete

 

Don't think it matters, The thermister that is inside is isolated from the case anyway.

As it resistive you can connect it anyway without issue

 

Umm, I think it does matter as per FSM ------>

it shows that the yellow/green wire goes to the sender pin closest to the protuding ridge ... umm- look at the manual diagram to explain that better.

I'm sure I've wired it up both ways in the past and it has worked fine but best to do things by the book.

You'll be better off adding a section (say 3 inches)of twin core 3mm wire so the wires aren't under too much tension as they go into the connector.

PS: Really good to see that I'm not the only obzessive one replacing/cleaning electrical connectors :wacko:. It is astounding how many zeds I see lately that have dirty terminals... I reckon we could set up a side business to the import scene (replacing/cleaning all electrical connectors) to fresh imports.!!!

 

Re: Umm, I think it does matter as per FSM ------>

Thanks, Mark. I was looking at that very same diagram in the Service Manual when I read your reply, and came to the same opinion that the diagram seemed to indicate the shape of the connector and the keyway in relation to the wiring.

Will give it a go. What's the worst that could happen if I get it wrong way around? :wacko:

Cheers
Pete

 

No harm to my knowledge... I have done at least

a dozen of these and tested my own both ways and it seems to work fine either way but there must be a reason why it says that in the manual.

In practice the FSM says the ECU sends a 5 volt signal from pin 28 (yellow/green wire) to the temp sensor and measures the return signal via pin 30 (black wire).

With increasing/descreasing temps, the sensor changes the resistance (not sure which) and the resulting output tells the ECU what temp the engine is running at.

Here's K-Zed's research from his TWD article if anyone's interested (look at bottom of this page)...

 

Just get a multimeter

and test each terminal to the sender body. If they measure open circuit then it doesnt matter which wire goes where.

 

Re: No harm to my knowledge... I have done at least

After deciding I'd go with the yellow/green wire closest to the keyway slot, and add a couple of inches of wire for a bit of extra slack as you suggested, I took special care to ensure that the connections were good.....and managed to wire it up back-to-front! :LOL::LOL::LOL: The old addage "look once, look again, and then check it once more" really is true.

Anyway, seems you're right, Mark, about it working both ways around. Took it for a drive today, and it went fine...temp gauge looked normal....and nothing blew up!
:thumbsup::LOL::LOL:

Cheers
Pete