TheSamba.com :: View topic - ISO WEST wiring diagram for oil temp. gauge.

Sat Jul 19, 2025 3:04 am

Sorry to bother. I had it all working until I dressed up the harness and now I don’t know what wires went where.
1-bundle
2-white wires
1-black wire

On the other bundle.
1-yellow 1- blue
1-red
1-black

TIA.

Sat Jul 19, 2025 7:52 am

I dont know, but...

Assuming the gage is lighted, one wire is positive 12 volts, and another is likely ground. The last wire is then likley the signal wire from the sender. An ohm meter can be used to detect the ground and signal, and turning on the headlamps and or ignition should finf the 12 volt positive.

On the gage, if that is the second bundle listed, I assume black is ground, red is positive 12 for the light , and the yellow/ blue wire is the sender wire

note id not try putting 12 volt nor an ohm meter on the gage as if you do that to the signal wire, it may ruin the gage

So the safe thing to do is to warm up the sender, either by running the engine or heating the sender with a heat gun or such. the sender must however be grounded (attached to the engine) for this test to work
once warmed up. and assuring that the wire you select is not 12 volt, you may touch it to the gage wires to see if you get meter movement. You will need the gage ground, so for test Id ground the gage black wire to body and then breifly, quickly touch the sender wire to the blue/yellow wire while watching the gage. make thks a very rapidly, brief touch, just in case you got it wrong. watch the gage when doing this, if gage pegs either way, you know it is wrong, and if a brief touch of the wire you probably wont harm the gage if it was brief.

Now some gages do require positive 12 supplied to read, so in that case you will need to connect that, but again do a very rapid brief, touch of the wires as you watch so as to not peg the needle. there is some risk here, but short kf a wire diagram, you are stuff.
I did not see iso west gages on an interweb search, maybe you can search more?

this technique of a breif touch of wires is called flashing the meter, a technique once common when using a volt meter, back in the old analog meter days, it saved many a meter from destruction when the polarity of the test circuit was not known. I am old and learnt it that way, that is how I roll. this is not needed to do with modern digital volt meters, as they dont care about the polarity

Sat Jul 19, 2025 9:52 am

Thank you.

Sat Jul 19, 2025 3:13 pm

Are there any letters or numbers on the gage itself ? S usually means that is the terminal to the Sender for instance.

I think I misunderstood, you have four wires not three correct?

If so you likely have a 12 volt positive that is on with the ignition, in addition to the 12 volt positive for the lighting. then you have a sensor wire and a ground., thus four wires.

you have one bundle,of three wires and another of four?

Which bundle is from the gage? What wires gone from the gage? again is there any numbers, or even symbols or letters on the gage at the terminations?

Perhaps you can provide a photo of the rear of the gage?

Is there any other wording on the gage? I still cannot find "Iso-West" as a gage maker