New EGT Probe not working?

[critta11]

I've bought a egt gauge off ebay for $50 yeh it's cheap but you'd think it would still work to some extent.
Wired it all up and nothing. . .
I've taken out the gauge and tested straight on battery,
Lights work
+ and - on battery, Needle jumpes to max.
With + and - both still connected and blue and white wires connected to probe needle drops back to min (2) but with car going the reading doesn't change. . . Any thoughts?

[the evil twin]

Given that the maximum voltage from the Thermocouple the gauge is looking for is 50 millivolts I would have jumped to full scale as well if you put the battery voltage across the terminals.
You may have fried the gauge but they can be pretty tough and it may have survived.

When you say "it doesn't move with the car running" do you mean sitting there idling after start?
If so that is normal (up to a point)... take it for a drive and see if it moves with a load on the engine.

How is the thermocouple mounted? Did you drill and tap the exhaust for a probe or is it a jubilee clamp type

[the evil twin]

... just reread your post.

You mention blue and white wires.
K type are usually Red and Yellow (Yellow is +ve and Red is -ve)
Are you sure you have the correct thermocouple and are you sure the polarity is correct.
In thermocouples white is usually +ve

[critta11]

From the very basic instructions I got with the gauge it says to wire the red to battery and black to a ground which I did. The probe has a bung that I welded in just under the heat sheild and screws Into that. The probe came with the gauge so I assume it's compatible. Blue and white wires from probe and blue and white wires from the back of the gauge that I assume you join. I had a drive with no change. Could it be a faulty probe?

[critta11]

I didn't put the white and blue wires on the battery I just joined them at the back of the gauge

[the evil twin]

I didn't put the white and blue wires on the battery I just joined them at the back of the gauge

Ahhhh... my bad... I misinterpreted your post.

Thermocouples themselves are pretty tough.
If you have a multimeter disconnect and check the thermocouple lead for a short from blue to vehicle earth and white to vehicle earth (the resistance should be very very high)
Put the multimeter positive lead on white and the neg lead on blue and you should have a low resistance.
If that is the case you could assume that the thermocouple is probably OK

Do you have a brand name, part number or link for the gauge?

[critta11]

Okay I'll try that tomorrow. Here's the link
http://m.ebay.com.au/itm/131074999247?nav=RVI&sbk=1

[AB]

If you work out what the problem is then I would also rewire the power to an ignition wire rather than direct to battery.

Mine is currently wired to battery as well and it does drain the battery a bit.

[Oldmate1]

Hey mate the type k probes that have blue and white cable
Are usually the cheap ones and can only handle up to about
400 deg c. Go to onetemp they make the probes in Australia
And are about $50

[critta11]

I tested the resistance + on white and - on blue and got around 0.40
Not sure what you mean by the first bit

[critta11]

That's after a short drive if that makes any difference

[trekster]

I had similar issues previously, don't solder the thermocouple wires as that can cause issues, if you need to extend the probe wires use proper thermocouple wire, use lug crimps to join the wires. If the wires are the wrong way the gauge won't read, mine didn't read for a little bit then started working, mines about 3" off the turbo.

[the evil twin]

Hey mate the type k probes that have blue and white cable
Are usually the cheap ones and can only handle up to about
400 deg c. Go to onetemp they make the probes in Australia
And are about $50

If they are K type and don't handle past 400 then I agree that they are rubbish and no wonder the colours are dodgy


Okay I'll try that tomorrow. Here's the link
http://m.ebay.com.au/itm/131074999247?nav=RVI&sbk=1

Strewth their Gauge AND Thermocouple are $54 and they say "Beware of cheap imported copies"

I would cut my losses and buy a decent brand but up too you.
You have continuity thru the thermocouple so it isn't open circuit.
The other checks are to make sure neither lead is shorted to earth.
You could try reversing the wires, if they haven't followed the international standards for colours they may have ignored polariy conventions as well
If that checks out then you could try a replacement gauge but you would still have the dodgy thermo

[critta11]

If they are K type and don't handle past 400 then I agree that they are rubbish and no wonder the colours are dodgy



Strewth their Gauge AND Thermocouple are $54 and they say "Beware of cheap imported copies"

I would cut my losses and buy a decent brand but up too you.
You have continuity thru the thermocouple so it isn't open circuit.
The other checks are to make sure neither lead is shorted to earth.
You could try reversing the wires, if they haven't followed the international standards for colours they may have ignored polariy conventions as well
If that checks out then you could try a replacement gauge but you would still have the dodgy thermo

I may just get a new gauge if all else fails, what's a good one to get that's similar looking to that one as I have a saas boost gauge that looks similar.