Triumph Repair: Temp guage sending unit, gauge needle, temp gauge

Question
QUESTION: hey Howard,
Just a follow up to my question below.
So i bought a new temperature sending unit from NAPA, part #TS6056
I installed it and my temperature gauge goes to full hot but when i check it
with a light meter, i get no pulsing light.

When i plug my old one in, i get pulse on the light meter but i get no
movement on the temp gauge on dash...

what gives?


Hi Aron,
The preliminary tests for the temp gauge is to turn on the key and remove the
wire off of the sending unit and watch the gauge. The needle should go full
deflection. Then ground the wire just for a second or two and the needle
should go all the way in the opposite direction. Then if that don't work, check
the voltage at the power side of the gauge. It should be 10 volts.

However if you see a pulsing signal at the sending unit with it connected, it
sounds like you have a bad sending unit.

Howard

ANSWER: Aron, you need to run the tests I told you to run and check the voltage supply like I told you (10 volts) Stop buying parts until you run the tests.
Howard

---------- FOLLOW-UP ----------

QUESTION: Hey Howard,
Thank you for being patient and I have some answers for you.

When the temperature sending unit (TSU) is disconnected, the gauge reads 0 (zero). When the TSU is  connected the gauge reads Max Temp.

Now for voltage test results:
First off, the voltage jumps around a lot, is that normal?

Volts on gauge unit when NOT connected jumps around from 4 v to 11.30v

Volts on gauge, when TSU is connected reads from .07 to .35v

What does this tell you, if anything?

thanks
aron


Answer
Aron, your test of disconnecting the gauge is not the test I told you to do. I said to disconnect the wire and the gauge needle should go full deflection and ground the wire and the gauge should go full deflection in the opposite direction. The fact that you connected it to the sending unit (instead of grounding it) and it went full deflection clearly indicates the sending unit is probably bad or the wrong unit.

My mistake on your voltage readings as I should have warned you to use a analog meter unless your digital meter has an option to give average readings or smooth out fluctuating readings. The voltage stabilizer that powers the gauge vibrates to drop the 12v power to 10v so a digital tries to look at all of the changing voltages. Thus you can't read it.

Tell me again what kind of car this is so I can look to see if I can come up with a ohms reading of the sending unit at different temps.
That way you can evaluate that NAPA sending unit. (and the old one)

Howard