Temp Sending Unit? (1 Viewer)

[VTCDN]

great info. So... is there an updated part number? Of do i just need a 12volt--> 10Volt stabilizer (ie: radio shack, etc.)?

(yes, i'm having the same issue )

Yes I added the leads to 1362674 , I i think (didn't test voltage , but believe is 5 volt reference) But then again when we say it's 12 Volts , we never say running voltage of 14.5 voltage.

I also run a second set of extra external gauges.


Thanks for the PM reminder .

VT

 

[Spike Strip]

VT, great info! Thanks much ... But one more thing: you say you clipped a couple wires in the internal (fuel gauge) voltage stabilizer...

Can you use this pic to show which ones ?

Or I can post a better, closeup shot.

 

[Spike Strip]

Pic of Fuel Gauge and Voltage Regulator (stabilizer) on right side. Large black cylinder with two wires out the top is a capacitor. Stabilized voltage is fed to the Temperature gauge. If the volt reg is bad, you get the spiky or inaccurate temp readings. What VT has done is essentially cut the old-style mechanical voltage stabilizer out of the circuit and inserted a modern solid-state one.

In lower pic, Red is fuel gauge out to Green, temp gauge regulated voltage pos.
.

 

[VTCDN]

Yes Sir. correct area and wire.
That spot.

That point is the "out " or feed to the Gauges (two units) .
Also the very thin wire on that side that feeds the heated bar .

Now DON'T Destroy the cuts , just in case you need to solder a goof.

VT

 

[VTCDN]

Plus measure the voltage of the stock unit , and the Voltage stabilizer unit can be given power and ground and check for stabilized voltage. Should be 5V , but im going off memory of months ago.

VT

 

[Spike Strip]

OK - ** EDIT after talking to VT **

(as a note: if that screw next to the contacts is turned IN, voltage is increased. If turned OUT, voltage is decreased). FSM says voltage should oscillate between 2 and 7 volts.

Wires to cut ...
.
.
.

 

[Spike Strip]

VT, I think this is the Radio Shack Voltage Regulator you were talking about:

5V stabilized. A lot cheaper than the Volvo one, too.

+5V Fixed-Voltage Regulator 7805 - RadioShack.com

 

[VTCDN]

A-yup that's what I did, My fuel and temp gauge had slightly different (lower by 1/2 needle width) than with the stock setup.

VT

 

[Spike Strip]

Just to add a circuit diagram for the Temp and Fuel Gauge:

 

[BILLBY]

simply nice

great thread ,great response ,should fix up my issue ,maybe next weekend though

 

[Spike Strip]

great thread ,great response ,should fix up my issue ,maybe next weekend though

Post up pix of how you do it and what the gauge reads before and after, if you can.

Good luck.

 

[Spike Strip]

great thread ,great response ,should fix up my issue ,maybe next weekend though

Did you ever try this fix ? Results ?

 

[alaricikyticky]

You are right. I've noticed BOTH go to full and drop back to their respective readings. Scared me a few times.

its not the sender, its the fuel guage actaully, the temp gauge and fuel gauge share the same ground contact which is on the fuel gauge, clean the little points up and it will be fixed, if not get a new fuel guage(about $35) More often then mot the temp and fuel gauge will both act up.........did you notice the fuel guage bounce or peg out at the same time?

 

[gifu]

The fuel and temp gauge run off a strange little voltage regulator built into th gauge. It looks like a tiny little contact and magnetic switch. I think the way it works is it opens and closes quickly, and the 12 volt is dropped to about 6 volt. This little doodad goes bad, and gives full 12 volt to thse two gauges which make them spike. I was able to rewire my fuel and temp using a 6volt transducer (is that the right word) about the size of a piece of gum.

Gauges stopped working, though the voltage is a tiny bit low. I tried 7 volt, and it was too high.

 

[gifu]

Sh** I meant: "gauges stopped spiking".

ie: it fixed the problem.

 

[lifes a beach]

My temp gauge is doing the same thing... more often than not now. My fuel gauge doesn't fluctuate but my battery voltage gauge does. I have had to put in coolant about once a week, but see no leaks. I sometimes hear a "gurgling" sound inside when i start it and hit the gas. I noticed last night my heater doesn't get hot (it did 2 days ago)... possibly air in the line and the heater coil went out?

 

[gregnash]

Gurgling or sound of mice in the dash is normally a sign of air in the system and time to "burp" it. From there if your heat is only luke warm at best after the engine is at full operating temp then your T-stat is likely stuck in the open position or failing.

 

[davew]

This is awesome. My temp guage did this spiking thing for the past two years. It started acting up once on a trip where I actually did come close to overheating, but has continued doing so for the past two years and I had no idea it could be this. I'm just going to get a new guage.

 

[Spike Strip]

Gauge.

It's NLA from Toyota. Used ones may have the same problem. Best to either fix as outlined above, or put in an auxiliary mechanical temp gauge. There's a good thread on that, too, started by JLH911

 

[Spook50]

Pic of Fuel Gauge and Voltage Regulator (stabilizer) on right side. Large black cylinder with two wires out the top is a capacitor. Stabilized voltage is fed to the Temperature gauge. If the volt reg is bad, you get the spiky or inaccurate temp readings. What VT has done is essentially cut the old-style mechanical voltage stabilizer out of the circuit and inserted a modern solid-state one.

In lower pic, Red is fuel gauge out to Green, temp gauge regulated voltage pos.
.

Just did some experimenting with mine trying to find the ideal voltage for these gauges (5V was way too low, 6.3V was closer, but still low) so I can design a more or less bolt-in design for a solid state regulator that I can sell on a small scale to hopefully fund a couple Cruiser projects and some better electronics equipment so I can do more work at home.

Anyhoo, that black cylinder is actually a small inductor. I've seen other small DC inductors that look exactly like that so I hooked it up to a function generator in our lab and hooked up the oscilloscope in parallel and sure enough, it tested out as a 91uH inductor. Here's a similar one without the shrink wrap cover that's rated for 95uH: http://www.digikey.com/product-detail/en/682AE-014=P3/TKS1200-ND/260059

I'm curious what the manufactured spec and tolerance were. That and I wonder why they bothered putting an inductor on a mechanically switching DC regulator when a capacitor would've made a lot more sense in this application to "smooth out" the voltage fluctuations.