Hi all,
I've done my research but was not able to find this specific info:

- Engine - V6
- Temp gauge fix DONE.
- Problem - No response from temp gauge
- Before installing a new temp sender I would like to "Zero" the needle.

I'm following this procedure:

quote From http://fierosails.com/tempgage.html ZEROING THE GAUGE If your temperature gauge is pointing in some odd direction or seems erratic, you can test it easily if you have the appropriate resistors. Resistors come in standard values and are not available at the specified gauge limits of 55 Ohms and 1365 Ohms. Buy resistors of 47 Ohms and 1400 Ohms to get you in the general vicinity the gauge limits. The position of the needle on the temperature gauge shows the resistance of the element in the temperature sensor. In other words, the gauge is an Ohmmeter. The gauge is supposed to read 100 degrees F when the sensor resistance is 1365 Ohms and 260 degrees F when the sensor resistance is 55 Ohms. To test the gauge for accuracy, pull the plug at the sensor, stick one end of a resistor in the plug and ground the other end of the resistor to the car. Turn the ignition to "On". If you don't get any readings, try the other location on the connector. Assuming the test resistor is near one of the values mentioned above, your gauge should be in the general vicinity of either 100 or 260 degrees F. If not, the needle has probably shifted. Test with both resistors to determine the gauge reads about right at both ends of the scale. To zero the needle on my gauge I simply flicked it with a finger until it was accurate. But if the gauge wiring has not been modified it will continue to "peg" on start and will quickly become inaccurate again. If zeroing the needle will not result in accurate readings with good test resistors then it's probably time to replace the gauge.

- Tested the gauge with resistors - getting good response but how do I actually reset / adjust the needle???
- Does the needle lift from the gauge to readjust?
- When I "flick" it to adjust it basically changes it's position mechanically and now the OFF position is wrong (40*C=100*F)
- Will it stay corrected or readjust itself wrong again?
- Is the gauge itself defective.

Thanks.

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T-Top ~HUD~LEDs ~Red Fieros~Carputer~Montreal Club

You can gently pull the needle off then push back on in the correct location. As long as its not pegging anymore it should remain accurate from now on.

With the key "On" and the engine cold I would just pull the needle off and re-install it pointing at 100. If the gauge reacted properly to the tests sounds like your temp sender is bad.

[This message has been edited by Xanth (edited 04-05-2008).]

quote Originally posted by Xanth: You can gently pull the needle off then push back on in the correct location. As long as its not pegging anymore it should remain accurate from now on. With the key "On" and the engine cold I would just pull the needle off and re-install it pointing at 100. If the gauge reacted properly to the tests sounds like your temp sender is bad.

Thanks Xanth. (+4U)

So the needle does come off ? tried lifting it with no successes so far.
What's a proper Zero for the gauge? 100*F ? even if air temp is below that?
I will get the sender replaced ASAP. is a good used one O.K? or do I have to get it new?

The whole needle base should be able to lift off, mine weren't glued just pressed on to the shaft. Helps if you have fingernails, or find someone who does. Have to be careful not to snap the needle off the base. I'm surprised someone was able to adjust their needle just by flicking it, it should be tight enough on the shaft that wouldn't really work.

The Zero with key On should be at 100, the needle will sit there with the engine cold. I don't think the sender is expensive, but if you have a good used one that would be good to confirm that your old sender was actually bad.

[This message has been edited by Xanth (edited 04-05-2008).]

quote Originally posted by Xanth: The whole needle base should be able to lift off, mine weren't glued just pressed on to the shaft. The Zero should be at 100, the needle will sit there with the engine cold. I don't think the sender is expensive, but if you have a good used one that would be good to confirm that your old sender was actually bad.

Thanks again, I was able to remove it (after you told me it does come off) and consider actually putting a drop of glue so it doesn't "readjust" so easily. After reinstalling - I recycle the switch and if gets out of zero.

NOTE: Good to have at least one Fiero expert on shift LOL. We should have a schedule when there is always one online for "emergencies"

quote Originally posted by Xanth: Helps if you have fingernails, or find someone who does.

I can just imagine coming up to a woman asking for help with her fingernails LMAO

[This message has been edited by Mister (edited 04-05-2008).]

Drop of glue probably will help, trick to get it on the needle but not all over the gauge. Frustrating cleaning glue off the gauge

Once you get the needle to sit at 100 with the key on engine cold, the rest of the range should be about as accurate as the factory gauge can get.

Is your temp sensor hooked up when you adjusted the gauge? Possible the sender is reading bad making it impossible to keep zero. I believe if you unplug the connector on the engine with they key on the gauge will sit at 100 as well. You can re-test it to make sure.

I spend a lot of time on here, even at work I check in regularly from my cell

[This message has been edited by Xanth (edited 04-05-2008).]

Cool!

I understand a new sender would have some type of thread sealer that will conduct the ground (-) from the block to the sender.
If I'm replacing with a used one, will it still seal or do I need to figure it out with a specific sealer?

Just went out and checked on my Formula, with the temp sender unplugged the gauge will point at 100 with the key on. I would try and adjust the needle with the sender unplugged.

quote Originally posted by Xanth: Just went out and checked on my Formula, with the temp sender unplugged the gauge will point at 100 with the key on. I would try and adjust the needle with the sender unplugged.

DONE! WILCO.

I did the same procedure last year on mine
Except it was for the speedo needle .
Hi Mister

Well, just f*^%$*$k lovely...Grrrrr
After zeroing it yesterday, today when I started up the Fiero it's back in it's old place top left... ???
Guess I have to replace the sender and try again, maybe the sender is giving it some extreme low reading. (?)
Doesn't make sense.

~~

quote Originally posted by Robert 2:Hi Mister

Hey Robert

Where does it sit when you unplug the sender? Does it go back to zero or stay way off to the left?

And you've confirmed that your pegging needle repair worked?

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www.FieroDomain.com
"If any car is both the parade and the rain, it is the Fiero"
Live Help!

[This message has been edited by Xanth (edited 04-06-2008).]

quote Originally posted by Xanth: Where does it sit when you unplug the sender? Does it go back to zero or stay way off to the left? And you've confirmed that your pegging needle repair worked?

- when unplugged it stays top left
- Pegging fix done and working.

Had a quick chat with Xanth on his "Live Help" we concluded to re-install (ground problem) the sender and retest it.
Many thanks for the support

...To be continued...

When you plug the gauge back in you load the the wire at the sender with 47 Ohms worth of resistors to ground. Then put the needle on pointing to 260ºF

quote Originally posted by DIY_Stu: When you plug the gauge back in you load the the wire at the sender with 47 Ohms worth of resistors to ground. Then put the needle on pointing to 260ºF

If you're talking about the zeroing procedure, I've done it as described above on http://fierosails.com/tempgage.html
Thanks.

Any updates?

LOL... Nothing yet, I don't have the proper deep socket here. I'll get back to it tomorrow.

quote Originally posted by Mister: If you're talking about the zeroing procedure, I've done it as described above on http://fierosails.com/tempgage.html Thanks.

I was gonna say this , but since you've done it i'll stand still .

I'm really sorry to "hijak" your thread, but I have a similar problem. I tried starting my own thread and replied in several other temp. gauge threads but I've yet to get a reply.

If I plug my sending unit in, the gauge will steadily climb until it pegs and gets stuck, even with the engine off. I've replaced the unit twice, I've had the cluster completely apart and cleaned all contact points on the printed circuit and all the connectors. I've added a new 6 gauge ground cable from the engine block to the body, and from the body to the battery. Doesn't change a thing.
I've removed the sending unit and held it in my hand, run a wire from the body of the unit to the battery ground, and it sits just fine at 100 degrees. But as soon as you screw it into the head and plug it in, the gauge needle starts climbing.

I'm seriously stumped and have been driving around for about a month with it unplugged.


Please somebody, HELP!!!!!!

Oh, the problem is in my 87 GT.

Thanks in advance!

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1984 Sport Coupe Auto.
1985 Sport Coupe 5 Speed
1987 GT Auto.
2006 Jeep Wrangler Rubicon, 5" lift, 35" tires
1975 Cadillac Coupe DeVille, 25,000 original miles
1963 Buick Electra 225
1936 Dodge Two-door Touring Sedan

Are you using thread sealer on the sending unit?

quote Originally posted by 85pontiac:Please somebody, HELP!!!!!!

No Hijacking, it's perfectly relevant. I hope an expert will chime in.

quote Originally posted by Hudini: Are you using thread sealer on the sending unit?

In my case I removed the sender today and found just one loop of sealing tape at the top of the thread, I removed it and reinstalled.
No change - still no response. I'll get a new sender on Sat.

One way to verify continuity is to disconnect the sender, then with the key in RUN, touch one side of the sender's connector to ground. You'll need a paper clip or something stuck into the connector. Either the overheat light will come on or the gauge will peg. Then do the same thing to the other side of the connector. If nothing else it will verify continuity and that the overheat light works. If those check good then time for a new sensor.

I used Rodney Dickman's gauge tester leads and verified I had a bad gauge. After replacement with a Fiero Factory used one, I used Rodney's leads to set the gauge needle to the exact settings.

Thanks. Gauge tested O.K.
I'll update after the new sender.

Any ideas for 85pontiac and the climbing gauge needle ?

the climbing needle sounds like thread tape is being used.

Nope, no thread sealer. I've been driving around with it unplugged, and when you turn the key on, the gauge needle jumps around, "bulb test mix-up", then settles down to just a hair below 100. And I've hooked up various values of resistors to the wire itself, back at the sender, and the gauge reads right around where it should. So I'm not really thinking the gauge itself is bad. And I'm on my second new sending unit, thinking that the first was just bad, but no dice.

Well I hope I didn't kill this thread too.

Someone have any advice?

Fraid I cannot figure out why your needle would do that

I don't know. I think I'm gonna try running a new wire directly from the sending unit, to the back of the cluter (on the correct pin of course) and see what that does. If it works, I'll just route the wire with all the others and make my own fix.

It shouldn't have to run through the ignition switch, like is shown in the FSM wiring diagram, right?

Good news on my front

The sender I've got today


Installed, all nice and shiny


I'm getting what seems to be positive response from the gauge. Did the "zeroing" again (I'm getting faster disassembling the gauges cluster)
And the night test drive was O.K.
We'll have to wait and see if it stays in the right range in a few days.

Thanks for all your help people.

Seems the temp gauge is a "HOT" topic recently (about 5 threads with different problems)

After only 3 days, the needle went back to it's old LOW position. Grrrrrrrr
I'll have to reopen the gauges cluster and glue the damn thing better.

Interesting "fix"....


I have noted that the function of my temp gage appears to be somewhat related to the alternator...believe it or don't....

Until I converted my 87 GT over to a CS alternator this past week, I noted that the temp gage always read higher than normal when the volts were high, (15v), on the volts gage. (I think the regulator in my old SI alt was shot).
Not quite sure what would cause it, but once the volts dropped down to a steady 13v or so, the gage would read read somewhat more accurately. Well, as accurate as Fiero gages read...
I know I'm not imagining this, it's just something I observed. Maybe one of our resident "electronical experts" can try to explain?

[This message has been edited by randye (edited 04-16-2008).]

At this time I would believe ANYTHING about these gauges LOL
It seems every other Fiero has some ghost in them

Not sure what's going on now, but the temp gauge works fine (?) in the first few minutes, them after the engine gets to higher temps the needle DROPS to extreme LOW ??? and stays there until I'll shut it off.

Any ideas?

quote Originally posted by Mister: Not sure what's going on now, but the temp gauge works fine (?) in the first few minutes, them after the engine gets to higher temps the needle DROPS to extreme LOW ??? and stays there until I'll shut it off. Any ideas?

Have you tested the sending unit with the engine hot to see what values you are getting out if it?

quote Originally posted by Xanth: Have you tested the sending unit with the engine hot to see what values you are getting out if it?

Good call Xanth, I'll do that tonight after driving.
I just tested it now, outside temp is 18*C / 64*F and the engine was shutoff 3 hours ago.
It reads 1280 Ohm which is the Ohm level for approximately 40*C / 104*F