Looking for dummies guide for temperature guage wiring

Gotta love that wiring . . .
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Spiderinmlnj

Looking for dummies guide for temperature guage wiring

Post by Spiderinmlnj »

Help

Just acquired an 82 spider and starting to run down it various quirks.

Issue that i'm currently working on is non functioning temperature guage.
Wire from senders on block are tied together under hood and go nowhere, so clearly this is part of the problem :-)
It appears that the guage moves on less resistance and not more resistance as indicated in the manual and in a couple of threads on this board. If i ground out the green wire post on guage needle moves hard right.

Now my key questions are:
1) where under the hood should the green/white wire become visible and split off to the two senders?
2) where does the resistor that forms part of this circuit live?
3) what are the specs for resistor mentioned above?
4) is there any easy way to tell the temperature sender from the kill sender? It seems that there poision on the engine may not always be same (or they may be swapped)
5) does anyone have a list of resistance of sender at different temps?


Thanks for helping a new owner

Geoff C



Appears that
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azruss
Posts: 3659
Joined: Sun May 30, 2010 12:24 pm
Your car is a: 80 Fiat 2000 FI

Re: Looking for dummies guide for temperature guage wiring

Post by azruss »

Here is a pic of my 80FI. you can see the 2 temp gage sensors with wiring. Sorry i dont have anything better. didnt know there was a resistor in the circuit. definitely not under the hood.

Image
Spiderinmlnj

Re: Looking for dummies guide for temperature guage wiring

Post by Spiderinmlnj »

Well this is what I think I have learned so far:

Resistor between cut off and sender lives in blue holder (similar to a fuse holder) above gas pedal.
This resistor appears to measure out at 320 ohms.

The guage reads higher as resistance is lowered:
120 degrees (on guage) is about 790 ohms
155 degrees (on guage) is about 385
190 degrees (on guage) is about 120
225 degrees (on guage) is about 108
red on guage is about 70

Don't check resistance of sender when ignition is off and wires attached as something else gets closed in circuit giving a value that does not help.

And now time to replace the sender and see if all my theory works well in practive :-)
rrrrob
Posts: 48
Joined: Tue Jul 12, 2011 5:21 pm
Your car is a: 1975 124 Sport Spider
Location: SE WI

Re: Looking for dummies guide for temperature guage wiring

Post by rrrrob »

Geoff,
Would it be possible to post a picture of this resistor? I haven't been able to identify it.
Thanks
Rob
1975 124 Sport Spider<br/>
1979 MGB<br/>
1981 Mazda RX-7<br/>
2002 Chevy Blazer<br/>
2003 Mazda 6
Spiderinmlnj

Re: Looking for dummies guide for temperature guage wiring

Post by Spiderinmlnj »

Hope these help The first one shows where it hides - over the black box above accelerator
In the second the tube on the right hand side is the resistor holder

http://www.flickr.com/photos/65941128@N06/6003653488/

http://www.flickr.com/photos/65941128@N06/6003653452/

To tired to figure out why not displaying in post :-)
rrrrob
Posts: 48
Joined: Tue Jul 12, 2011 5:21 pm
Your car is a: 1975 124 Sport Spider
Location: SE WI

Re: Looking for dummies guide for temperature guage wiring

Post by rrrrob »

Thank you
1975 124 Sport Spider<br/>
1979 MGB<br/>
1981 Mazda RX-7<br/>
2002 Chevy Blazer<br/>
2003 Mazda 6
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