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Resistor in temp gage sending wire

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AroostookTR7 Avatar
AroostookTR7 Keith Brown
Washburn, Maine, USA   USA
1980 Triumph TR7 Drophead "Geraldine"
Does anyone know the resistance rating of the in-line resistor associated with the temperature sending wire on a TR seven ?
After replacing the temperature sender and repairing the wire connection, my temp gage is now functional, However in the process I broke the wire off the resistor. Completed the connection anyway to see if it would work. Gage works, but moves only 0 to 25%. Am I correct to assume the resistor is there for span control on the gage?

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TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
Where exactly is this resistor and what does it look like. I have several spare "parts" harnesses and might be able to cut it out for you or at least put a meter on it and get a reading.

AroostookTR7 Avatar
AroostookTR7 Keith Brown
Washburn, Maine, USA   USA
1980 Triumph TR7 Drophead "Geraldine"
The resistor was in-line, about 6" from the sending unit.

On my car, the green wire (and the resistor) was enclosed in a plastic sleeve, that I assumed was intended to be a heat shield to protect the wire. The resistor was poorly installed (soldered), with one connection so loose that I believe it was the cause of the temp gage not functioning.

Will upload a photo of it tonight, when I get home.

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Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, Oregon, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1489449 by AroostookTR7 Does anyone know the resistance rating of the in-line resistor associated with the temperature sending wire on a TR seven ?
After replacing the temperature sender and repairing the wire connection, my temp gage is now functional, However in the process I broke the wire off the resistor. Completed the connection anyway to see if it would work. Gage works, but moves only 0 to 25%. Am I correct to assume the resistor is there for span control on the gage?

Keith:

This sounds suspiciously like a hack intended to get an incorrect replacement sender to read correctly on the gauge. You see some pretty weird stuff perpetrated by previous owners in the name of keeping the car on the road.

I bet you can remove that resistor entirely if you install the correct temperature sender.

All in my humble opinion, of course.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

AroostookTR7 Avatar
AroostookTR7 Keith Brown
Washburn, Maine, USA   USA
1980 Triumph TR7 Drophead "Geraldine"
Vance,
At second look, I think you are on the right track. Definitely looks amateurish.


Attachments:
IMG_1650.JPG    20 KB
IMG_1650.JPG

davmach1 Avatar
davmach1 Dave Leininger
Andover, Minnesota, USA   USA
1980 Triumph TR8 "The 8"
You can determine the resistance by the color coded bands on the resistor. https://www.allaboutcircuits.com/textbook/reference/chpt-2/resistor-color-codes/

AroostookTR7 Avatar
AroostookTR7 Keith Brown
Washburn, Maine, USA   USA
1980 Triumph TR7 Drophead "Geraldine"
Temp gage works without the resistor, reads 1/4 scale warmed up with new sender and 180 deg thermostat

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