Bleh... Well, you'll have to do some experimenting then. Are you sure there is a good connection all the way from the sendor connector to the back of the gauge (no opens or shorts)? My brand new harnesses from AAW had two issues that needed to be fixed (not temp gauge related)...

The higher the temp., the lower the resistance from the sendor. With another person, you could short the sendor lead to ground to see if it will peg the gauge needle. Though, putting some resistor in there would keep things a little more on the tame side. Say...100 ohms.

Here is something I saved from another thread. It has all the values of resistance at various temps for three different brands of sendors. Your could also heat yours up in some water on the stove and see if the resistance is close to the listings...

quote: Gauge normally reads 1 tick above 1/4 scale with the engine operating around 180 degrees, thats just how the originals work.

Heres some resistance values for three senders 6 dollar TU5 Wells sender from Autozone, 25 dollar "correctly calibrated" Lectric Limited model 01513321, and an original GM 1513321 sender (for a Pontiac Firebird - one with the slide on connector- Camaros use a 1513462 with a screw on lug).

80 degrees: Wells at 650 ohms, LL at 573 ohms, GM at 549

90 degrees: Wells at 526 ohms, LL at 445 ohms, GM at 524

100 degrees: Wells at 429 ohms, LL at 365 ohms, GM at 409

110 degrees: Wells at 328 ohms, LL at 266 ohms, GM at 365

120 degrees: Wells at 283 ohms, LL at 227 ohms, GM at 323

130 degrees: Wells at 250 ohms, LL at 200 ohms, GM at 272

140 degrees: Wells at 216 ohms, LL at 170 ohms, GM at 227

150 degrees: Wells at 198 ohms, LL at 155 ohms, GM at 195

160 degrees: Wells at 173 ohms, LL at 133 ohms, GM at 175

170 degrees: Wells at 157 ohms, LL at 119 ohms, GM at 157

180 degrees: Wells at 135 ohms, LL at 101 ohms, GM at 140

190 degrees: Wells at 120 ohms, LL at 89 ohms, GM at 125

200 degrees: Wells at 109 ohms, LL at 79 ohms, GM at 109

212 degrees: Wells at 104 ohms, LL at 75 ohms, GM at 102

If you have a gauge with an external resistor you can change it from the stock 86 ihm resistor to a 91 ohm resistor and that will move the gauge up to 1 tick below half, at 180 degrees. I've done that, I use a potentiometer with two short leads on it, I adjust it to what i want the gauge to read and then lock it down in a ball of electrical tape so it can't change. If your gauge has the resistor built into it, then you have to live with it reading low, or get a sender that has a lower resistance at each of the temps above. As you can see the LL sender had a lower resistance throughout the range of the instrument for any given temperature so the needle would be higher on the gauge for the same temperature. :unquote