I've been trying to get the gauge working and have had no luck. I have changed the sender in the head and checked the OHM vs ground on it, it was ok. I reran the dark green wire from the gauge cluster to the sender and still get no reading. When starting the car the needle moves all the way up and back down to nothing. The wire from the dash give me +12 volts and when grounded its reads full hot. The sender in the head measures .270 or so ohms read on the 2k ohm setting. The ohm reading from the dash wire is -.308ohm could this be the problem?

 

do you have the correct sensor in the head? parts stores are notorious for giving you the wrong one

 

At what temperature does the sensor measure " .270 or so ohms read on the 2k ohm setting."?

.270 ohms on a 2K ohm scale would appear to be 270 ohms, and that corresponds to 190*F. Use Shoebox's chart of ohms vs. temperature:

http://shbox.com/1/4th_gen_tech2.html#ect

Measuring the resistance across the wire (without being connected to the sensor) would be sort of meaningless, since you are including the resistance of the gauge.

 

The .270 is right around 185-190 based on datamaster and the PCM reading. I was not measuring the lose wire, it was connected to the sender, as was the other end connected to the dash where I found +12v and -.308ohm.

 

You were measuring the resistance of the complete circuit, which is still sort of meaning less. If you have 12V on the wire when its not connected, and the sensor reads the correct resistance vs temp, the gauge may be fubar.

 

You cant measure resistance on a wire that has voltage on it. Not real clear that is what you did or not.

 

Maybe this is a bit more clear

Temp Sender in head>-------------<wire open, measures no voltage and .270ohm at temp

Dash Gauge>------------<wire open, measures +12volts when car is 'on', show -.308ohms, did not measure with no voltage also will peg gauge hot when grounded

Temp Sender>---------<Dash Gauge, still has +12volts and reads -.308ohm the wire from the sender is connected to the dash in this reading.

 

Hopefully is measures 270 ohms, and not .270.

The last two descriptions simply confirm you were doing exactly what Shoebox said wouldn't work - measuring the resistance of circuit that has voltage on it.

Have you verified the continuity of the wire between the gauge and the sensor - i.e. next to 0 ohms when measured from one end to the other, with nothing attached to the wire?