tylerwilliams

Hi, my temperature gauge never goes further than slightly past the C, it used too, what could the problem be? and instructions on how to fix it would be greatly appreciated.

wde3477

Eh, offhand I would guess your sending unit is failing.

One test is to pull the wire, and then to ground that wire - the gauge should go full scale one way on open circuit, and then the other way on short circuit to prove the gauge is OK - I forget which goes with which.

Not sure about your vintage, but on mine there were two coolant temperature sensors - one for the gauge and one for the computer. The one for the gauge was up by the thermostat housing and had just one wire. The computer sensor has at least two wires to it, IIRC. Not sure what would happen if you go to grounding the wrong sensor leads.

Don't recall the sensor being too terribly expensive - like $10-$15. And, if you replace, don't worry about the new one reading exactly like the old one used to - these sensors aren't real accurate - could be a letter or so off on the N-O-R-M-A-L span.

If you do find it's your gauge - sometimes reseating the connectors into the flexible circuit sheet behind the instrument panel helps - maybe try banging stoutly on the dash first to see if the gauge position jumps.

dirtcrew51m

Possibly the thermostat is also hanging open and the temp of the motor is cool.

Jayver

The gauge would go to "R", stay for a bit then drop down to just above the "C". I just changed the thermostat and now it goes to just above the "N" and stays there. Hopefully this will better my mileage somewhat.

I suppose I could get a better centered reading if I exercised the gauge connectors to reduce resistance or changed the sending unit.

BTW, where IS the sending unit on a '96 4.9L? It's supposed to be on the passenger side of the block but I can't find it. (I'll attempt a bottom viewing when weather permits.)

dirtcrew51m

try on the water pump or water neck, also the hotter the motor the better the mileage as in 180 or cooler compared to a 195 deg.

benbailey84

mine is doing the same thing, it stays just below the "N" i replaced the unit by the thermostat housing along with the thermostat, i know where the other unit is on the drivers side of the motor behind or maybe beside the distributor.

Jayver

The sensor just below the distributor is the knock sensor. The other sending unit on the driver's side is oil pressure.

Here's sensor location.jpg showing where the coolant temp sender is supposed to be. It's marked C150 but damned if I can see it. Everything is squeezed in together on that side.

I put in a 194 degree unit.

Jayver

The temperature sending unit is on the right side of the engine just above the starter motor. It currently reads 9.4 ohms when engine at operating temp. The specs are 74 ohms cold/9.7 ohms hot. With the needle on gauge showing just at the 'N', either the gauge is out or there is extra resistance in wiring/connectors.