If you changed the temp gauge sending unit, come in!
 

1985 4runner 22re SR5

Temp gauge doesn't work properly. Goes all the way down, then halfway up instantly, then back down again even though it's up to operating temp, etc. So I went and bought a new sending unit today and attempted to install it while I changed the thermostat.

So after researching it, I was pretty sure I found it.

Standing in front of the runner, looking at the front of the motor, isn't it under the radiator hose and the upper intake. There are two connectors on the front of the motor attached to plugs, one brown, one green. Isn't the temp sending unit the green one? Problem is what I bought at the parts store isn't the same. The part that threads in looks comparable, but the end of the one I bought just has a blade with a hole in it. The one I pulled out has a green plastic connector that plugs in.

I can post a picture of the one I bought today if it helps.

Anyone have any input?

two pin sensor is for the EFI, also called coolant temp sensor.

temp gauge sender is a single pin, for almost all old Toyotas.

Not sure where it lives either, I haven't looked on a 22RE.

HTH.

The temp sending unit is either on the upper water neck or very close to it on the intake manifold, the sensors your looking at below the upper radiator hose are the water thermo sensor, the computer uses that sensor to know the engine water temp, and the other sensor is the cold start injector time switch, it operates the cold start injector. neither of these are for the temp gauge.

Thanks guys! Now I know I definetly was looking at the wrong location. Anyone sure where the right location is?

on the 22r, 1 of the 2 thermo sensors next to each other hooks up to a heater on the bottom of the intake manifold and heats the bottom of the manifold and cut out when the engine reaches operating temp. more than likely your problem is a loose connection in the gauge itself.

On my 2 22REs, the sensor is located on the thermostat housing.

That severe "up & down" movement sounds more to me like a bad wire. Hit a bump... grounded properly. Another bump later... gauge falls again.

I found that pulling the water-proof engine compartment plugs by their wires is a bad idea. :hillbill: Hadany plugs undone around their recently? Might have to redo some wiring.

not exactly sure on the 85 22re, but on an 88 and 91, the sending unit for the gauge is on top of the manifold between #2 and #3 cylinders, above the coolant pipe that supplies hot water to the heater core. Some people have reported a sending unit on top of the thermostat elbow but there is some confusion as to what that's for.

as myyota mentioned, the two sensors on the front of the manifold, below the thermostat elbow are the cold start time switch (the brown or black one) and the coolant temp sensor (green one) for the ecu.

Mine used to do something very similar - '88 4runer swapped in SR5 cluster - but it'll go to the normal oper temp position when it's cold, I can hit the top of the cluster (or run over a curb) and it drops back down - I actually took the cluster apart and pulled out the gauge itself, cleaned up all the contacts on the plastic circuit board (under the brass nuts that hold it in) with a pencial eraser and it's been fine since . . .