Temp Gauge Not Working, What could be wrong? Options

[Nartanian]

So after a year, my Celica officially runs good as of today. Only problem is my temp gauge reads cold. I think everything is hooked up. I think my sensor is hooked up right? Not sure...




I found a cord in the back that was not hooked up though. I don't know where it goes...



This plug *edit: this plug goes the egr*



Any input will greatly be appreciated since winter is on it's way.

This post has been edited by Nartanian: Oct 7, 2009 - 4:55 PM

[bccentaur3]

shouldnt there be more than just one plug on the coolant neck? check that. you might have to take the dizzy off to see.

[Nartanian]

Ok, I'll check 1st thing tomorrow. I'm gonna assume it's plugged though because I don't have any spared adapters or lines unplugged besides the one I showed in the pic.

[trdproven]

temp gauge sensor is near the coolant inlet to the engine.

[azian_advanced]

if the sensor is unplugged, you should be getting a CEL. i think it's that grey plug in the first pic but i'm not sure i've never seen an ST before. but if the gauge is constantly reading cold, then either the sensor or your cluster gauge is messed up.

[Nartanian]

This morning I double checked all the wiring and everything is plugged in. I found out that the missing wire that was hanging in the picture goes to the egr, so that has nothing to do with the temp gauge. I'm sure the cluster works just fine because prior to starting the car the needle moves up a bit. I have not reason toe believe the cluster is faulty. What I also did this morning was replace the temp sensor I believe. I unscrewed the 2 nut that hold the thermostat housing to the head and replace that thing in there. I lost quit a bit of coolant doing that. I don't know if I put it in right though because I didn't replace the rubber seal around it, and it was a little loose too. I just cramped in the sensor as best I could and tightened the thermostat housing over. It was pouring outside so I was rushing to get it all done. Anyways it didn't help. I don't know if it because I put it in badly or if it's a wiring issue. Hope this helps so I can get some good advice.

[Nartanian]

I gotta feeling this might be the fault. Can anyone veryify if this reads engine coolant temp before I replace it?




This post has been edited by Nartanian: Oct 6, 2009 - 3:34 PM

[Nartanian]

I replaced all the sensors and still no luck... I don't know what else it could be. I guess the cluster is the last thing I need to check?

[Nartanian]

Cluster is out. Everything seems fine. No corroded wires and everything plug. I didn't remove any of the needles though. It's a pain setting it back up. I don't know what else to check. Sensors are good, thermostat is good, heater blows fine... I did notice though that both radiator fans are constantly on even if the motor is cold. If the car is on the fan is on. I don't know what the deal with that is. Can anyone please please help?

[azian_advanced]

check to make sure the radiator fan plugs are plugged in. if they're unplugged, it will cause the fans to constantly run.

[trdproven]

you replaced the sensors? never seen an st so it is either of the two gray plugs you showed, I'm pretty sure it is only one wire though. bfor you buy a cluster swap it out for someone you can borrow from. or you have a cut severed wire along the way. trace it also.

[Bitter]

if both fans are always on then the sensor circuit that feeds coolant temp to the ECU is open. get a wiring diagram and fix the problem correctly.

[Nartanian]

Wow, after all that work, I found the stinkin culprit. There is a plug on the other side of the motor by the water pump. That little sucker was hiding but I found it and plugged it back in.

Moral of the thread:

Always check, check, and check ALL wiring after a head swap (that's right not double check, triple check) It will save you a headache.

I hope this thread helps someone down the road later.

This post has been edited by Nartanian: Oct 8, 2009 - 10:47 AM