Coolant Temp Gauge Issue

[DickB]

Hey everyone,

I promised I've searched a ton so forgive my first post being a question and hopefully this isn't something I should have found and just missed.

I just picked up my LX470 last week and got a deal on it since it had a few minor issues (half the third row missing, SRS light, etc, nothing major) so I've been working on getting all that sorted. Found out the CEL bulb was missing and pulled the instrument cluster to replace it, upon reinstalling my coolant temp gauge has been weird. When the car is turned off the needle is in the expected bottom position below C. As soon as the key is turned to on though it jumps up to above C instantly even when the car is cold and not running. When the car reaches normal operating temps its really high just below the red lines. I tried unplugging the coolant sensor and the needle still stays above C with the car on so it seems like something is making the needle start at a higher than normal position so normal temp reads higher than it should. I tried re-seating the instrument cluster but no luck. Is there some trick to seating it properly? Or any other ideas? Pics below of the levels:

Level with the car cold and off but key in on position.

Normal operating temp reads this high.

Thanks for any insight you all have!

 

[LBridges]

I'm wondering if a poor connection is causing too much resistance that results in a bad gauge reading. I don't know that my idea is your problem, but I can say I pulled my dash panel out and had to remove and reinstall (I think) three times before everything worked as it should. I'd like to blame it on the design, but more likely the fault was mine.

 

[DickB]

Ya the first time i reinstalled i got some weird lights and reinstalling a second time fixed all but the temp gauge. Tried that three more times and no change. ECU still reads the correct temp though so not sure where the mix-up is happening. Thanks for the ideal, i'll try the install/uninstall a few more times.

 

[nissanh]

Make sure the engine is not running hot, use an IR thermometer and check the upper hose temp.
Did you remove the front plastic cover to access the gauges? If not, I'd say run few days. Things will come back to normal. I once had the ignition on just to get the sunroof closed and turned the ignition off. Then I started the truck and fuel gauge did something crazy: showed half a tank at one time then a quarter etc. , even reserve ligth came on. Drove above 20 miles and everything went fine.

 

[DickB]

Make sure the engine is not running hot, use an IR thermometer and check the upper hose temp.
Did you remove the front plastic cover to access the gauges? If not, I'd say run few days. Things will come back to normal. I once had the ignition on just to get the sunroof closed and turned the ignition off. Then I started the truck and fuel gauge did something crazy: showed half a tank at one time then a quarter etc. , even reserve ligth came on. Drove above 20 miles and everything went fine.

I sure hope that is the case. I just reinstalled the cluster again and now the fuel gauge doesn't work like you mention and me speedometer doesn't work along with the existing temp gauge problem. Seems like it is getting worse rather than better.

 

[flintknapper]

Dick,

When you disconnected the temperature 'sensor' was it grey or green? The sending unit and TS are right there together and do different things.

You might have a bad sending unit or a corroded connection.

 

[DickB]

Dick,

Did you disconnected the temperature 'sensor' was it grey or green? The sending unit and TS are right there together and do different things.

You might have a bad sending unit or a corroded connection.

I disconnected the green plug. Easy enough to replace the sending unit I suppose, it just seems odd that this only started after I removed/replaced the gauge cluster and that the ECM is still getting accurate readings.

 

[flintknapper]

I disconnected the green plug. Easy enough to replace the sending unit I suppose, it just seems odd that this only started after I removed/replaced the gauge cluster and that the ECM is still getting accurate readings.

Yes, I agree.

If you have some way to check (maybe you already have) what the ECM is reading (via a scanner) then we know the temperature sensor is good. But the sending unit (sends the signal to your gauge). It is unusual for the gauge itself to be at fault, so double checking the connections/wires there needs to be your first step (again ).

If you find nothing there or that does not correct the problem, then look to the sending unit and its connection. The grey unit. It has a single pin connector. There is a white plastic insert in it that gets brittle and if missing (from previous disconnection) doesn't allow for good alignment of the connector pins. Its an easy part to damage when removing the intake for a starter replacement, if that has been done on your vehicle.

Don't you just hate electrical gremlins!

 

[DickB]

Yes, I agree.

If you have some way to check (maybe you already have) what the ECM is reading (via a scanner) then we know the temperature sensor is good. But the sending unit (sends the signal to your gauge). It is unusual for the gauge itself to be at fault, so double checking the connections/wires there needs to be your first step (again ).

If you find nothing there or that does not correct the problem, then look to the sending unit and its connection. The grey unit. It has a single pin connector. There is a white plastic insert in it that gets brittle and if missing (from previous disconnection) doesn't allow for good alignment of the connector pins. Its an easy part to damage when removing the intake for a starter replacement, if that has been done on your vehicle.

Don't you just hate electrical gremlins!

Sorry for the late reply I've been out of town. So are you saying there are two sensors, a Temperature Sensor and a Sending Unit? Or are they the same thing just two names? The ECM is currently reading correct/normal operating temps but the gauge is still reading high. I wasn't sure if the gauge got the signal from the ECM or directly from the unit. Either way when I unhooked the unit right above the thermostat i got the CEL for a malfunctioning temp sending unit but did the gauge still read around 25% (like in the first pic)

 

[flintknapper]

Sorry for the late reply I've been out of town. So are you saying there are two sensors, a Temperature Sensor and a Sending Unit? Or are they the same thing just two names? The ECM is currently reading correct/normal operating temps but the gauge is still reading high. I wasn't sure if the gauge got the signal from the ECM or directly from the unit. Either way when I unhooked the unit right above the thermostat i got the CEL for a malfunctioning temp sending unit but did the gauge still read around 25% (like in the first pic)

You have PM

 

[Rolocado]

I replaced my D light bulb and when I re-enstalled mine, all of my gauges we effed up. I kept tightening the screws and they all went back to the way they should. I might guess that all the pins in the connectors aren't hitting right. They seem finicky. Pull it out, put it in straight and tighten more and see if it works?

 

[DickB]

I replaced my D light bulb and when I re-enstalled mine, all of my gauges we effed up. I kept tightening the screws and they all went back to the way they should. I might guess that all the pins in the connectors aren't hitting right. They seem finicky. Pull it out, put it in straight and tighten more and see if it works?

Thanks, this actually did resolve all my issues aside from the temp gauge. Seems like a poorly designed way to connect everything, I was timid about tightening things too much since i didn't want to strip the plastic

 

[flintknapper]

Thanks, this actually did resolve all my issues aside from the temp gauge. Seems like a poorly designed way to connect everything, I was timid about tightening things too much since i didn't want to strip the plastic

A light coat of dielectric grease can sometimes aid an otherwise poor connection, but where you have multiple pins be careful not to apply so much as to 'bridge' the different circuits together.

Hope you find the source of your troubles soon.