Temp Gauge Problems

[Department Of Boost]

My OEM coolant temp gauge isn’t working. It “cycles” when you turn the ignition on so the actual gauge seems operational. It’s a brand new sensor and as far as I can tell its plugged in (it’s buried under/behind the blower).

My Livewire seems to be reading something. When I start the motor cold it reads a temp about ambient. And as the motor warms up the Livewire shows a higher reading, but its not proportional to the actual engine temp. When the actual water temp is 160deg the Livewire reads 208-210deg. When the actual water temp is 210deg it still reads 208-210deg.

As the motor warms up the OEM temp gauge doesn’t budge.

If I scan for codes with the Livewire I get nothing? Wouldn’t a malfunctioning or unplugged sensor throw a code?

Any ideers?

Thanks

 

[akula52]

temp gauge

Not sure about some of your symptoms, but if your car is a 05-06 read this thread about stepper motors.. http://s197forum.com/forum/showthread.php?t=50265&highlight=temp+gauge

 

[AbdullaGT500]

I don't think the temp gauges in our cars are actually accurate, it moves when the car gets warmer, but it's not accurate. I could be completely wrong though. Similar to the oil pressure gauge.

 

[Cone Sweeper]

Most temp gauges in cars are not accurate worth a shit.. by the time it moves it's usually already too late and shit is messed up... but to the OP, I had the same problem with my 05, RPM's and the Temp gauge were all wacked out.. ordered new stepper motors and changed everything and no problems since.

 

[1lowtoy]

Most temp gauges in cars are not accurate worth a shit.. by the time it moves it's usually already too late and shit is messed up... but to the OP, I had the same problem with my 05, RPM's and the Temp gauge were all wacked out.. ordered new stepper motors and changed everything and no problems since.

I think he is talking about the datalogged temp and not the cluster. Datalog cylinder head temp as well as coolant temp. That sensor in the head is cylinder head temp sensor and not coolant temp. Coolant temp is an inferred reading and not an actual water temp reading.

 

[Department Of Boost]

I think he is talking about the datalogged temp and not the cluster. Datalog cylinder head temp as well as coolant temp. .

Correct, the datalogged temp reading is working but goofy. Ambient reads ambient (cold motor). 160deg reads 210 and 210+ reads......210.

The OEM gauge doesn't move aside from when the key is put in the "on" posistion.

I am also logging actual coolant temps with my data acquisition system at the coolant crossover to compare the other two points against.

I would try another temp sender but my blower and intake need to come off to do it. I'm hoping its not the sensor.

 

[1lowtoy]

What are you getting for cylinder head temp on the livewire?

 

[Kuro!]

Our stock in car gauges are idiot gauges... if they were actually accurate you'd have every soccer mom in the country bringing her car in to the dealer every time their oil pressure gauge was "low"

 

[Department Of Boost]

What are you getting for cylinder head temp on the livewire?

At ambient (cold motor) it reads ambient.

When the water temp is 160deg (read with different gauge) the Livewire shows 210deg

When the water temp is 210+deg (I've run it up to 225) the Livewire reads......210deg.

This is driving me nuts!

 

[1lowtoy]

We are getting our wires crossed. You can log both coolant temp as well as cylinder head temp using your livewire. The s197 ecu uses cylinder head temp to come up with what the coolant temp is. These cars do not have a sensor that is actualy in the coolant stream. I do understand that have installed an aftermarket sender into the stream and are logging that sensor using an analog port on the livewire as well.

 

[Simon]

So here is the problem.

Underneath the blower manifold in the valley of the motor is your Cylinder Head Temp Sensor (CHT) it sticks out and comes within a few MM of the bottom of the manifold. Sometimes the CHT sticks up higher than normal or the casting lets the manifold sit lower or (in my case) the CHT had backed itself out a few turns and pressed it's wires against themanifold causing am intermitant dead short wheich would cause my CHT to go from one extreme to another.

Pull the blower, check the wiring. Most likely it's repairable. You can test it with a multi meter. Put thte CHT back in an put alittle lock tight on it. You should be fine.

The newer CHTs are slightly longer and cause issues. Just be careful of that if you order one.

 

[Simon]

At ambient (cold motor) it reads ambient.

When the water temp is 160deg (read with different gauge) the Livewire shows 210deg

When the water temp is 210+deg (I've run it up to 225) the Livewire reads......210deg.

This is driving me nuts!

That's exactly what mine was doing. And then it would go into failsafe.

 

[Department Of Boost]

I ended up buying a new sensor yesterday and did test it in water to get some resistance readings. It worked.

I was going to rig up a resistor and plug it directly into the harness to see if I could make sure the PCM was getting a 200deg resistance reading. But I went for the a better solution. I cobbled together a bit of harness out of a few connectors and plugged the new sensor into it. Then I dunked it in 200deg water and turned the key on. And bingo! The OEM gauge worked and the Livewire read accurately. So my problem is either the small jumper harness that goes to the sensor or the sensor. So the blower has to come off…..but I’m not going to do that.

I ordered that small jumper harness ($11) yesterday and I am going to put the new temp sender right in the coolant crossover where I already have a plugged hole. At least until the blower has to come off next time. It will be reading actual coolant temps, theoretically at the hottest part in the system (just before the T-stat) so I doubt it will be a big deal in regards to reading the temp correctly.

What’s odd is that the Livewire was getting a reading with the “bad” sensor, but a strange one. And the gauge didn’t move despite the Livewire reading 210deg which should have had the gauge well up in its range.

I was reading in the manual, and keep in mind I was skimming so this is not verbatim. It seems that if the PCM senses that the temp signal is not there it will calculate its own temp signal based on the IAT readings and a few other inputs opposed to going into “lip home mode”. I think that is what the PCM was doing. It makes sense because the readings I was getting on my Livewire were fairly proportional to what the IAT was. But so the “driver” knows it may kill the signal to the gauge. Or something like that.

I hope taking a temp reading from the coolant crossover won't be an issue. I can't imagine it will be. I'm sure the blower will be coming off at some point so I can fix the "real" temp sender but I would rather wait till I have at least two reasons to pull the blower. Those KB's absolutely SUCK to remove even though I machined my own mounting plate with O-rings so I don't have to slather it with RTV which "welds" the blower to the intake. And after you get it off you have an hour of RTV cleanup to do. Sometimes I hate my KB.


Thanks for your input guys!

 

[Charlie Sheen]

Oil pressure gauge is one thing but not my stock temp gauge. I have a secondary gauge reading temp from the cross-over and when it went hot the cluster temp gauge showed the same thing. When the stepper motors are functioning correctly they are actually quite accurate.

 

[TexasBlownV8]

I used a secondary coolant temp sensor, mounted in the coolant crossover just before exit to the radiator on the passenger side of the KB crossover (there's a raised round part on there about the size of a quarter..perfect for drilling/tapping a hole!).

Initially, I used a sensor on the side of the block, but header heat caused the sensor to fail prematurely, causing it to read normal a ambient as well, but it'd read lower than actual temps, being off by about 25* at full engine temp. Was just a bad sensor; so I moved to the crossover it when I replaced it.

I have some pics, just not uploaded/online. Here's a pic where you can see the brass sensor sticking out of the crossover in the upper right of the pic by the alternator and radiator hose.
http://i224.photobucket.com/albums/dd92/texmike_photos/COP-wiring-11.jpg

Oh, and FWIW, the "Ambient Temp" is also a calculated/inferred value. I looked into it, trying to find where/how it's measured. There is NOT a separate sensor for it, and somewhere I found where it said it was inferred (at least in for 2005).

 

[Department Of Boost]

I have a secondary gauge reading temp from the cross-over and when it went hot the cluster temp gauge showed the same thing.

Perfect, good to know. Thanks!

I used a secondary coolant temp sensor, mounted in the coolant crossover just before exit to the radiator on the passenger side of the KB crossover (there's a raised round part on there about the size of a quarter..perfect for drilling/tapping a hole!).

Initially, I used a sensor on the side of the block, but header heat caused the sensor to fail prematurely, causing it to read normal a ambient as well, but it'd read lower than actual temps, being off by about 25* at full engine temp. Was just a bad sensor; so I moved to the crossover it when I replaced it.

I have some pics, just not uploaded/online. Here's a pic where you can see the brass sensor sticking out of the crossover in the upper right of the pic by the alternator and radiator hose.
http://i224.photobucket.com/albums/dd92/texmike_photos/COP-wiring-11.jpg

Oh, and FWIW, the "Ambient Temp" is also a calculated/inferred value. I looked into it, trying to find where/how it's measured. There is NOT a separate sensor for it, and somewhere I found where it said it was inferred (at least in for 2005).

Good stuff, thanks!

I was heat cycling the car yesterday and the OEM gauge started working on and off....mostly off. I did a wiggle test of everything I could touch but no joy. What a PITA! Now it's just teasing me! Looks like an alternate sensor location is still in the cards. I need to stop by the dealer today and pick up that little bit of harness I ordered.

Its always something

 

[TexasBlownV8]

Yeah, as mentioned, the stock gauges are mostly just "idiot lights" in the form of gauges. Oil pressure definitely is like that. But the signals to the instrument cluster are sent from the PCM to the cluster through the CAN bus; no separate wire from each sensor to the gauges. So if a specific gauge is messing up, it's most likely the step motor in that specific gauge.

And yes, it IS always something when you have that many mods!

 

[Simon]

Those KB's come off pretty easily. Checking the wire underneath would do it or you could get a scope and look through the back of the blower. I did that and saw the problem.