2007 Saturn Ion III Problem
 

Hello Saturn Enthusiasts,
I just joined to try to diagnose and fix an issue that has been intermittent the past few months.

My car temperature gauge intermittently does not work (goes all the way down past the cool mark) and when this happens, my AC does not work. The strange thing about this is that it goes off for multiple days at a time and then out of the blue starts working whenever I am in the middle of driving, then my AC works.

I have gotten the ODB code and it is P0128 - Coolant temp is always low (see attachment Error Code.png). As such, I checked the coolant (good level) and I changed out the engine coolant temperature sensor. This has not fixed my issue.

It also seems that if the temperature gauge is not working, then I can disconnect the car battery for a short time, reconnect and it starts working for an indefinite amount of time until the next intermittent issue.

Anyone have any ideas?

Thermostat been changed? Sounds as though it's stuck open....

Welcome to the Forum.
Please stop by the New Member section and introduce yourself.


If you plan on staying, go into the User CP at the top right (in the drop down by your username) and create a signature with your name and cars so we can help out in the future as well without wasting our time trying to figure out what car you have.




And onto the Ion. They really are beautiful cars.
Swap the thermostat as stated above. I have an extra one I can sell to you cheap, if you want to go that route. I do my business through paypal.
Also, the notorious COOLANT message. Ahhh, so much fun.
You need a new coolant tank. The sensor went bad, but the issue is it is built into the tank, so you cant replace just that.
I got mine from a junk yard for $5. I know that's a gamble, but its held up for I want to say a year now.
Post some pictures. I love Ions. Really, I have 3 1/2 of em.

Doesn't sound like it's running cold to me -- sounds like flaky ECTS or wiring issue. However the part that doesn't fit is that a battery disconnect brings it back to life.

bbjones---does the battery disconnect work 100% of the time?

goalie -- are there two different ECTS's on an Ion? I certainly believe you about the one in the tank, but bbjones said he already replaced the ECTS, so I'm confused.

bbjones--did you already replace the sensor with tank?

Not that I know of.

bbjones---does the battery disconnect work 100% of the time? - I would like to say yes, but there was one time that I disconnected it for just a couple of seconds and it did not work. However every other time (~5 times) it has brought the gauge back to normal working condition. Does this reset the on board computer system?? I too am curious as to why this seems to work.

I replaced the ECTS close to the engine. I was not aware there was one in the tank until just now.

Thanks for the feedback. I will try to reply ASAP, however I will be at work and unable to reply for the next ~10 hours.

Thanks,
Cory

The thermostat has not been changed, due to when the gauge is working, it works flawlessly. I can try this route, but did not think it was the thermostat after talking with a few individuals at work.

Thanks for the advice.

Thanks for the advice on a new coolant tank. I will replace the thermostat per tooter1 and your advice as well as look into a replacement coolant tank.

Nobody thinks it could be the body control module? That is one of the only things that makes sense to me as to why a battery disconnect / reconnect would work. I will try the battery trick more as the intermittent issue shows up to make 100% sure that a long disconnect brings the temp gauge back to life.


Thanks,
Cory

BCM will have no effect on items engine related. It's a BODY CONTROL MODULE. I know you're asking because of the gauge, but it's not a part of the cluster either.

Battery Disconnect / Reconnect
 

It turns out my work did not block this forum :). So...


I left this morning and was driving into work and my temp gauge was working. However, about 10 minutes into the drive, it stopped working - as did my AC.


Once I got to work, I disconnected the battery for about 30 seconds and then reconnected it. I then started the car back up and the gauge / AC started working again.


Let me know if you have any other ideas besides replacing the thermostat / coolant tank.


Thanks,
Cory




Edit: I would like to mention that the temp gauge/AC does not work about 70-80% of the time. So, the hot season is fastly approaching me in the panhandle of Texas and I would like to get this fixed so my AC works :).

BCM controls the inside of the car like charlie said. And nothing would be working if it was bad.

Some stuff can work w a bad BCM but usually it'll go haywire as a function of time, with more things freaking out. So likely not the issue.

Sounds like it may also be heat related if it takes 10 min of driving after a reset to occur.
Check the tank ects sensor for resistance when it's cold and working, when it's hot and working, and when it's not working.

Also, check the ects connector for corrosion and connectivity to the wiring. Flex it around while measuring DCV (car on) and see if it drops out to 0. Should be about a 5V DCV signal (usual design) so you won't get zapped. I don't have an Ion so I don't know the exact V drop across the sensor, but 5V is pretty standard for such devices.

Thanks for the tips, derf. I will check those tonight.


Is the following video sufficient in describing how to check the voltage of which you recommend above?: https://www.youtube.com/watch?feature=player_detailpage&v=bPAIFL8VH9w#t=10 8


One extra tidbit of info is that it can stop intermittently (after 10 minutes), but then it can start backup when driving for 30+ minutes as well. Sometimes it stops and starts again on the same trip.

yes that's pretty much it. you can use resistance for the continuity check---it should be < 0.5 ohms.
Touch your two meter leads together in the ohms setting to measure the resistance of the meter + leads and subtract this offset to calc your values.

Transient nature of all of this really points to bad sensor or wiring/connector issues in my opinion.

Cold Sensor around 2000 ohms
Hot sensor in the hundreds of ohms I believe.

NO NEED TO REMOVE SENSOR.

I finally have a break in the schedule and am getting to replacing the thermostat and coolant tank/ECTS today. I will also be performing the derf recommended tests of the continuity / voltage.

congrats on passing the 10 post mark!

BBJones,

What ended up working for this temp gauge issue. I have a 2007 ION 3 Quad Coupe with 250,000 miles on it and the same issue just started. I have replaced the CTS on the engine as well as the T-Stat a few years back but I have never replaced the Tank. My gauge starts working again whenever I remove the ECM/TCM Fuse and then put it back (Reset basically I am assuming). Curious if the tank did it for you.

You'll have to timewarp back two years to find out.

Maybe pm the dude and hope his settings are set to notify his email when he gets PMs.

If you do get a hold of him, please ask him to post the resolution, or would be cool if you could do so when you get yours straightened out.

So many people stop by, get advice disappear and we regulars never know if we were right or wrong. We generally assume we were close or they would have asked more questions.

Just annoying how many people can't take 30 sec to say yes that was the problem, or "thank you"

We attribute this directly to their mothers and a poor upbringing regarding manners.

Yeah I agree, doesn't take much to help someone out. I will definitely post the final solution once I figure it out.

Cool,

Thanks Satan

My wifes care has this issue. First the coolant level sensor started going intermittent, then the coolant temp sensor started. I replaced both 2 weeks ago and both are still intermittent. There has to be a bad connector or something somewhere, hard to find.

Temp gauge not working
 

I have a 2007 Saturn ion that the temp gauge on the dash is not working I have already replaced the thermostat and the ECTS and when I disconnected the battery it all was working good and then the gauge went out again.... I have read through some of the posts in this forum about this issue and I saw something about the coolant tank has a sensor also !?!? I didn’t now that what I do need to know is if the sensor in the coolant tank will cause the check engine light to come on.... I do have heat and ac works fine but the temp gauge won’t work.... any suggestions?

Coolant tank sensor will flash coolant on the display when its bad. Thats just the level indicator.
start tracing wiring. Something is nicked somewhere

SES light on?

Go to AutoZone or similar and get codes read for free. Post the codes Pxxxx where x is a number, NOT what the AZ person says they mean.

2007 saturn ion coolent light
 

I to have coolent light on dash, temp gauge drops below line, and ac does not blow cold air.I have had this problem for a couple years now. I disconnect battery for few seconds and it all works as normal umtil next time might be 20 min might be couple days. I have replaced sensor on motor, the reservoir tank witch comes with sensor built in,(dumb idea) and thermastat a couple times with no improvement. No one seems to know what the problem is. Everyone tells you to replace thermastat, tank and sensor, and sensor on the motor but that doesnt fix problem.The car doesnt heat runs fine and i never have to add coolant. 😡

07 saturn ion coolent
 

Some one also said something about transmission oil runs through tank built into radiator and could be leaking mixing the two causing it to have these problems. I would think you would notice it on the dip stick or in the reservoir. I havent noticed it in either.

I don't know about Vues, but I DO know if the trans fluid was mixing with coolant, you'd definitely know it by your replies. Good luck with the Vue. The more I read about them, the more I know I don't want one.

It's an Ion.
1) What color is the coolant in the expansion tank?

2) Have someone put a code scanner on it.(not just a code reader)
The body control modules control most everything on the car except the engine stuff.
This includes the dash. With seemingly random issues fixed by "rebooting" the car's computers, this may be a BCM issue.

Does the coolant light come on at exactly the same time the temp gauge drops?

I am having this same exact issue.

Per my comments above, see if you can get a hold of a true code scanner and not a code reader. Code readers will give you only the powertrain diagnostic trouble codes, Pxxxx where the x s are numbers.

Other modules in the vehicle throw error codes which are stored in the car's computer but these errors do not light up the service engine light. To read that these codes, you need a true code scanner.

You're looking to have body control module scanned for codes. This may indicate what is behind the drop in the gauge reading. The gauge is likely reflecting actual behavior or shall I say reading of the sensor from which temperature is inferred. It seems as though the calculated temperature gets sent not only to the PCM but also to the BCM and is used for multiple things. For example the temperature gauge and, by inference, there seems to be a default behavior built into the logic that controls the AC.

If the sensor is temporarily going open circuit or the wiring 4 that sensor loop is going temporarily open circuit, that corresponds to and inferred temperature reading of -40. The climate control system programming in the BCM probably has a lower temperature limit below which the AC cannot be engaged which also means it will be disengaged if it is receiving a reading below whatever the limit is.

The other possibility is that this is not related to the actual temperature sensor circuit but may actually be an internal issue with the BCM losing the signal being fed to it. I would think it updates every so often everything on the dash. However if it loses its data then the signal going to the temperature gauge will likely go to zero. Pulling the fuse resets BCM which then works just fine until the BCM memory gets somewhat scattered.

As multiple people have indicated above, they changed coolant sensors, thermostat, excetera and it just does not solve the issue.

Which is why I now believe this is likely a BCM related issue. The BCM drives the dash. The temp gauge is on the dash. The reading for the temp gauge should directly correspond 2 the inferred temperature data that the BCM receives as a function of time. If that is not occurring, either the BCM is not getting the data are the PCM is getting the data but is not processing it properly which leads to other side effects.

There are decent code scanners that are blue tooth based andtand of vourseccourse code scanners. For a little over $100 you can get a very nice set up on the Bluetooth side. I don't own a corded scanner so I have no idea what a decent one costs nor brands to stay away from.

Or you can take it to a trusted shop and cough up the $99 for a diagnosis. Some service folks will freely give you the codes, some will hold them hostage, so ask up front if they will provide you the codes or you will be no further along.

Let us know how it goes.

So like what happened?

Sorry for the huge delay in this, but I ended up not figuring this issue out and cutting my losses and selling the ION in July ish of 2016.

Mr Jones,

Welcome back, sir.

Thank you for your update.

I was actually nagging the clown that necro posted onto the end of your post. I have grown quite tired of giving advice two people who request it that do not have the common decency to post either answers to questions nor whether they have or resolve the problem.

Again I am not talking about you. You just came back and answered and for that I thank you.

Feel free to stick around and post in the off topic section. We could use a little hapless banter