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