Been having alot of trouble with my heater not working.Was just getting a very little bit of luke warm air.The temperature gage always acted weird.It wouldn't move for a long time, and then after you go a few miles it would go way up to about 250 degrees, and then drop right back to 200 and stay there. Had the heater core and hose's flushed.Also had thermostat changed. This was done about a week ago.Well now i have no heat at all and my CHECK ENGINE light came on and will not go out. Anyone have any ideas what could be the problem? Thanks for your help!

 

Was the thermostat changed by a reputable shop? Sounds to me like the first one went bad, and the second one was installed backwards, which would seriously limit the coolant flow through the engine. The check engine light would likely be due to overtemp if that were the case....

 

have a shop read the codes on the computer....that is a good way to see whats going on. The temp sensor that runs the guage is not the same sensor that sends temp to the computer.

 

i bought one of those code readers on ebay. pretty cheap and will at least give me an idea of what's going on without buggin one of the techs @ my shop.

 

My husband put the new thermostat in. He said he put it in the exact same way the one he took out was.

 

Thanks for letting me know about that code reader on Ebay.I am going to look for one.

 

you can try the key on-off-on-off-on to get the codes out, this works for most trucks, either the codes will come out on the odometer (for '96 & newer trucks) or the CE light will flash the codes out.

sounds like you might have 2 problems to me... a stuck open t-stat or the flap for fresh air is stuck and or broken. the other being that you might have a bad temp sending sensor causing the temp to jump to 250 deg, then back down. you can check that by pulling it out and measure the resistance as it sits in water as you heat it up. a short I think will read max temp.

 

According to the Haynes service manual I have (becasue Chrysler is out of their MIND and wanted $185 for theirs), the key trick only works on '94-'97 models with an OBD-I computer system. Some 96 and all later had OBD-II computers, which the book claims ya need the scan tool to plug into the diagnostic connector under the dash.

In my experience with GM products, the "scan tool" is nothing more than a simple circuit which connects two pins on the diagnostic plug together through a resistor, which then makes the computer go into some kinda diagnostic mode and the check engine light flashes the codes.

I'll admit to being cheap - I'm not gonna pay $50 (or even $10) for a shorting plug in a fancy case. Is this the way the Dodge OBD-II works, and if so does anybody have a schematic of the circuit?

Mike Bishop
www.flbullrider.com

 

Nevermind, thanks to Steve's Christmas post, I now know the inner workings of the Data Link Connector

 

pretty much..if you got a digital odometer..itll work..regardless of year make model... its ODBII witch is the actualy ONLY stardard system that is put into EVERY single car sold in the US and most overseas... so it will work and save you time and sometimes money..