Just had my heater core, evap core and expansion valve replaced a friend of mine helped me with it, after we got it back together 2 days ago, today i was driving it, it reved the transmission up and check engine light came on and it would not upshift at all, drove home at around 15mph. After I disconnected the neg terminal to reset the ECU the car shifts fine what would cause it? Could we have something not connected up?

Thanks guys any suggestions are helpful.

 

You were somewhat around the ecu/tcu but not sure how anything would have happened.

Since you reset the codes (by pulling the cable), then there isn't anything really solid to go on...if it happens again, get the codes (if you are not sure how to do this, check the Common DIY Threads sticky at the top of this section for a how to).

 

Could the TCU cable be loose? Im at a loss, I would think the transmission is okay since after resetting the ecu the car shifts okay and only check engine was on not the D4 blinking. How hard is it to get at the TCU my friend is more the mechanic guy but if its just a matter of ripping out the cd player area that shouldnt be a prob for me to tackle

 

? Hard to say. The ecu or tcu detected an issue. I'm trying to think of what "might have" happened with the heater core replacment..drawing a blank right now.

If it comes back. PLEASE get the code(s) before resetting.

 

If this helps my friend disconnected my alarm would that have anything to do with it? I checked the ECU 15amp fuse everything was okay on that, disconnected the MAP TPS and other sensors and reconnected, so far its not throwing the code after i stomp on the gas trying to get it to replicate, could it have solved itself? Somewhere on the internet i found that only the MAP 02 TPS and a coolant sensor can cause a limp mode is that true also

 

I don't think the alarm had anything to do with it....if it hasn't come back, call it good.

Again, if it does come back, try to get the codes before re-setting.