issues after changing heater core

houstonhomer

New member
just performed the dreaded heater core swap last night. Got everything put back together and put some coolant flush in the system. went for a drive today. Truck wont boost over 10lbs. speedo not working, and the check engine light came on. Thinking its something to do with disconnecting/connecting the ECM. Either way im no electrical pro, any help guys would be awesome. Also check engine light goes off after you shut the truck off, but comes back on in five minutes.
 

Don W.

Stab it and steer it
Re: issues after changing heater core

Thinking its something to do with disconnecting/connecting the ECM. Either way im no electrical pro, any help guys would be awesome.

No doubt. Just pull the thing back down and check all connections, plugs whatever. But before you do that reset it by pulling the ECM fuses, wait 20secs or so, reinstall and see what happens. If same prob check ECM connections with fuses pulled or bat disconnected.
 

KDBL1TY

Member
Re: issues after changing heater core

X2 unplug and replug ecm. Double check connections for moisture.I dont recall having to remove my ecm to replace the heater core. Check the connections with to the timing wire.
 

CalgarySS

1000 miles and counting..
Re: issues after changing heater core

Right on Houston, glad you got it figured out.

I will be doing the heater core on #1907 here soon.

How long did it take you to do?
 

TY0618

Member
Re: issues after changing heater core

Right on Houston, glad you got it figured out.

I will be doing the heater core on #1907 here soon.

How long did it take you to do?

When I did mine it took me 45min. including clean up! I have changed heater cores in many Jimmys and Blazers. I also did the one in my TY. The first one I did took me an hour and a half.
 
Top