Re: Turns over thendies, gauges go crazy
Welcome to the garage.
Your PCI data bus is dead due to a shorted component. This can be fun to solve, but many times the problem is the crank position sensor which is shorted. Just disconnect the connector from the CPS and see if all other indications/power locks/power windows return to normal. It will still not start, but would be an indication that the CPS is the problem and must be replaced.
Just reading again your post, it can be that a wire is shorted to ground behind the dash, after the replacement of the heater core. maybe a wire got pinched between two metal parts or a screw wnet through the wire isolation.