having this recurring problem of code 20 ... switched out wiring harness numerous times to no avail ... anyone whos experienced this same code please leave a note letting me know what the problem was and how you fixed it
thanks

 

make sure the is a green/red wire in pin b19 on the ecu.

 

make sure you dont have corotion on any of your ground locations.

 

did that .... all grounds seem to be ok... thermo gauge shoots up to H in ingition pos 1 only when the key is off ... no head or taillights work .... dome light or hazards cause the same temp gauge prop

 

problem solved .... grounds grounds grounds grounds .... i installed a grounding kit to starter, alternator, block, head, tranny and lights and all of the symptoms went away ..... if your are having the same problem try a grounding kit ... it WILL save your alot of hassle