In which case, begin the investigation with the Starter relay (s1) and Ign 2 circuits.
Ign 1 and keyed Accessory should not be connected to power when the key is in Start, only the two circuits needed for starting.
have someone hold the key in start and check for shorts to ground.
You can also check the connections from the battery line to the S1 (yellow) and the Ign 2 (brown). They should be zero.
