Please ensure the power cables are clean and show no signs of overheating. Usually, the traction power amp fails because of poor crimps at the cable ends...right at power amp. You must buy the cables as it's crimps are special high strength. Home made crimps will overheat as they cant take the current. If the connector at the power amp was dark and discolored, the new power amp will fry as well! Any trucks with overheated cables and loose nuts on the power amp will need cables asap! Change before the power amp shorts. Always replace the 3 relays (1-100-068) when replacing the power amp.