Volvo 7.4

[Dwight Hugh Cook]

I have power to everything but when I turn the key to start the engine there is no power to the switch or starter, is the selinoid bad or the switch

 

[AllDodge]

You have power to the red/purple wire at the key, but when you turn the key ON all power is gone, correct?

What is the voltage reading at the Battery and at the Key?

If this is correct start at the Battery and start cleaning the cables at both ends until every thing is shinny metal. Next go to the Bat switch if there is one, then move to the Starter. Don't forget to do the negative cable end that is attached at the rear of the block