Hey Scotty I love what you do and my question is 2003 Nissan Murano hooked up the battery backward and I checked all fuses the ignition relay is bad or at least I have to manually press it to crank the car but it wont start everything was fine before this blunder what steps do you suggest and also p1001 air flow sensor is showing not sure if that would prevent starting as you can tell all I truly know about car repairs is what I've learned from your videos please help if possible
So many computer modules can be fried by hooking the battery up backwards it would make your headspin. But pray you can find blown fuses and or melted small wires and that you don't need computer modules but you probably will
Could have fried the computer if the main ignition fuse didn't pop.
Well, somewhere there should be a diode across every relay coil. Any that received power backwards would most likely fry these diodes (most burn open but some could short too). This is for a protection circuit to prevent reverse voltage spike being induced into the system when the relay is de-energizer. I'd start with the electrical service manual and look at everything "hot all the time" went too first. If you didn't turn the key on with battery reversed, you've increased your odds of there being less failures. GL
