Q: Replaced a motor in a 2001 Nissan Maxima and won't crank.

Hello:

Anytime you swap out a motor, it’s incredibly important to double check that all components correctly align and are compatible. The truth is that without being there to physically inspect your Maxima, it’s impossible to diagnose why your engine won’t crank. In most cases it’s caused by the starter and flywheel not fitting correct, an electrical or ground issue or damage to ignition system components. The best advice we can offer is to have a mobile mechanic complete an engine is hard to start inspection so they can help you diagnose the root cause of this issue.

Hi there. Assuming, the replacement engine is capable of turning over, the battery should be fully charged. The battery cable connections need to be clean and tight. Disconnect the starter signal wire, using a test light probe the wire terminal, while an assistant turns the key to the crank position. Test light on, it’s likely the starter is at fault. Test light off, it’s likely the neutral safety switch is at fault or out of adjustment. There is a possibility, the starter relay or ignition switch is at fault. Proper diagnoses needs to be performed. I recommend having your vehicle’s no crank be diagnosed and repaired by a certified technician, such as one from YourMechanic.