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Q: Brand new motor will not start

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My son bought a rebuilt motor from a company on the internet and he has never been able to get it started the only thing i can think of is that when he was putting things back together he had the battery hooked up and had every thing hooked up to the alternator and then dropped it and the sparks went crazy and after that he finished hooking every thing up and tried to start it for the first time and it would not start do you think he fried the computer the only code it comes up with is one that says something about the auto shutdown so I check the auto shutdown relay and fuse the they check out OK are the motors in jeep made different for different yrs I know that some 4.7 have either a 16 tooth or 32 tooth thing on the crankshaft and the motor has the right one on it is there something else that could be different here is the vin if it help 1J4GW48N44C102579 Thanks so much for your help and time

My car has 178000 miles.
My car has an automatic transmission.

A: Hi there. From the description you have pro...

Hi there. From the description you have provided, changing the vehicle engine, shorting the alternator and now a no start, is going to require proper diagnoses. The computer recognizing a fault in the auto shutdown relay circuit, is encouraging, the computer may be okay.

Shorting the alternator could have blown a main fusible link or fuse. The ASD relay may appear okay, circuit tests need to be performed to isolate the loss of electrical power. The crankshaft reluctor ring is the tooth thing, you have referenced.

Since there are so many possibilities. I recommend having your vehicle’s no start condition be diagnosed and repaired by a certified technician, such as one from YourMechanic.

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