My engine will not crank over why?

This sounds like the starter is having problems or the battery needs to be load tested these guides can help us fix it.

https://www.2carpros.com/articles/starter-not-working-repair

and

https://www.2carpros.com/articles/car-battery-load-test

Please run down these guides and report back. My first thought is a failed starter or you have a bad battery cable that feeds the starter. Both would exhibit those symptoms and still leave the interior alone as they are fed from a different circuit. I would start by cleaning the battery connections on the cables at both ends. Pay close attention to the cables where the terminals attach, I have had more than a few that looked fine but the cables were corroded inside.

First, you must be aware that in the '90s, the industry standard was that a good, fully-charged battery would be able to crank the engine fast enough to start after sitting for three weeks. That was due to the drain from the numerous computer memory circuits. Since then, cars have had many more computers hung onto every concealable part of our cars, so it's unlikely that three weeks is still relevant. What you should have started with was charging the battery at a slow rate for at least an hour. Now that you have a different battery installed, (and you didn't say it was a new one), it sounds like it too is not fully-charged.

Measure the battery's voltage. If it's good and fully-charged, it will be 12.6 volts. If it's good but totally discharged, it will read close to 12.2 volts.

Next, turn on the head lights so current is trying to flow, then measure the battery's voltage again, right on the posts if you have top posts, otherwise, you'll have to skip right to the side post bolt heads. Please tell me what you find for voltage. If you have top posts, now move the meter probes to the cable clamps and measure again. You should find exactly the same voltage.

If you have side posts, we'll have to skip over part of the tests and go right to the starter. Put one meter probe right on the large stud on the starter that the battery cable is bolted to, and the other meter probe on an unpainted surface on the engine block. You'll find full battery voltage at first, but I'm interested in the voltage you find when a helper tries to crank the engine. During normal cranking, that voltage must stay above 9.6 volts. When you have a cable or connection problem, you're going to find considerably lower voltage.

Another clue to a bad cable or connection is the head lights or interior lights will get real dim during cranking.

Get a battery drain test-sounds like something is draining the battery overnite

Just to add to this one you have to get whats called a parstic draw test it will see what the draw on the battery is with everything turned off. Then you have to start pulling fuses to narrow down what circuit the draw is on.I have seen dome lights map lights cargo lights even window switches causing drained batterys. First you have to find the circuit its on then start unplugging things on the circuit to find the drain. Sometimes the drains are easy to find other times there very hard to find.

It sounds like the starter motor has gone bad. I would go over this guide to be sure and if so get a AC Delco unit. Check for power at the trigger wire.

https://www.2carpros.com/articles/starter-not-working-repair

Here is a guide to help you step by step with instructions in the diagrams below to show you how on your car:

https://www.2carpros.com/articles/how-to-replace-a-starter-motor

Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.

Hello,

There is a starter relay that needs to be checked. Here is a guide to help and the location of the relay as well as the starter wiring diagrams so you can see how the system works:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Starter relay - left side of engine compartment, attached to UBEC bracket.

This guide can help as well:

https://www.2carpros.com/articles/starter-not-working-repair

Check out the diagrams (below). Please run some tests and get back to us.

Cheers, Ken

Did you lose all power or did the engine just shut off and won't start?Any codes in the computer?

Is the security light on solid or flashing when trying to start it or with the key in the run position?

What is the actual fuel pressure at the fuel rail?