Immobilizer Intermittent? Engine Not Cranking Over?

I think your security system is messed up and the only way to check is with a pro scanner that most mechanics have, the old battery could have caused some of it, but putting a new battery in normally engages the security and it may not happen immediately. Have a pro scan it to see if it is security or another problem it does not need to be a dealer to do this.

We need to determine if your vehicle has a battery sensor on the negative battery terminal of the battery.

This is used to determine the load on the battery so that it knows how much to duty cycle the generator. In other words, when all the accessories are turned off the draw on the battery is low and so the voltage regulator is duty cycled low. When you add the accessories the duty cycle should go up so that the voltage regulator puts out a higher voltage. The fact that it is dropping when you add the accessories back in, show that the regulator is not increasing the output. This is either due to a faulty regulator or the battery sensor is not accurate.

You can verify this by monitoring the voltage in the BCM with a scan tool.

Let me know what questions you have. Thanks

It has to be scanned first then go from there it may be a simple or minor problem. If the ignition switch is messed up could be causing this, but after install it has to be programmed to truck anyhow.

Hey David,

Good to hear the problem is fixed! Please use 2CarPros anytime.

There are a number of reasons that this happens. See the attachment for the list of inhibit events. Basically there is one of these that is causing the remote start from starting the engine.

There is no easy way to know which one other than checking each of them. Let me know if you have questions. Thanks

Can you hear the fuel pump run in the tank for 5 seconds when the key is turned on with cranking the engine over? If not lets check the fuel pump relay. Here is a guide to help test the relay with the location below.

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

This guide can help as well

https://www.2carpros.com/articles/car-cranks-but-wont-start

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.

Hi,

It could be the starter. Let's check a few things first. There is a 40amp starter fuse in the under hood fuse box. I did my best to help you locate it. If you look at pics 1 and 2, they show the wiring schematic (pic 1 and highlighted) and pic 2 ( highlighted the fuse). See if the fuse is good. If it is, confirm there is power to and from it. Here is a link to help with that:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

If it checks good, switch the starter relay with a different one in the box having the same part number.

If that doesn't change things, we need to see if the starter motor is getting power. On the starter, there will be a heavy gauge wire that always has 12v right from the battery. There will a smaller gauge wire that should have 12v when the key is in the start position. Have a helper turn the key to start while you check the smaller wire for power. Here is a link to help you check the starter:

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

If it does have power, replace the starter. If there is no power, let me know.

Here is a link the explains in general how to replace a starter. You can use it as a guide.

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

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Here are the directions specific to your truck for starter replacement. The remaining pics correlate with the directions.

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2015 Chevy Truck Silverado 1500 4WD V8-5.3L
Starter Replacement

Removal Procedure

Disconnect the battery negative cable.

Raise and support the vehicle

Remove the terminals from the starter solenoid. Note: The battery must be disconnected before doing this.

pic 3

Generator Battery Control Wiring Harness Remove

Electrical connector (3) disconnect

Starter Heat shield (3) Remove
pic 4

Starter mounting bolt remove

pic 5

Installation Procedure

Install starter

pic 6

Starter Mounting Bolt install and tughten to 37 lb ft
Starter Heat Shield (3) Install

pic 7

Generator Battery Control Wiring Harness (2) Install

pic 8

Battery positive cable nut (1) starter solenoid install and tighten to 80 lb in

Electrical connector (3) connect

Connect the negative battery cable.

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I hope this helps. Let me know if you have other questions or need help.

Take care and God Bless,

Joe

If it just clicks then this is could be the starter but if the light is staying on then we need to check codes to find out if there is another issue.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

However, here is another guide that will help with this if it is a starter issue:

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

I attached the wiring diagrams below for us to check voltage at the starter as well if we get to that point.

Basically, i think we need to start with codes and go from there. Let me know what questions you have. Thanks

Was it running rough and the light blinking before you had it there? If it was not doing any of this and he changed a coil pack then I suspect either he left something unhooked or the coil pack is not any good. The fact that he replaced that coil and that is where your misfire is, tells me it is one or the other especially if it was not doing this before it went in.

Let me know this and we can go from there but I would be taking it back ASAP.