No start no crank I accidently shorted the connections to the run-crank relay?

MINNERMP

MEMBER
2017 CHEVROLET SILVERADO
5.3L
V8
4WD
AUTOMATIC
260,000 MILES

I accidently shorted the connections to the run-crank relay in the X50 underhood fuse box and now the truck won/t crank. The run-crank relay is not getting a signal to the grd pin to activate the relay. If I hold the relay closed the engine will start with the ign key on but will not shut off with the key until I release the relay. I apparently shorted something but not sure what

Wednesday, August 17th, 2022 AT 8:11 AM

9 Replies

KEN L

MASTER CERTIFIED MECHANIC
54,144 POSTS

The first thing to do is check all fuses. Here is a guide to help and the use location in the diagrams below. Also, check the BCM fuses with the key on.

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

If all fuses are okay, we need to do a CAN scan which is easy. You can get a CAN scanner from Amazon for about $30.00.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

If the BCM is bad here is how to change the BCM out in the images below. Let me know what happens.

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Thursday, August 18th, 2022 AT 9:25 AM

MINNERMP

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6 POSTS

I checked all the fuses, and they all check good and my Innova scanner has no trouble connecting. So, I’m not sure why the run crank relay, the start relay, and the fuel pump relay are not working. Even when the engine is running with the run crane relay being held closed manually, I can pull the fuel pump relay out and the engine keeps running.

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Friday, August 19th, 2022 AT 1:57 PM

KEN L

MASTER CERTIFIED MECHANIC
54,144 POSTS

Will your scanner do a CAN scan and if so are there any codes? I see the fuel pump module in the engine wiring diagrams but not the fuel pump relay though I see the relay in the fuse panel. Here are the engine and PCM wiring diagrams so you can see how the system works. What is the manufacturing date of the truck? I don't see the crank/run, start relay either?

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Saturday, August 20th, 2022 AT 4:49 PM

MINNERMP

MEMBER
6 POSTS

I have hooked up to scanners to it and they don’t have any problem connecting to the can, although I do not know if all the Cannes channels are open and connecting. I don’t know what activates the three relays in the fuse panel under the hood, the fuel pump relay, the run crank relay and the start relay, when I turn the key to start. The date of manufacture 02/2017.

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Wednesday, August 24th, 2022 AT 2:49 PM

MINNERMP

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6 POSTS

You can see in this fuse panel that number one in the upper left-hand corner is the starter relay and number two in the middle of the fuse block is the run crank relay and the relay in upper right corner of the small square one is the fuel pump relay.

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Wednesday, August 24th, 2022 AT 2:52 PM

KEN L

MASTER CERTIFIED MECHANIC
54,144 POSTS

This leaves the BCM not triggering the relay. Here is how you can change out the BCM which you can get programmed by searching Google.

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Thursday, August 25th, 2022 AT 5:05 PM

MINNERMP

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6 POSTS

I was kind of thinking that maybe it fried something in the BCM. I just wanted to make sure before I ask to replace it because it’s probably going to be expensive it has to be programmed.

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Thursday, August 25th, 2022 AT 5:22 PM

MINNERMP