Intermittent not starting?

PRUITT42

MEMBER
2018 CHEVROLET SILVERADO
5.3L
V8
4WD
AUTOMATIC
225,678 MILES

The past month an half ive had this problem of not wanting to start. Put the key in turn to on position lights come on everything goes away a does crank don’t even try to spin over! Has codes of P0700 an P129D that is TCM and fuel pump driver mod. So ive replaced the fuel pump, fuel pump mod a the ignition switch battery is good I put a new alternator on. So idk what to do ive took it to a dealership a they told me everything was fine because it crunk up for him every time! Help me

Thursday, August 21st, 2025 AT 3:56 AM

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
54,137 POSTS

Yep, intermittent problems can be tough to find. If you upload a short video so I can see what's going on it would be better. When you say everything goes out, it sounds like an internal battery short or corroded battery cables. IF the battery is more than 4 years old I would replace it, also please go over this guide

https://www.2carpros.com/articles/everything-goes-dead-when-engine-is-cranked

P0700 - Transmission Control System (MIL Request)
P129D - Fuel Rail Pressure Too High

So when you say you replaced the fuel pump can I ask if it was the high or low pressure pump? I have seen the fuel pump pressure sensor in the fuel rail cause his problem. Here is the sensor location which is at the end of the fuel rail so you can swap it out, once completed clear the codes. Release the fuel pressure slowly before you begin.

The P0700 code can be caused by the battery issue.

Check out the images (below). Let us know how it goes

Image (Click to make bigger)