2020 Fails to Start One in 40-50 Starts

[BombshellJT]

I have a 2020 Sport S (heavily modified) that fails to start around once every 40-50 times. Press the start button and things come online but the engine will not start. Press the remote start button and it honks twice but does not start. The problem started back in the Fall. We were up on top of Imogene Pass and it didn't start for us. I put a jumper box on the battery but that didn't help. Disconnected the positive terminal for a few minutes, put it back on and it started. That seemed to be our solution for now. When it would do this, we would disconnect positive for 5 minutes and when we put it back on it starts. I did replace the key fob battery, thinking that could be contributing. It was not.

I started thinking maybe the aux battery was going out, so I removed it. Taped up the negative and ran the positive to the main battery. Didn't change a thing. Last Friday the wife was at work and it would not start no matter what. We towed it to a Jeep shop who kept it for almost a week but they simply could not figure out the problem. They did replace main battery and installed a new aux battery.

Only mod under the hood is a snorkel. Other mods include 4.5" Rock Krawler lift, King shocks, all new steering and suspension components basically. Currently sitting on 35" Patagonia M/T's.

I don't think mods are the cause of the issue. The only thing we can think of to do at this point is take it to a dealership and let their computers diagnose it. We do have a Tazer JL installed. The Jeep shop thought maybe the security gateway module could be a problem. My understanding is the Tazer integrates into the SGM. I just pulled the Tazer JL out to see if that changes anything. Haven't had time to test if that fixed the problem. It is starting at the moment.

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[Mr._Bill]

If you still had the original batteries in a 2020 truck, that is the most likely problem. The AGM batteries have about a three year lifespan in the JT. When they start to fail, it can result in odd issues, other than not starting. The Aux battery is intended to keep the computers stable, since low voltage causes odd behavior and rebooting. Unless the Tazer is causing an issue, you should be okay. These trucks have a fairly significant parasitic draw from all the computers and electronics. If they are not regularly driven for at least thirty minutes, it seems to shorten the life expectancy of the batteries.

 

[BombshellJT]

So the shop did replace both batteries and the problem was still there. They are pretty convinced the security gateway module may be bad and that we should take it to a dealership. The truck is a daily driver and gets plenty of use. I'm going to try doing some testing this weekend without the Tazer to see if it still happens. The one thing the shop didn't do was take the Tazer out of the equation.

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