2018 SLT Intermittent remote start issue

RPOD71 · February 14, 2020

Back again, next winter season, same issue. Completely random no starts via fob. I don’t have app access unless they offer a free trial. I haven’t taken it to the dealer yet, but I will soon.

I only use the remote start in winter and everything was going well, until it didn’t start before leaving for work (11/22/19). Since then, I started an excel spreadsheet with date, time, temperature, method (fob 1x/2x or key), failed ( Yes or No), and info columns. The 1x/2x for the fob is my way of keeping track if I only used I once or hit it again to get another 10 min of warming up. All entries are 1x. Thinking about it now, I should have kept track if it was running or not when I put the key in and left.

I kept track of every start, even with the key. I was hoping to see a pattern or something that I can take to the dealer to help pinpoint the issue. On 12/19, it started fine with the fob. Made a stop at a gas station 15 min later and used the key (log entry 37) to start it. When it was cranking, it just stopped like I let go of the key. This isn’t the first time this has happened either. I noticed it a handful of times since I owned the truck, random times, random seasons. The next failure came at log entry 100 (weird lol) and it was via the fob. Same story, lights flash once.

Since entry 100, I’ve only been keeping track of remote starts. Today, entry 120, 10 degrees, failed with fob, lights flash once. I was pissed off all the way home lol.

I have zero faith with my dealer and when I take it in next, I will go to a different one, hoping a different set of eyes may solve the issue. I know there are wiring diagrams out there, but does anyone have a ladder diagram of the remote system? I’ll trouble shoot it myself (not the dealers way of trying it a few times and say “looks good to me”). A ladder diagram would be beneficial so I can see what permissives need to be met in order for the fob to work. Plus what volts or ohms the items require to tell the truck to start via the fob because all conditions are met. I know hood, doors, low oil, low fuel are some, (all?)

until then, I’ll continue with my log. Since this has started to be an issue and the sometimes random key start hiccups, I’m leaning towards a bad ground. Somewhere.

Edited February 14, 2020 by RPOD71
Typo

durandetto · February 15, 2020

Couldn't find a wiring diagram.

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RPOD71 · February 18, 2020

Thanks, this will give me a good start. I found an 1100 page pdf on GM Upfitter that I browsed briefly. Seems to have everything electrical. Should be a good read when I start nights later this week. I have unlimited paper at my disposal, but I probably need a few toner cartridges to print it all out at work lol.

durandetto · February 18, 2020

Good luck. I have access to identifix and a dealer parts website, if you need anything else just ask.

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RPOD71 · October 10, 2020

I'm crossing my fingers.. took my truck in for a ticking/tinging sound in the drivetrain and brought up the 'ole intermittent starting issue (again).

This time I had it on video failing. Not sure if it helped, but the mechanic wanted to see the video. So long story short, it stayed there overnight and when I picked it up the next day, the diagnosis was a bad (out of spec negative battery cable under load)

It was dropping over 280mv and should be less than 200. Also said my "driving habits" were not helping the battery charge because I only drive about 30 min to work. Battery was slightly undercharged, which they also corrected.

I'm hopeful the negative cable was the culprit. Real head scratcher about my commute not enough to charge the battery though. It's 3/4 highway speeds.

Side note, the ticking sound was the driveshaft

Darsey · January 25, 2021

I had this exact same thing happen to my 2018 GMC Sierra All Terrain. It was a faulty hood latch, causing the truck to go in to theft mode. Replaced hood latch - good to go.

Jared Watts · July 21, 2023

I would like to know if any of you having this same problem ever found the solution?? I just got my 2014 Silverado that has remote start. (fob only as far as I know. If there is an app, I’m not familiar with it yet ). Most of the time the remote start works just fine, but randomly it wont. Today as I was walking to the truck I heard the very fast bump of the starter like someone mentioned above. After that I tried unlocking then lock/start multiple times and it didn’t attempt again. Started the truck and no CEL. Any help is appreciated