Extended crank but no start issue

Have you experienced a ECNS

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Flash done today... dealership said it will take 3-4 hours.. FML.. took them 2 to get me in and out. I did notice a bit longer start time, kinda scary the first time as I thought it was going to do the no start again.. but we'll see how it goes going forward.
 
So….. I had the reflash done a while back and just had the extended crank, no start…. Again… tried twice in a row, no go. I unplugged negative battery lead for a minute. Tried again and it fired right up…
 
2021 LM2 Elevation said:
So….. I had the reflash done a while back and just had the extended crank, no start…. Again… tried twice in a row, no go. I unplugged negative battery lead for a minute. Tried again and it fired right up…
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Well that's a drag. Getting close to my bumper to bumper warranty running out. Was thinking about lying and say I had recently had a couple of ecns, to have the update applied. Don't have any issues, so maybe I will leave well enough alone.
 
Im guessing this is a computer thing. When it was trying to start it said low battery in the info screen. It mentioned something about going into battery saver mode. Thats a new one. I unplugged the negative for a minute, reconnected and the truck fired right up. It did ask me to roll the driver side window down and back up… interesting. No problems since. Im guessing there maybe another update coming. I dont think its the exciter wheel postion or whatever. Good thing is disconnecting and reconnecting battery fixes it. I had a 2014 silverado that would say “service stabilitrac” and the steering wheel completely locked up even while moving. Only way to fix was to disconnect battery and reconnect. At first they charged me $600 to replace the battery leads because of low voltage. Turned out they recalled 750k truck because it was a computer issue fixed by an update. Sorry this was long winded.
 
No problems, thanks for the personal experiences.
 
Had it happen for the fourth time last week with almost 17k on my 21. I’m still not sure about getting it reprogrammed. Was a little embarrassing in the Costco parking lot.
 
...so no permanent fix for the ECNS issue? I just had it happen to me again yesterday on my '21 LM2 with ~22k on the clock. Second time in a couple of months and maybe the 5th time since I purchased the truck new. Always starts right back up on 2nd try. Sounds like the reflash does nothing? Still deciding whether or not to hassle with an appointment at the dealer to reflash....Thoughts? Experiences?
 
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I think the reflash helped… for the most part. For my truck, it will not start on the second or third try. I have to disconnect and reconnect the battery for whatever to clear so the truck will start. I have a 10mm socket in the glovebox just in case.
 
I've not had a no crank issue since the software update (whenever that was when I posted in this thread). Sounds like it was the fix for me at least.
 
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I had the issue where it wouldn't start on the 2nd try and had to disconnect/reconnect the battery to get it going. Brought it in a few times and it took the dealer connecting with GM and they had them reprogram the FOBs in a specific way or something as it was something with the FOBs not connecting. Knock on wood it's been working for quite awhile now so hoping they fixed it
 
2020 Silverado LTZ 3.0 Diesel.

Had same problem along with a bunch of other random issues. All under warranty.

9/2/22 DIC “Service Emmisions System”, and “174 miles until 65MPH max speed”. DEF level at about 1/3 full.

9/8/22 intermittent jolts while doing 65-70 mph. Feels similar to running over a bad spot in the road, but road is perfectly smooth. ODB2 P0336 Crankshaft Position Sensor Performance. Replaced sensor.

10/9/22

Throatier noise at idle. Cruise ctrl 55 mph, trans in 6th or 7th, pulling hill w/trailer. Was having problems manually downshifting while in Cruise Control. Engine jolted several times then stopped. DIC reads Service ECS, limit speed to 65mph, limiting power. Pulled to shoulder and engine stopped on its own. Tried to start, but just cranked. Turned everything off, then tried to start and it started.

Noticeable increase in throaty noise at 2000+ rpm.
“Service Emmisions System”, and “174 miles until 65MPH max speed” after some mis-firing events. DEF level at 90% full. Does not go into tow/haul mode.

P0216 Inject timing ctrl circ
P0087 Fuel rail low pressure P020A-F Cyl 1-6 inj timing
P0336 Crankshaft pos sen perf
P034B CS pos sen direct incorrect
P0700 Trans ctrl mod
P228A-B Fuel Pres reg 1-2 ctrl force eng shutdown
U0073 CAN bus communication
U0074 Ctrl mod comm bus B off
U0076 Ctrl mod comm bus D off
U0100 lost comm w/ ECM

10/18/22

Towing 5,700 lb TT. Cruise CTRL at 55. The last 30 miles uphill running in 7th gear 1800 rpm. Instant mpg consistently about 14-15 MPG. I noticed a slight degradation in power for a minute or two while the mpg dropped to 11 or 12. Then several jolts (at least 5) in a row. Each jolt was accompanied by a increase of 300 rpm, then the rpm would drop back to 1800 (like it’s slamming down into 6th gear than shifted back to 7th over about a second). “174 Miles until 65 mph max speed”, “Service Emission System” appears on DIC (DEF showing 3/4 full). This is the same 174 miles as the similar events that occured last week. Check engine light on. Got off at 1st available exit, shut engine off then scanned for OBD2 codes. Only one code P0336 Crankshaft Position Sensor Performance. Code reader had “EGS” and “DPF” flashing red. Started engine back up, Emission warnings cycled then cleared, chk engine still on.

14 mi down road, going downhill, then started back uphill. Cruise control 55, 7th gear, 1800 rpm, mpg about 14. Power degradation, jolts, rpm and mpg changed happen again. Same emissions warnings but 164 mile notice. No new OBD2 codes.

Turned engine back on, cycled “svc emissions “, “164 mi to max 65 mph”, then briefly a 3rd message “3123(?) mi to max 65 mph”.

50 miles later 55mph 7th gear, 1800rpm, pulling hill. Power degradation, jolts, rpm and mpg changed happen again. Emission warning came back up showing 165 miles. Cancelled cruise control and manually dropped to 6th gear (2200 rpm). Jolting cleared up. Tried manually accelerating and jolting started again. Dropped to 5th gear (3000 rpm) jolting cleared up. Pulled off next exit. No new OBD2 codes.

5 miles farther, Many jolts, DIC “power steering assist gone”, “power reduced to 40mph”. Was able to limp off freeway before engine just shut off. Many ODB2 codes (most were the same as last week).

After scanning and documenting all the codes and the events leading up to the shutdown, I was able to restart the engine and drive the last 20 miles home. I didn’t use cruise control, tow haul would not engage, I selected gears so engine was running in the 2500-3000 rpm range.

I took it to the dealer with my 3 page long history. They escalated it to the regional tech guy (old school experience, doesn’t totally rely on computer diagnostics). Determined that the engine wiring harness was the culpret (data network corrupting sensor and module data). I have heard about a bulletin about this.

After wire harness replaced, no more problems.
 
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