Engine kept cranking without turning keyfob!

[Jebb]

I have been having an on-going problem with my 2017 Hemi 1500 that neither the dealership nor I have been able to find/fix that I first posted about here. It goes into "limp mode" for no apparent reason but then drives normally again after shut down and restart.

I did a "hard reset" on the computer by disconnecting the battery for 30 minutes and connecting cables together to drain any charge. Truck ran great for a long time and I thought I finally fixed it.

WRONG!

Yesterday it did it again (went into limp mode) immediately after backing out of a parking spot. I didn't have time to mess with it so I shut it off and tried to re-start (the usual "trick") but it didn't start on the first crank. So I turned the key again and this time it KEPT cranking even after I turned the key back from "start". It kept cranking non-stop for a few seconds and then finally started. It was like the truck was possessed!

Anyone else had THIS happen before? I haven't. VERY strange.

Truck only has 19,000 miles on it. Already replaced acel pedal assembly, checked wiring, battery, connectors, etc, to no avail. Been to dealer numerous times with no diagnosis.

 

[Burla]

Location? Usually humid regions or cold regions suffer this worst then mild climates, could easily be win module, bypass to diagnose. Gunky internals in module can do all of this and not leave a code.

Dodge Ram WIN module cheap fix (won’t start)

Instead of replacing WIN module just bypass the start function of it by using a push button switch wired into the start relay

youtu.be

 

[Ken226]

It kept cranking non-stop for a few seconds and then finally started. It was like the truck was possessed!

Anyone else had THIS happen before? I haven't. VERY strange.

Your truck has a computer controlling the crank duration. When you turn the key fob to the start position, your just telling the BCM that you want to start the truck. The BCM decides whether to crank or not, and if so, how long to crank for.


If the engine has something wrong that results in a no-start condition, it's normal for the BCM to keep cranking for a few seconds until "IT" (the computer) decides that there is a problem, and kills power to the starter. The BCM doesn't really care that you tried to stop cranking.

It's not posessed. Well, actually, it kinda is. But, it's possessed by a computer, and on purpose.








As to your no-start problem and electrical gremlins. This is going to require a skilled diagnostician. You likely have a corroded connector, wires, circuitboard or something similar, somewhere.

Common places to look are the TIPM connectors and grounds.

A scan tool will likely show some "lost communication with *** module" errors. Something is likely, intermittently, taking down the CAN network somewhere.


Do you happen to live in one of those states that salt the roads every winter?

Oh, and have your battery load tested. With a REAL load tester, like the toaster style one from Harbor Freight. (probably should do this first)

 

[Jebb]

Your truck has a computer controlling the crank duration. When you turn the key fob to the start position, your just telling the BCM that you want to start the truck. The BCM decides whether to crank or not, and if so, how long to crank for.


If the engine has something wrong that results in a no-start condition, it's normal for the BCM to keep cranking for a few seconds until "IT" (the computer) decides that there is a problem, and kills power to the starter. The BCM doesn't really care that you tried to stop cranking.

It's not posessed. Well, actually, it kinda is. But, it's possessed by a computer, and on purpose.

View attachment 580362






As to your no-start problem and electrical gremlins. This is going to require a skilled diagnostician. You likely have a corroded connector, wires, circuitboard or something similar, somewhere.

Common places to look are the TIPM connectors and grounds.

A scan tool will likely show some "lost communication with *** module" errors. Something is likely, intermittently, taking down the CAN network somewhere.


Do you happen to live in one of those states that salt the roads every winter?

Oh, and have your battery load tested. With a REAL load tester, like the toaster style one from Harbor Freight. (probably should do this first)

I guess the cranking issue was, as you say, normal and I've learned is called "Tip Start". I have never come across this before because the truck usually starts nearly instantly. But why it did it do this on the SECOND crank and not the first? Seemed like the PCM was all "confused" at the moment.

Anyhow...

Thank you for the tips. No, I do not live where there is salt on the roads but we did have some big rain storms here recently. Could be moisture somewhere, IDK, but it has also done this during dry weather. This random "limp mode" problem seemed to start after my battery went dead and AAA replaced it a couple of years ago (yeah, it's been going on that long). The truck usually starts up fine but still wondering if the battery has something to do with this. The limp mode ALWAYS kicks in when I have my foot off the gas - so maybe the voltage is sometimes dropping at idle/the battery isn't holding it. Will have it tested with a "toaster" as you suggest.

Stored DTC codes are P2122 and U1428 - which typically indicates a bad accel pedal sensor. I replaced it with a new one - didn't fix it.

There are so many things it COULD be (bad harness, corroded connector, defective PCM, bad battery, etc., etc.) like searching for a "needle in a haystack". Been to the dealership multiple times - once for 2 weeks - and they found nothing.