Crank No Start , Help ........... HAS BEEN FIXED NOW

2016 Tundra 5.7 4x4 Limted .
I decided to go under my truck and unplug my fuel control module because I was curious to see what happens when you go to start the truck with it unplugged. went to start the truck and it just cranks as I thought it would, then plugged it back in and it cranks and still wont start., I dis connected the battery for 10 min , re connected it and still just cranks
any idea whats going on >???

 

I'd say start at the beginning make sure battery is fully charged, test relay (they're never bad), inspect as much wire as you can, then to the module there is a way to test the fuel pump at the module to confirm it's good then you're back to the module what I bet is the problem

 

Any wiring mods / add-a-fuses installed?

 

thanks for the replies.
the only thing I did was unplug the module then 2 min later plug it back in.
everything was fine prior. will check fuses and relays (doubt anythings wrong there) in the morning.
At this point im leaning towards either the plug harness to the fuel control module isnt in all the way, or the little wire ends arnt as tight as they should be (may need to test / adjust those metal crimp harness ends,)
OR
Do I need to reset the ECM or ECU ????????.

Any instruction on how to reset the ECM / ECU ?

also, I forgot to mention , while cranking it seemed different. Like if i were to let the key go while cranking it wouldnt stop cranking like normal , id have to turn the key back a click to get the cranking to stop, it just felt real different in that regard.
Maybe the Immobilizer security thing is doing what it should and the ECM needs reset >?

 

Make sure all your ign fuses are tight. I have an add-a-fuse for LED headlights piggybacked on mine and had these exact symptoms (continuous cranking and all) when it worked a little loose.

 

I never reset anything when I replaced my module just disconneced the battery
The continuous cranking after key release is normal it confused me to when mine did the same thing

 

That sucks everything was good now it’s not. I’m not a mechanic but if I was in your position what I would do. I would unplug it again. Go to Walmart and get contact cleaner and spray the connections ( both ends) then put some electrical grease on the ends of the plugs and reinstall making sure they are tight together and giv3 it a try. Also check the fuse for the fuel pump if you know where it’s located Good luck. Let us know how you made out

 

Agree ... disco battery, clean, and probe pins for security.

 

When I posted this late last night I forgot to mention, I did try to start the truck with the harness un plugged from the fuel control module to see what would happen because I was also considering using this area to tap into and install a kill switch into one of these wires , obviouslty it didnt start because it was unplugged, but now im wondering if I tripped it into a safe mode or something? Sorry I should have been more clear in the very first post.
Should I try to do the ECM reset process bridging the #4 & #13 in the data port ??? is there any harm in doing this ?

today I got the test light out and tested all fuses and they check out good. dis connected the neg terminal of the battery , then went underneath and unplugged the wire harness from the fuel control module again. I looked at all 5 active metal wire clip ends and nothing seemed out of place, made sure they were clean. then I removed the nut that holds the fuel control module to the frame rail so I could get it in my hands to look at those terminals. They all looked fine as well, cleaned all the plastic so the harness slides freely with each other, and plugged it back in, re connected the battery, went to start it and same thing is happening, crank but no start.
I did not remove any of the wire ends from the harness connector , not anxious to do that yet didnt want to create any other problems


any other suggestions at this time ?
anyone do that ECM reset before?

 

Can you check the relay switch for the fuel pump? Cause when you disconnected the wire harness going to the fuel pump that caused something to go bad. I would check the fuel system ,fuses,relay
When you turn on the engine ,do you hear the fuel pump?how can you check to see if fuel is flowing from the tank up to the engine.

 

Check the plug that you disconnected.

 

Is there some sort of inertia switch in the unit? When I did my airbags I never elec disco'd it to install relocating bracket. No issues.

 

Thx for the replys, I have checked both ends of the plug multiple times now, un plugged and plugged back in multiple times, all seems good in that area. I have attached pics of both ends of that plug along with the wires coming into it, note there is not supposed to be a wire in slot 4.
I will confirm the relay in the engine compartment is good ,
Im thinking I set something into protection mode or something? like the key immobilizer system

 

Been without a truck for a few days now,
Any ideas , things to check , your experience with crank no start would be greatly appreciated.

 

Check for codes. If it’s an immobilizer issue you should have the indicator on the dash with the key in.

 

Tested the fuel pump? I’m still betting on module

 

At this time I have no way to scan for codes and dont know anyone with a scanner.
with the key out , the red dash icon of the car & lock does its normal blinking.
Once key is inserted , the light is gone.
I doubt its the module or fuel pump , since they were working fine , then I unplugged the module went to start the truck as a test (didnt start like I knew it wouldnt,) then I plugged it back in and expected it to start, and it didnt. I still think something is in a protection mode.
will follow up if anything changes.
Thanks for the replies and ideas, keep em coming

 

Have you verified the fuel pump fuse didn’t blow? It’s a 25A under the hood.

 

My problem has been fixed.
It was the pin tension on the connection at the fuel control module harness (female wire harness end) .
The center (ground wire) was too loose.
If youre curious to what im refering to , it can be seen in this video where this guy had the same problem. If you want to get to the video point, its right at 11:40

https://www.youtube.com/watch?v=miNUy43Qy48&t=918s

thanks to all who replied with advise , ideas and suggestions

 

So I’m currently trying to help a buddy of mine with the same problem. If it’s pin tension that’s great and an easy fix. But how would that happen? If no on has messed with it could it still happen?