Sudden No Start Issue

[Broosedamoose]

So twice I've turned the key to start the truck and it pause a second before turning over and starting. This morning I turned the key and nothing happened! I held the key in the start position for a few seconds hoping it would start but no luck. The last time something like this happened it would crank but not start and it turned out that the fuse for the 12V feed to the coil was corroded. I recently had an issue with my drivers side door lock/unlock switch not working and when I went to replace it I found a couple of the pins were corroded. I cleaned them and it worked fine. So I am suspecting another corrosion case here but I'm not sure. I disconnected the battery and cleaned the post, though they were not too bad. While it was disconnected I pulled the PCM connector and everything is clean. I tried starting her up again but still nothing. It's not a PATS issue because the light doesn't flash and goes out. where should I check next? Oh, I also checked the PCM fuse and it's good.

 

[2011Supercab]

No clicking or anything?

Underhood fuse box

Check fuses
#7 - 40 amp
#9 - 40 amp

 

[Broosedamoose]

What the heck! I just went out to try it and listen for any "clicks" and she started right up! I did pull #7 and #9 fuses and they are clean and good. Gonna wait for it to warm up a bit outside and then check all the fuses and relays under the hood.

 

[Eddo Rogue]

Might be simply the ignition key switch itself. I've come across a few going bad, especially on fords.

 

[RonD]

Try shifting automatic to Neutral next time it doesn't crank, could just be loose shifter under dash, common Ford Truck issue, so not moving DTR sensor fully into Park

Unplug and plug back in DTR sensor connector on drivers side of trans, cleans the contacts
The 12v that activates the starter relay travels thru that connector

 

[alwaysFlOoReD]

May be loose connection at starter. Or at battery or solenoid

 

[Broosedamoose]

Might be simply the ignition key switch itself. I've come across a few going bad, especially on fords.

Not the ignition switch because it's doing the same thing using the Remote Start.

Try shifting automatic to Neutral next time it doesn't crank, could just be loose shifter under dash, common Ford Truck issue, so not moving DTR sensor fully into Park

Unplug and plug back in DTR sensor connector on drivers side of trans, cleans the contacts
The 12v that activates the starter relay travels thru that connector

Tried putting it in Neutral but same results. I pulled the DTR Sensor connector and inspected the contacts and they look pretty clean but I connected/unconnected a few times. She started the first two times but failed on the third! It was only 21 degrees outside so I couldn't spend a lot of time checking other things. I had the same exact issue last winter and that's when we found the fuse for the12V feed to the coil pack was corroded. When it was cold she would crank but no start. Once the temp rose above around 35 degrees she would fire right up! I hate trouble shooting electrical issues!

 

[RonD]

2007 START circuit is pretty straight forward

When you turn the key to START ignition switch sends 12v to Fuse 21 in Cab fuse box
Fuse 21 passes that 12v to DTR switch on transmission
If DTR is in Park or Neutral it passes the 12v to starter relay in engine fuse box
If PATS is OK then PCM(computer) will have already Grounded the starter relay
So it closes and sends 12v, from fuse 7 in engine bay fuse box, to Starter Motor Solenoid which activates starter motor

I guess if you have a helper they could put a finger on starter relay in engine fuse box and feel if it "clicks" with key turned to START, and there is a no start/no crank

If Starter relay is not activating then either its not grounded by PCM, or its not getting the 12v from fuse 21 in cab fuse box
You could pull the 3 connectors on PCM and reconnect, could be a weak ground or weak connection to starter relay ground

If relay does activate then the 12v from fuse 7 is not being received at starter motor solenoid

 

[Broosedamoose]

Turned out to be the starter relay. Thanks again RonD! I got a helper and followed everything. When we got to the starter solenoid there was no "clicking". Pulled it and found the 12V contact was corroded. Used a little emery cloth and it starts up fine. Haven't had an issue since.