I have a 2003 6.0 Auto that has an intermittent non cranking issue. Once it does crank it fires right up. Usually when it doesn't crank, I just keep trying the ignition until finally something connects and it will begin to crank and then start. Sometimes I can try it twice, other times I may sit there for 5 minutes fighting with it. My only issue is, I need to get this problem fixed before it becomes a bigger issue.

I don't think it is the ignition itself. When I am attempting to crank I can see the window switch lights and other things going off when I crank it which I though was normal when the starter is operating.

My first thought is the transmission range sensor which I am trying to locate. I looked on the transmission itself which seemed to make sense but I wasn't seeing anything familiar. Someone hinted it might be under the dash above the brake pedal but I am not seeing anything jumping out at me.

I also question the starter itself, but I hear no noise coming from it at all when the problem shows itself. No clunk or anything. Which makes me think something is causing the circuit to not function properly.

The other thought I had is a possibility in the wiring somewhere. Maybe a bad ground on one of the batteries? I have a brand new factory positive aux cable so I think I can scratch that off the list. The batteries are also charged as well, but cannot rule out the possibility that maybe one is bad since I did not install them. But I can make sure they are both charged, and the issue remains.

Any thoughts on where I should check? Thanks a bunch!

 

Another thing. I do appear to have full power. Everything works as it should as far as that. I am sure it doesn't mean that one of my batteries are not properly connected.

I currently have the starter out and am going to have it tested. It doesn't seem to be seized up in any way, but maybe the solenoid is toast.

 

Dies the shifter seem sloppy? Next time it happens, try holding the shift lever up and/or try it in neutral. If that consistently solves the problem, it's more than likely the two screws that hold the shift cable bracket to the shift tube under the dash have loosened up. It's a pretty common problem and easy to fix if that's what it turns out to be.

 

This is one of the first things I tried and it didn't seem to do anything. I currently have the starter out to have tested and may as well check the batteries as well.

There really is no rhyme or reason to when the problem will show itself.

 

It could be pitted contactor plate/posts on the starter solenoid. Post on whether the starter test reveals anything . . .

 

I would check the starter relay. Not the large one with the battery cables bolted to it, the one that is inside the under hood fuse box. Look at your owner's manual to locate it. You can swap the starter relay with another relay such as the horn relay, they will be the same just to do a quick and simple test.

 

They ran the starter test 3 times and passed with flying colors. The connections on the solenoid look good. The cable that connects the two batteries and runs down to the starter was replaced with a new factory one less then 10k ago. Batteries both passed the load test. I will look into the starter relay when I get the starter back in.

 

Starter is in, swapped relays and no change. Put the original relay back in place and I can actually hear the relay clicking when I try to start it. What I think it is narrowed down to now is the neutral safety switch or range sensor. The only issue is I have no idea where it is. I don't seem to have the usual one that is found mounted on the transmission. Is it under the dash?

 

Doing a little digging it seems the transmission range sensor is inside the transmission on the 5R110W. From the information I've seen one of the symptoms could be the reverse lights not coming on when put in reverse. I thought I experienced this I while ago and didn't think much of it. Now after jumping the truck to start it using the wire under the hood on the passenger side, I let it run for a little while. After warming up and letting some fluid circulate I shut the truck off and it started with the key as normal. So I am thinking the range sensor is the culprit. Whenever I decide to maybe do a fluid change I will look at changing it out.

 

In the starter relay socket, check for ground to the position that matches blade #85 on the relay, with the key in the run position. If you have ground there, the PCM recognizes that the transmission is in park or neutral.

 

Maybe this will help: