2003 6.0 Not Cranking

[MidlandArmory]

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.

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. I currently have it out to get tested. Maybe the solenoid spun its mortal coil.

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. I am pretty sure I have plenty of juice. I am unsure if both batteries need to be hooked up or if there needs to be a certain amperage reading in order to start when the temp is warm outside. All I know is it cranks when it wants to.

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

 

[DaveBen]

I would start looking at the cables and GROUNDS. Make sure they are tight and clean. Battery cables cause us a lot of problems if they are not looked after. I am assuming by no crank that you literally mean NO CRANKING - NOTHING. Do you hear the starter relay click when you turn the key? Try these and let us know. Good luck!

 

[01yellerCobra]

The next time it does it move the gear selector around and see if it helps. Or move it to neutral and try. If it starts up there's a chance your neutral safety switch is bad.

Granted I'm going with thinking you have power and nothing turns over.

 

[BIG JOE]

I would start looking at the cables and GROUNDS. Make sure they are tight and clean. Battery cables cause us a lot of problems if they are not looked after. I am assuming by no crank that you literally mean NO CRANKING - NOTHING. Do you hear the starter relay click when you turn the key? Try these and let us know. Good luck!

The next time it does it move the gear selector around and see if it helps. Or move it to neutral and try. If it starts up there's a chance your neutral safety switch is bad.

Granted I'm going with thinking you have power and nothing turns over.

x3 and Load Test EACH battery.. independent of each other. All these PSD'd (ECM/PCM's) can be Very Sensitive to having strong, clean Voltage and Amp input.

One weak battery can be a Gremlin.

Joe

 

[MidlandArmory]

The next time it does it move the gear selector around and see if it helps. Or move it to neutral and try. If it starts up there's a chance your neutral safety switch is bad.

Granted I'm going with thinking you have power and nothing turns over.

This is the first thing I tried. Negative results. Someone even told me to try adjusting the foot pedals, which didn't do anything. It appears I have good power, the windows will go down, radio comes on, but I know this means nothing since this can be accomplished with one battery. I found this out when I picked the truck up. When I was driving it back to the state, I stopped to take a nap at a rest stop. When I woke up and went to leave, the truck powered up, but wouldn't crank to start. Looking under the hood I could clearly see it was the Aux power cable (the one that runs over the radiator support) that wasn't connected properly. I messed around with it a little bit and got it to fire up. That was one of the first things I fixed on the truck and I used a genuine factory part. It wasn't cheap, but it fixed a very badly hacked together battery cable.

I will keep checking cables, and there is only one I question. I am taking the starter in to get tested today, I will most likely have the batteries load tested as well. Thanks guys, I will let you know how it goes!

 

[MidlandArmory]

Correction. The battery cable I replaced appears to be the main positive cable. It runs from the drivers side battery over to the passenger side battery, and runs down to the starter all as one unit. This was brand new less than 10,000 miles ago and still looks excellent. Both batteries tested good under my load tester. I will be bringing the starter in soon to have it tested.

 

[MidlandArmory]

Latest update. Starter checks out ok. I can hear the starter relay clicking when I try to start it. I can actually now start the truck by unplugging the connection under the hood on the passenger side and jumping on the positive battery terminal. So what does this leave out, the transmission range sensor?