Starting Problem

[MCanning]

I have been having a starting problem. Sometimes after driving a distance, I shut the truck off and awhile later go to start it and I get nothing. The headlights and everything else works but no starter action. I have checked wires and fuses and tried unplugging connectors, and then all of a sudden the truck starts up. I also had a problem today after towing my fifth wheel trailer about 100 miles. The truck started fine after stopping for a short time, but when I pulled back on the road the trans would not upshift correctly and the exhaust brake was not working. After stopping for a short time again, when I started to drive again and the check engine light came on and the trans would not shift higher than 3rd gear. When I got home I checked the codes and they were all three transmission related. I unloaded my trailer and un- hooked the truck, cleared the codes and the truck worked fine, no shifting problems. I had a similar issue last summer after stopping for gas and then heading onto the highway and the truck took a long time upshifting into high gear and the exh. brake not working. Any help would be greatly appreciated. Thanks, Mark

 

[LNaugle]

OK... . what year is the truck? How many miles? Are the batts new? original? Help us help you.

 

[MCanning]

The truck is a 2007 with a 6. 7 and 6 speed automatic. It has 94,000 miles, the batteries were replaced last December. The voltage at batteries reads 12. 85 volts. This started right after having work done at dealer, 02 sensors, fuel system cleaning, and manual regen, also heat shield installed on upstream o2 sensor. The main problem started with the truck not wanting to turn over after driving and then parking for a short time. Lights and everything else worked but no starter operation and indicator for gear would move between park and reverse when I would turn the key. Someone suggested the harness connectors at the fuse box in eng. compartment. There is a very sophisticated latch on conn. and I can't see how to remove it to check the loom connections. Same conn. at trans. All help would be appreciated. Thanks

 

[LNaugle]

I have seen the ignition switches in these trucks do weird things... . Is the starter solenoid clicking or you are getting no response at all?

 

[cerberusiam]

indicator for gear would move between park and reverse when I would turn the key.

That sounds like a sensor problem or misadjusted linkage somewhere. Definitely would cause a no start if it thought it was in gear.

 

[LNaugle]

So have you tried starting it in neutral when this happens?

 

[MCanning]

Initially all I heard was some faint clicking noise coming from near the intake side of the eng. which I assume would be the computer. I did not hear any noise coming from starter. I had the truck at the dealer for some o2 sensor issues several days before this and never had any starting issues prior to that. They replaced both o2 sensors, cleaned the injectors and did a man. regen. I am pretty sure I got some bad diesel after stopping with my fifth wheel. I have made sure the cables and as many connections that I can find are tight and clean.

 

[MCanning]

Yes I moved the shifter through all the gears and then tried it in both park and neutral. I have not tried to see if it will start in neutral when everything is working properly. I just usually start it in park. I did not see any problems when looking on the fuse box where the wires came in but I tried to push on the wire looms just for drill. Yesterday after checking the fuse wiring and towing a trailer about 70 miles I started and shut off the truck three times moving the truck around at a business and then on the fourth time of having to start it , it would not start, but this time I could hear it trying to engage the starter several times like a weak battery and then it started up just fine. How about the key, isn't there a chip in the key that talks to the computer?

 

[MCanning]

I have tried moving the gear selector out of park and down through the range and back and it made no difference, but at first the indicator would move back and forth when turning key. I thought maybe it sounded like a neutral safety switch but I am not sure where the neutral safety switch is located on the trans.

 

[Bob4x4]

The 12. 8 volts at the battery concerns me a fully charged Batt is about 12. 6 at rest... ... When the dealer had it did they rewire the 02 sensor connectors or did they replace the trans harness? If a problem truly starts after work has been done-go back and recheck that first

 

[MCanning]

I checked the batteries after shutting eng. off and without disconnecting cables, and that was the reading I got. The dealer only replaced the sensors and installed a sheet metal shroud around the exhaust pipe which the sensor went through and then put a small blanket around the sensor. There was no wiring replaced. I did not have any starting problems before that, but that could just be a coincidence.

 

[Bob4x4]

The voltage you saw is not really accurate you are seeng a surface charge

 

[MCanning]

I checked the voltage this morning after the truck has sat for a couple of days and it was 12. 57 volts. I drove the truck back and forth to town, about 15 miles each way and started the truck several times while I was out and several more times when I got home and no issues. Besides blowing out the underside of the fuse box with air and checking some more connections, the only change I have made is switching keys to the original spare that I have had since the truck was new. This kind of starting issue is very hard to predict and to duplicate.

 

[Bob4x4]

If it starts with one key and not with the other you have found your problem

 

[MCanning]

The truck would start with the other key but for some reason after driving for some time and then stopping for awhile it would not want to turn over. It was not all the time and was hard to predict. I will keep using the spare key and see if anything changes. I would still like to check the connections on the wire harnesses at the fuse box but cannot see how to release the lever that locks them in place. Any ideas?