Baffled by P0202, 03, 05, 08 and P2149

Hoser

Active member
Jun 19, 2016
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Farmington, MN
I’ll try to explain this as quickly as possible. Guy brings me a truck for a bunch of maintenance, cluster repair, and a few other things. He tells me that from time to time he feels like it’s gelling up. Come to find out it’s the classic “tractor mode“. Every time it has happened to him he says he pulls over, turns truck off for 5 minutes, starts it back up and it runs great, he doesn’t touch the injector wires, no problems for another few days to weeks. I’ve had the truck here for a while and I have started it and ran it numerous times, and even had it idling for quite a while as I was setting up a new radio that I installed for him. Truck hadn’t moved since then. A couple days later I start it up and it goes into tractor mode immediately. The codes in title all are on. Truck has harness updates on #2 & #7. I ice picked 2 first, cleared codes, started it, tractor mode, 3 & 5 pop back up. I ice pick 2 again, 3, 5, & 8. Clear codes, start it runs fine for 5 or 10 seconds then tractor mode. I re-crimped the connectors for #2 harness, wiggle wires, pull FICM harness, check for continuity, and voltage. I’ve checked for rub through and there isn’t any.

Basically where I’m at now is the truck will randomly go into tractor mode with what seems to be no rhyme or reason. I’ll start it, it runs like crap, off and on again runs ok for a few seconds then tractor. Off and on again and it runs great. When it is running good I can wiggle all the harnesses and it will not trigger the codes. It’s so intermittent that I’m a bit lost. The only other issue is the batteries do seem to be getting weak, but i wouldn’t think that would matter if it goes into limp mode while he’s driving. One last note, when all the codes pop up, I also get glow plug P0672, 74, 76, and P0101 MAF circuit out of range, however, when truck is not in limp mode there are zero codes. Any thoughts?
 

Hoser

Active member
Jun 19, 2016
227
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Farmington, MN
Been at this thing for the last couple hours. I let the batteries run down to where it would barely start and that did not trigger it. Let it run for awhile, ran great. Grabbed a screwdriver to start moving injector harness wires to see if it would initiate it, and as I was walking towards truck it went into limp. Shut it down, wiggled and shook all harnesses, cleared codes, started back up and has ran great ever since. I have wiggled and shook all the injector harnesses, FICM harnesses, harnesses across the top of motor, everything, several times, and it will not go into limp and is just running perfect. It is so random that I have no idea where to look. Will a failing FICM cause issues like this?
 

Hoser

Active member
Jun 19, 2016
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Farmington, MN
I checked the resistance the night I originally posted this and I had .5 - .6 at all injectors as measured at the FICM harness. Is that the reading you are referring to?
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
yes but you may need it to go into tractor mode and then check again. im willing to bet its an intermittent solenoid over an FICM. the FICM just dont go bad on these things. i could be wrong though.
 

Hoser

Active member
Jun 19, 2016
227
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Farmington, MN
Thanks. I feel like it was in tractor mode when I checked them, but i honestly am not 100% sure. I have been trying to initiate it again, and now it has just been running great, nice and smooth, no stumbles, just perfect. I’ve ran it a bit and driven it, but I’m sure it’ll happen as soon as the owner picks the truck up 😂!
 

Yngdmax92

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Sep 26, 2013
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Just went though this. Undo the batteries and ohm pig tails of injectors too the valve covers. Bet you will find one of them is shorting.

Same symptoms. Fire it up, idle great, hell it would go down the road great. Start giving it some throttle and it kicks the engine light and goes to "tractor" mode. Which ficm is shutting down that bank.

Your shorting out a injector some where or the injector nuts came loose!
 

2004LB7

Well-known member
Dec 15, 2010
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Norcal
Just went though this. Undo the batteries and ohm pig tails of injectors too the valve covers. Bet you will find one of them is shorting.

Same symptoms. Fire it up, idle great, hell it would go down the road great. Start giving it some throttle and it kicks the engine light and goes to "tractor" mode. Which ficm is shutting down that bank.

Your shorting out a injector some where or the injector nuts came loose!

No injector nuts on the LLY but if this was an LB7 then definitely a good possibility.
 

Yngdmax92

Active member
Sep 26, 2013
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Should probably read where the post was written in. Lol thanks! Disregard my help.
 

Hoser

Active member
Jun 19, 2016
227
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Farmington, MN
Just wanted to update this thread. I ended up getting this truck back a couple weeks ago, it hadn’t been driven tons since I last saw it, and it was going into tractor mode again all the time with the same codes when it was driven. I ripped the entire engine harness apart and checked every wire, every rub point for wire breakthrough, ran my fingers along every wire, checked and rechecked resistance at the FICM, and I couldn’t find anything. The only thing that peaked my interest was I was getting ever so slightly more resistance at injector #2 when checking from the FICM harness, and it would vary. Long story short the tech that did the updated injector harness did a very sloppy job. When he stuck the wires in the butt connector most of them didn’t go into the barrel and folded back and didn’t get crimped. Then on top of that, he didn’t get the adhesive lined heat shrink tubing hot enough to seal properly. So the wires were pretty corroded and not fully inserted into the butt connector. I cut that connector out, re-stripped the wires, cleaned them up, and did a good crimp job with a quality but connector and sealed it all up. Customer has been driving it quite a bit lately and it hasn’t missed a beat yet. So just a heads up if anybody else is chasing their tail on this issue.
 
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AndreIgle

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Jul 14, 2022
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I am having the same issue with my 2005 LLY with 130k miles. It already had the #2 & #7 injector update but I will check those wires again