Hmmm, a u0107
 

Thought I'd mention an interesting little glitch thats occurred a couple times randomly in the last few weeks. As usual, its way to long.

Synopsis
When driving at low TPS and low Kpa, and decelerating to a roll, or at ultra low tip-in...I can occasionally trigger a u0107. Its happened 4 times, with twice being in one trip.

The first time it happened I momentarily lost throttle control, and it tried to stall out but I popped it into neutral and it caught idle. I was able to drive away seemingly normal.

Second time I was backing up into a parking space, engine cut out (and I didn't even realized it triggered the code because I was already in the parking space and forgot to check when I came back to the car).

Third and fourth time were today. Same situation, going from 35-40 down to a slow roll or at like 2% throttle and Died coming to a stoplight. At first it didn't want to crank over. Tried again (and held on it), and she fired up and was able to drive away again but felt like it was in reduced power.

Did the same thing again, but I was able to clear the code from my scangauge while rolling in neutral and restarted her before traffic flow changed (it was pretty badass, not gonna lie). Return trip from my destination was just fine.


This has never happened while at freeway speeds, during heavy throttle, or from sharp turns or hard stops.


Factors/Ideas

U0107 is a communication failure with the TAC, per GM's list. The description includes possible shorts on the B+ for the TAC, unplugged/damaged/mismatched TB&Pedal issues, or low line voltage on those circuits (short, parasitic draw, or battery/charging issue).

I have unplugged all the TAC and pedal connections and checked them for damaged wires/pins, reset the code, and hard reset from the battery cable. Seems to be fine after a reset or clear, and the code doesn't come on all the time or under all situations.

Truck has had this engine setup for 4+ years without the code ever before. We did make some changes to the tune a few weeks back, but nothing was observed or logged during 2-3 hours of tuning under various conditions on-road.


Starting with battery testing and checking for loose cables and grounds on the chassis. Other thoughts? Its a weird one, and there aren't any other symptoms.

Re: Hmmm, a u0107
 

I had this code a few time in the Suburban, ('04 electronics), I checked everything, Never actually found a smoking gun. Then I realized it only gave the dead pedal/U0107 when I started it after sitting a long time (Over 3 weeks), Using a Battery maintainer fixed it for me.

But your issue sounds different, I would start with Grounds, The Factory TAC module ground is G104 at the back of the block, Your aftermarket harness may have it elsewhere?

What is the Charging Voltage?

How old is your Battery?

Re: Hmmm, a u0107
 

I took the Optima blue in to Napa and threw it on the autocharger. Tested out at 13.something volts and ~1000cca which should be just fine. Battery is only a year or so old. Puts out 12.9 on the multimeter while sitting on the floor.

Haven't checked charging voltage yet, need to do that tomorrow. I don't recall having to hookup another ground for my TAC. I'll have to check my old documentation.

You don't happen to have the listing handy of which pin on the TAC goes to ground, do you?

Re: Hmmm, a u0107
 

Pin 15, C1.
http://i296.photobucket.com/albums/m...psxb9wjucr.gif

Re: Hmmm, a u0107
 

my dude :thumbs:

Re: Hmmm, a u0107
 

Followed that ground pin out of the cab, then picked it up on the other side of the firewall. It terminated with some other grounds on the rear of the motor. Its been like that since the original swap, so nothing on that wiring path has changed at all.

From the alt terminal to ground, I'm getting ~13.7 on the multimeter.

I cleaned out the fuel filter as well today (saw a thread talking about a over-amping pump tripping random U and T codes). Wasn't dirty so I'm counting that off.

Drove it ~35 miles roundtrip to a cruise in tonight, mostly highway at 50-75mph. It didn't pop a code or hesitate at all. It did stumble a little just as I pulled into the cruise night, but had no problems upon starting to leave a little later.

I did have a random stall going from 65-0 on a downhill pretty fast. Even with over 1/2 tank, it seemed like she sloshed and starved. I was able to pop into nuetral and restart easily as I coasted to flat ground with no issues (and no code). I'm not assuming its related, but figured I'd mention it anyway.

Seems like my code only pops under 10-15 minutes of low throttle or 35-0-35 neighborhood driving.