I figure a lot of us may own 250s or 2500s or larger to haul cars around. Well I have a 2004 GMC 2500 HD with a 6.0 and I am getting that dreaded code. What have I done? Replaced the throttle body twice. Replaced the accelerator pedal sensor. Replaced the fly by wire control module. The harness pigtail at the TPS and harness module pigtail. Replaced the ground strap. And upgraded the alternator to the larger amperage. But here is the real kicker. I have noticed that when the lights come or the AC come on, it seems to go into that mode. Any of you ever run into this issue? And any remedies other than the ones I already did?
What is “that dreaded code” exactly? The message can result from a lot of different things. What ground strap did you replace? The battery cable ground on the front of the Passenger cylinder head should be cleaned for sure.
I had a similar issue with my 06 1500 that showed up as a throttle position sensor code and what not. I cleaned up the ground to the firewall and the ground from the transfer case to the frame under the driver side. No more issues.
The dangerous one the drops your truck to idle while you are doing 70mph in the left lane. Happened to me while on on a NY and scared the hell out of me and the kids. Fortunately the drivers in NY were kind enough to let me over to the shoulder. The “reduced engine power” alarm shows up in the information center. It was so intermittent though but the codes showed up as loss communication. (I forgot the code number). i cleaned all the grounds and connections behind the block, under driver side, and the front frame. Then I proceeded to take apart the engine harness and found 5 out of the 8 wires between the TPS and fly by wire control module had been rubbing within the harness. All 5 were showing bare copper and 2 of them are almost completely worn through or are. I was able to yank them apart. I am going to replace those tomorrow and see what happens. Never crossed my mind that the wires would rub like that to bare copper.
I can't count the number of times that in 2000 and newer GM vehicles that I've found broken wires in the middle of a harness that has never been touched. The insulation is fine, no cracks or holes but you pull on the wire and it breaks. I wonder if when the Chinese are making the spool of wire, the copper comes to an end and they just put another roll of copper on the assembly line and continue installing the insulation. When I look at the broken wire, it's always cut straight with no insulation damage. Very difficult to find.
I think they use 22 gauge throughout the truck. The thinnest wire I have ever seen in a vehicle. Even smaller than that cheap speaker wire. And then to top it all off, when the wire is too long in the harness, it was just bent over and squeezed into the harness. Wonder if my truck was assembled the day they had hangovers or if they just started that day. I think I repaired enough wire. It seems to be running, but this is such an intermittent problem that it is tough to say for sure. But my wife does not trust it and probably won’t for a while. It left us stranded at least 5 times for this issue in the past 2 years. Then the next day it runs great and then for the next 6 months are fine as well. What angers me most is that this is taking time away from me playing with my Buick’s.
Not sure why you’re dismissing the importance of the code. Post the code or codes, or what’s the sense?
You are right. The codes are important. This code is U0107. Believe me I googled it several times. My buddy had one of those scanners that had real time parameters and it confirmed the code. It also said “loss communication with TAC” whenever the truck went into reduced engine power mode. The voltages for TPS 1 and TPS 2 varied in voltages, but TPS2 would read 0volts and then 5 volts and then go back to 0volts. Which is why I jumped the gun and replaced the throttle body. Then I located and cleaned 2 grounds behind the block, then replaced the ground strap between the block and firewall. Then searched for any other ground wires and cleaned (3 under the drivers side on the frame and 2 located on the radiator support). This still continued with the same code so I replaced the accelerator position sensor and then the TAC module. And replaced the throttle body again. And then it still continued so then I put feelers out to see if anybody here has run into that problem and see if anybody ever had that problem. It seemed like there have been other people on line who had this problem but did not have solutions. So after I posted this, i decided to dissect the wiring harness and that is where I found the bare wires. There were a lot of wires in the bundles, but I did see these wires travel between the TAC and throttle body. I also saw a bare wire, almost severed, ground within the harness. Which is why I may have seen this happen consistently when the lights came on. It seems to be running now. I thought I was doing it right by replacing parts. Before checking for broken wires first. Which if I provided that information above first, some of you guys would have told me to do so first. But I thank everybody who looked at this post.
