Need Help

Discussion in 'General Chevy & GM Tech Questions' started by tbone4484, Mar 14, 2012.

  1. tbone4484

    tbone4484 New Member

    I have a 2005 Chevy 2500HD with a 6.0L and an auto trans. My check engine light came on and a few days later the engine began running really rough. Ran the codes and got a UO107 and a P300. The engine seems to be running really lean. Any help about what and where to check first would be of great help.
  2. mfleetwood

    mfleetwood Epic Member 5+ Years ROTM Winner 5000 Posts

    Here is the PO300....I'll look for the other code next.....

    Technical Description

    Random/Multiple Cylinder Misfire Detected
    What does that mean?

    Basically this means that the the car's computer has detected that not all of the engine's cylinders are firing properly.
    A P0300 diagnostic code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why.

    Symptoms may include:

    • the engine may be harder to start
    • the engine may stumble / stumble, and/or hesitate
    • other symptoms may also be present

    A code P0300 may mean that one or more of the following has happened:

    • Faulty spark plugs or wires
    • Faulty coil (pack)
    • Faulty oxygen sensor(s)
    • Faulty fuel injector(s)
    • Burned exhaust valve
    • Faulty catalytic converter(s)
    • Stuck/blocked EGR valve / passages
    • Faulty camshaft position sensor
    • Defective computer
    Possible Solutions

    If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
    If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.
    Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

    ---------- Post added at 10:06 AM ---------- Previous post was at 09:44 AM ----------

    Here is the best U0107 info I could find; please note that information came from a Code Forum, so I'd wait to see how others respond or verify the information before acting.


    I've got a trouble code that I sure could use some help on. My friend has an '04 chevy Silverado with a 6.0L vortec 2wd 3/4 ton automatic trans. In the last couple of days this code has come up 4 times. Each time it does he's had the code erased but it soon pops up again. As you saw in the subject line it is a "U0107" "Lost comm. with throttle control module" The engine seems to go into protection mode and he receives the message"Reduced engine power". He wasn't hard on the engine at the time of these occurrances, in fact, he said he thought he was deccelerating when it happened.
    I've checked for any loose connections and/or bad fuses but it all looks good.

    Do you folks have a clue as to what I'm looking at?
    Thanks in advance for your help.
    This is a tough one for the do it your selfer but here is a operation chart

    DTC U0107 sets if the battery voltage is low. If the customer's concern is slow cranking or no crank because battery voltage is low, ignore DTC U0107. Clear any DTCs from memory that may have set from the low battery voltage condition.
    DTC U0107 sets when there is a short to B+ on the TAC module ground circuit. Inspect the fuses for the circuits that are in the TAC module harness-i.e. cruise, brake. An inspection of the fuses may lead you to the circuit that is shorted to the TAC module ground circuit.
    DTC U0107 sets if the TAC module ignition feed circuit is shorted to a B+ supply circuit. The TAC module stays powered-up when the ignition switch is turned OFF. When the ignition switch is turned ON, the TAC module is powered-up before the PCM. DTC U0107 sets because no communication is detected by the TAC module from the PCM. Inspect related circuits for being shorted to a B+ supply circuit.
    Inspect the TAC module power and ground circuits and the TAC module/PCM serial data circuits for intermittent connections.
    Inspect the TAC module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
    When the TAC module detects a problem within the TAC system, more than one TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing an individual condition may correct more than one DTC. Remember this if you review the stored information in Capture Info.
    For an intermittent condition, refer to Intermittent Conditions

    Last edited: Mar 14, 2012
  3. The Heater

    The Heater Rockstar 100 Posts

    That is tough to backyard that kind of general notification.

    If you want to check something yourself, I would start by randomly pulling some spark plugs. But before you do that, go around to all cylinders, and check to see if the plug boot is tight and does not have any decomposition of the boot or wire. Often it is just a wire that is damaged. If you find a fouled plug, smell for gas. Look for oil. Look for burned electrode. Not completely dispositive, but it at least points toward or away from certain possible issues.

    I am not familiar with the EGR on that rig, but that is also something I would take a look at if it is something a non-professional can check. If that malfunctions, the engine absolutely will not run right, but it is a slow, progressive deterioration, usually.
  4. tbone4484

    tbone4484 New Member

    mfleetwood- I talked with the guy helping me with this and he said the information you gave me for the U0107 code sounds like a good starting point. We are going to start there as soon as we can. He also talked to the people at the garage he used to work for and they said they have had some U codes they could not figure out and had to send them to a dealer. So we'll try and test what you listed and go from there. Hopefully one of those works and I won't have to have it shipped to a dealer. Thanks
  5. mfleetwood

    mfleetwood Epic Member 5+ Years ROTM Winner 5000 Posts

    Good luck and keep us posted...that code sounds like a tricky one.
  6. sstoner911

    sstoner911 Epic Member 5+ Years 1000 Posts

    I had a friend that had the UO700 code on his truck. He replaced the MAP sensor was not very expensive part if I remember correctly.

Share This Page

Newest Gallery Photos