Reduced Engine Power - P2135

Discussion in 'Hybrid General Discussion' started by bbOOmm, May 1, 2019.

  1. bbOOmm

    bbOOmm TYF Newbie

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    2008 Chevy Tahoe Hybrid

    DIC - Reduced Engine Power
    ECM error code P2135 Throttle Position Sensors 1-2 not plausible

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    I have:

    removed and cleaned the throttle body

    replaced the throttle position sensor - AC Delco TPS onto the original throttle body

    replaced the complete throttle body assembly with a new AC Delco throttle body

    replaced the 12V battery with a new AGM battery, cleaned the battery terminals

    replaced the throttle position sensor connector thinking maybe corrosion on the contacts

    removed and cleaned the engine ground strap terminals and bolts

    Pulled fuses for the ECM and others, then attempt to start... to introduce new error codes thinking the codes may be stuck in the memory. New codes erase, but the TPS error remains.

    Disconnected the hybrid battery and the 12v battery and let sit overnight - error remains

    I have noticed .... if the weather is over 50 degrees F and dry, seldom does the system go into Reduced engine power. If its cold and /or damp, almost always the ecm goes to reduced engine power.

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    I probably have driven this vehicle 20 miles since November because it is too cold or damp for it to operate. $15K for a driveway brick... I need to find a solution fast before I just say fook it and it goes to the scrap heap and I eat the $ loss.... I'm at wits end with it.

    I'm kind of thinking its the ECM, but also thinking its something else since it -seems- to be moisture sensitive. The ECM is a sealed box.

    I purchased a new ECM ( new, never used ) but I'm confused with what I'm reading online. Some say it needs to be programmed with the VIN and what not. Some say to do some 11 minute on, 30 seconds off procedure - no programmer needed etc ....

    I need a definitive answer on how to replace the ECM. If it needs to be programmed, If I install the ECM, will it be drivable to the dealer to have them program it, or can I take the ECM to the dealer and they can program it outside of the vehicle, or do I need to have the dealer install it AND program it.

    Also, any sugestions on what else it could be would be helpful.

    Thanks
     
  2. BG1988

    BG1988 Full Access Member

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    replacement of random parts is point less

    looks like its an issue with the gas pedal and is worn out. since it has two sensors. and the voltage is not matching.. correctly A/B

    as one voltage rises the voltage on the other drops.. vice-versa. Reduced power mode is just. Safe Mode. so you dont have engine run away or un-intended acceleration


    or. bad wires/ shorted / poor connection
     
    Last edited: May 1, 2019
  3. dnt1010

    dnt1010 Full Access Member

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    If I were "part swapping" I would probably just pop a new throttle position sensor on the accelerator pedal and cross my fingers. Looks like a stock part at Autozone (must be a common failure?) for around 120 bones.
     
  4. John Bragg

    John Bragg Member

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    I have been struggling with this issue myself for over 2 years, however mine is great in cold weather but acts like a bastard in the warmer to hot weather. I have replaced the throttle sensor at the pedal the throttle body assembly mass air flow sensor even the fuel pump and put all new fuel lines in it. And after all that the issue remains so last night as a final ditch effort I put a new ECM in it. After about 10 minutes of driving it kicked on only now instead of just reduced engine power like before it says reduced engine power and idles at 1500 rpm, that's new but still the same old bullshit. I'm over the whole thing can't stand it anymore the only option I see left is a dealer and I'm sure the bill for that repair will be more than the thing is worth. GMC I am very disappointed.
     
  5. bbOOmm

    bbOOmm TYF Newbie

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    The TPS that is on the throttle body is a dual potentiometer (dual variable resistor)... that is where they get the sensor #1 and sensor #2 ... not the Throttle Position Sensor and Accelerator Pedal Sensor being #1 and #2. Its an educated guess since I have not taken one apart ... yet.... but the TPS connector is a 6 pin ... a variable resistor has 3 conductors, a dual variable resistor would have 6 conductors if truly isolated. If the Accelerator Pedal Sensor was bad, there would be a specific code for the APS as well as no control over the engine RPM via the pedal.

    It's not that I'm replacing parts at random.... it's just that something somewhere is having a thermal issue. When its cold, materials contract, in this case it must be breaking the connection. When it's warm, the materials are in contact and it runs like it should. Looking at the wiring schematic... the only thing in line with the TPS wiring is the ECM... nothing else. It's the TPS, the TPS connector, the wires, the ECM connector, and then the ECM itself. The TPS circuits don't even go through the fusebox.

    Years back, I had an old 88 Chevy pickup that would randomly go into limp home mode. After a few headaches, the fix for that was replacing the ECM. This Tahoe has has some really weird stuff happening from time to time. gauges that would move around, engine RPM that would increase/decrease randomly, weird shifting. Hence my thoughts on replacing the ECM on the Tahoe.
     
  6. BG1988

    BG1988 Full Access Member

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    Last edited: May 5, 2019
  7. bbOOmm

    bbOOmm TYF Newbie

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    AH HA!!!! I FIXED IT!!!!

    I was going on the theory of a bad connection at a connector. So Starting at the fuse block, I started removing things. I pulled the fuse block assembly, then the relay block, working my way down to the ECM, I pulled the ECM out of the bracket and while finagling with the harness to get enough room so I could pull the connectors off the ECM, I noticed a little rub mark on the harness. It was rubbed down to the wires and it looked like a couple of the wires insulation were wore down to the copper. I peeled the single layer of crispy electrical tape wire loom back and noticed a green wire was in fact rubbed to the copper. I then recalled seeing a green wire at the TPS connector. So with the DMM I verified it was indeed the same wire.

    Coincidence? Hmmmm....

    So I flooded the wire loom area with liquid electrical tape, then over wrapped the loom with 4 layers of 3M 33 electrical tape. Then put it back together watching where the loom naturally fell into place. I then saw where it was rubbing. Just below and to the front of the ECM is a hose with a metal crimp fitting. The wire loom was just barely touching it. Some additional 3/8" wide heavy duty zip ties and bingo, no more rub.

    So far, I have not had any problems. Just waiting for a good downpour to drive it into to verify my fix, but I'm pretty positive that this was the issue.
     
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  8. Doubeleive

    Doubeleive Supporting Member

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    ^ this is why I am always peering under my hood just looking at stuff (from different angles), if I see something rubbing I find away to prevent it, I've probably saved myself a lot of headache of the years doing this
     
  9. bbOOmm

    bbOOmm TYF Newbie

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    I do the same thing. This location though, no way to see anything unless you started removing stuffz.
     
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