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Weird problem that is stumping me p0116, p2155

Odlaw

Redneck
Messages
573
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Location
Deep in the woods - near Waldo, FL
Hey guys, been awhile but honestly, my lbz has been the most reliable truck I've owned. On my way back from a thanksgiving week camping/atv trip to Fat Daddys ATV park outside of Waycross, GA (about 2 hr. 20 min trip), towing my 21 foot enclosed toy hauler at capacity (7k), the passenger side battery took a dump. Noticed a slow start after after filling the tank in Waycross before we headed back. The first thing I noticed was my fuel gauge was way above full, which is not normal, then, several miles down the road she thru a p0116 (engine coolant temperature range/performance problem) and immediately went into (what I think was) limp mode it was skipping and vibrating slightly and it's been so long since she's been in limp mode I don't remember if it studdered like that before. I checked the temps via app and OBD port, everything was normal. Left my tablet on the console and rocked on home, clearing the codes a couple of times. It would seem to only throw the code during the first 10 minutes of driving, once up to temp, no code. And it didn't matter if I was cruising down the interstate or start and stop through small towns. My batteries were almost 5 years old and I've been trying to replace them but interstate has been having trouble getting blems. So, I took the trip knowing that my batteries could be an issue. Called interstate a few days after we got back and they had blems in stock. Installed the new batteries and I have not had that code come up again until yesterday on my way home from work, again before she got up to operating temps. I cleared the code and it came right back, like in 2-3 seconds. At about the halfway point of my 13 mile commute it went in to limp mode again, this time I had a different code, p2155 (fuel injector group D supply voltage circuit/open). It's kidding season on the farm and I have goat kids coming out of my ears so I didn't have time to mess with it last night. This morning, I looked everything over to make sure there were no obvious issues like fuel/air leaks, chaffed wires etc. Embarrassing as it is, back when I had to replace the TCM, I thoroughly cleaned the grounds under the driver door on the frame. Backing up here, I tested the 4wd a week before our trip and it did not work and i had the service 4wd message on the DIC. I worked on that issue for three days before finally checking youtube and only one video of many, the first thing they suggested to test was the grounds, always test the grounds. Well, knowing that I had just thoroughly cleaned the grounds last year, I was like "yeah, whatever, it's not my grounds"...only to decide to just check them. I looked up and I only had one nice, clean, sealed ground...I thought, hmm, I believe there were two grounds under that bolt. Sure nuff, I had flipped one of them over the body mount brace while cleaning them and forgot to pull it back down and connect it while I was troubleshooting my TCM issue. Reconnected that ground and 4wd worked perfectly. I share all of that just to say the grounds are good lol. So, this morning, I did a little more checking including looking for pressed in pins on the connectors to and from the ECM. Started the truck and she purrs like a kitten. I let it idle for about 5 minutes occasionally increasing the rpms. I should also add, I think I need to replace the thermostats again as it does not get to full operating temps when unloaded only when pulling a trailer. They would get to about 185 during the summer empty. I have not road tested it yet and wanted to hop on here to pick the minds of the best in the field!
Thanks guys, Hope you all had a great Christmas and are managing to survive this horrible economy.
Smitty
 
Last edited:

Rockabillyrat

SlIgHtLy StUpId.
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For the p0116 GM issues 2 TSB. One was to update the PCM calibration. The other was a updated block heater cord. Apparently the code would set if you plugged it in when it wasn't cold enough outside. But that doesn't seem like your problem.

I would check your IAT and ECT readings first thing in the morning and compare them to ambient temp. If either one is reading 5* off from the actual temp is can cause that code to set. Ive see IAT sensors set a p0116

For the p2155 9/10 times thats a wiring issue. Ohm each injector at the PCM connector and look for about .2-.3 ohms. I will also check for a short to ground as well. If any are out of spec then that will give you a direction to start looking at. If its out of spec at the PCM connector but not the injector itself then that's a wiring problem. Pay close attention to the big connector on the drivers valve cover. I see alot of issues with thoes.
 

Odlaw

Redneck
Messages
573
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30
Location
Deep in the woods - near Waldo, FL
For the p0116 GM issues 2 TSB. One was to update the PCM calibration. The other was a updated block heater cord. Apparently the code would set if you plugged it in when it wasn't cold enough outside. But that doesn't seem like your problem.

I would check your IAT and ECT readings first thing in the morning and compare them to ambient temp. If either one is reading 5* off from the actual temp is can cause that code to set. Ive see IAT sensors set a p0116

For the p2155 9/10 times thats a wiring issue. Ohm each injector at the PCM connector and look for about .2-.3 ohms. I will also check for a short to ground as well. If any are out of spec then that will give you a direction to start looking at. If its out of spec at the PCM connector but not the injector itself then that's a wiring problem. Pay close attention to the big connector on the drivers valve cover. I see alot of issues with thoes.
Actually, started with the easy one first.
Ambient temps at 8:30 this morning= mirror said 65 digital thermometer sitting on the cowl, leaning against the back edge of the hood= 67.6
IAT=69.8
ECT=68

Will try to test the wiring to the injectors tomorrow. I did drive it yesterday about 40 miles round-trip, no check engine light/issues. Engine temps never got above 176 though...got to order some gm thermostats.
 

Odlaw

Redneck
Messages
573
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Location
Deep in the woods - near Waldo, FL
Strange update; I've driven the truck for a 200+ miles with no issues, with the p0116 code still displaying. This morning, for whatever reason I decided to clear the code after a cold start. About 54% through clearing the code it started missing hard. Scanned again and I had the p2155 code displayed. Cleared that and she smoothed right out. So, this kind of goes along with what it was doing a few weeks ago when I cleared the P0116 code while driving, it did the same thing. I'm going to work on resolving the p0116 code first and see where that takes me. Of course, my d-max is not my daily driver any more thanks to that potato brain sitting in the white house. I had to purchase a little ford ranger gasser because I travel a lot for my job and even though I get reimbursed for travel it was killing me at $5-$6 per gallon. So, not sure how quick I'll get to this but it is on my list of things to do. lol
 

BigDogYJ

Well-Known Member
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Kommifornia
I haven't experienced P2155 my self but did find this which I kept a copy of from years back when I ran into fuel issues. It's related to the injector group 4 (injectors 3 and 8). but I remember something about too high of pressure coming from a lift pump possibly causing this as well as it causes additional load on the circuit controlling the injectors. Might be something to look into.


Circuit/System Description

The engine control module (ECM) supplies voltage to each fuel injector on the injector positive voltage control circuits. The ECM energizes each fuel injector by grounding the control circuit of that fuel injector. The ECM monitors the status of the injector positive voltage control circuits and the fuel injector control circuits. The injectors are separated into the following four groups:


  • Group 1-DTC P2146 with injectors 1 and 4
  • Group 2-DTC P2149 with injectors 6 and 7
  • Group 3-DTC P2152 with injectors 2 and 5
  • Group 4-DTC P2155 with injectors 3 and 8
When a fuel injector circuit condition is detected by the ECM, the fuel injectors in the affected group will be disabled and set the group DTC and may also set the fuel injectors DTCs.

Conditions for Running the DTC



  • The ignition is ON.
  • The charging system voltage is between 6-18 volts.
Conditions for Setting the DTC



  • The ECM injector output driver detects an incorrect current on a fuel injector circuit.
  • The above condition is present for 3 seconds for groups 1, 2, and 3.
  • The above condition is present for 5 seconds for group 4.
Action Taken When the DTC Sets

DTCs P2146, P2149, P2152 and P2155 are Type A DTCs.

Conditions for Clearing the MIL/DTC

DTCs P2146, P2149, P2152 and P2155 are Type A DTCs.

Circuit/System Testing

Important: If you cannot duplicate the condition, operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.



  1. Turn OFF the ignition.
  2. Disconnect the ECM connector.
  3. Connect a test lamp between the fuel injector positive voltage control circuit and battery voltage. The test lamp should not illuminate.

    • If the test lamp illuminates, test the fuel injector positive voltage circuit for a short to ground.

  1. Connect a test lamp between the affected fuel injector positive voltage control circuit and a ground. The test lamp should not illuminate.

    • If the test lamp illuminates, test the fuel injector positive voltage control circuit for a short to voltage.

  1. Connect a test lamp between the affected fuel injector control circuit and battery voltage. The test lamp should not illuminate.

    • If the test lamp illuminates, test both fuel injector control circuits of the affected group for a short to ground.

  1. Test the affected fuel injector positive voltage control circuit and the fuel injector control circuit for high resistance.
  2. Test the affected fuel injector for high resistance.

    • If all circuits test normal, replace the ECM.
Component Testing



  1. Disconnect the connector of the fuel injector to be tested.
  2. Connect a DMM between the terminals of the fuel injector and measure the resistance. The resistance should be 0.2-0.3 ohms.

    • If resistance is more than 0.2-0.3 ohms resistance, replace the fuel injector.
Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


  • Fuel Injector Replacement (Left) Fuel Injector Replacement (Right)
 
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