19NA232
Service Bulletin Details
Public Details for: 19NA232
This informational bulletin provides tips for showing a way to confirm if its a mechanical engine issue or not.
Models from 2020
2020 CHEVROLET SILVERADO 2500 |
2020 CHEVROLET SILVERADO 3500 |
2020 CHEVROLET SILVERADO 4500HD |
2020 CHEVROLET SILVERADO 5500HD |
2020 CHEVROLET SILVERADO 6500HD |
2020 GMC SIERRA 2500 |
2020 GMC SIERRA 3500 |
Models from 2019
Models from 2018
2018 CHEVROLET SILVERADO 1500 |
2018 CHEVROLET SILVERADO 2500 |
2018 CHEVROLET SILVERADO 3500 |
2018 GMC SIERRA 1500 |
2018 GMC SIERRA 2500 |
2018 GMC SIERRA 3500 |
Models from 2017
2017 CHEVROLET SILVERADO 1500 |
2017 CHEVROLET SILVERADO 2500 |
2017 CHEVROLET SILVERADO 3500 |
2017 GMC SIERRA 1500 |
2017 GMC SIERRA 2500 |
2017 GMC SIERRA 3500 |
Bulletin No.: Service Bulletin Date: 19-NA-232 October, 2019 INFORMATION Subject: Brand: Chevrolet GMC Diagnostic Tip for Misfire, Malfunction Indicator Lamp (MIL) Illuminated - DTCs P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307 and/or P0308 Model: Model Year: VIN: from to Silverado 2017 2018 Silverado 2500/3500 2019 2020 Silverado 4500HD, 5500HD and 6500HD 2019 2019 Sierra 2017 2018 Sierra 2500/3500 2019 2020 from to Engine: Transmission: L5D, L5P Involved Region or Country North America, Israel Condition Some customers may comment on one or more of the following conditions: • MIL illuminated • Misfire Some technicians may find one or more of the following DTCs set in the Engine Control Module (ECM): • P0300 • P0301 • P0302 • P0303 • P0304 • P0305 • P0306 • P0307 • P0308 Some technicians may find additional DTCs set in the ECM: • P0263 • P0266 • P0269 • P0272 • P0275 • P0278 • P0281 • P0284 • P01CB • P01CC • P01CD • P01CE • P01CF • P01D0 Copyright 2019 General Motors LLC. All Rights Reserved. Page 2 October, 2019 • • • • • • • • • • Cause Correction Bulletin No.: 19-NA-232 P01D1 P01D2 P01D3 P01D4 P01D5 P01D6 P01D5 P01D8 P01D9 P01DA This condition may be caused by one or more of the following conditions: • Fuel Injector • Electrical issue • Loss of cylinder compression Note: The purpose of the bulletin is to show you a way to confirm if you have a mechanical engine issue or not. A Relative Compression test can be used to determine if the misfire is caused by an engine compression issue or not. Service Procedure for Running a Compression Test A technician may find that a relative compression test can be used to rule out an engine compression issue. A relative compression test can be performed with different tools and the engine can be cranked over using many different methods. For this communication, use the PicoScope CH-51450 and available CH-51450-LEAD kits or equivalent. Note: Pull the Fuel Pump Control Module fuse so the engine can be cranked without any fuel being delivered to the engine. 1. Remove the B+ fuse to the FPCM, from the Underhood Fuse Block. 2. Connect the PicoScope to the computer using the included USB cable as you would do using GM NVH. 3. Connect test leads to the battery (hook the colored lead to Battery (+) and the black lead to Battery (-)) and to channel A of the PicoScope. 5419685 4. Open the most current version of PicoScope 6 Automotive for GM software that is loaded when GM NVH software is installed. ⇒ If Picoscope 6 Automotive is not on your computer, download the newest version of Pico Scope NVH Software Update V.R.1.11.1_September_2018 or later. Bulletin No.: 19-NA-232 October, 2019 Page 3 5419699 5. With the PioScope hooked up and the software running, a steady line at battery voltage on the graph should be displayed. 5419709 6. Select the Collection Time drop down. Page 4 October, 2019 Bulletin No.: 19-NA-232 5419718 7. Change the collection time from 5ms/div to 200 ms/div. 5419723 8. Crank the engine for two to three seconds. 9. Immediately after cranking the engine, select the Stop capturing button at the bottom of the screen. Bulletin No.: 19-NA-232 October, 2019 Page 5 5419733 10. Save this file to the PC. ⇒ It may be useful to repeat steps 8 thru 10 a few more times to collect additional wave forms. To do this, you will need to hit the Go or Start capturing button prior to cranking the engine. 11. Disconnect the PicoScope. 12. Reinstall the FPCM fuse. 13. If any codes have set as a result of removing the Fuel Pump Control Module fuse, clear them. Setting Up PicoScope 6 Software to View Waveforms 5419752 To examine one of these wave forms, use the Waveform Buffer Index navigation buttons to locate the start of the cranking. Page 6 October, 2019 Bulletin No.: 19-NA-232 5419756 The graphic above depicts a viewable Wave Form Pattern. To view the Wave Form, zoom in to the right side of the graph. 5419761 Change settings. ⇒ Select the drop down next to the blue “A” (for channel A). Bulletin No.: 19-NA-232 October, 2019 Page 7 5419767 The channel options screen should be displayed. ⇒ Select the Lowpass Filtering Active Filtering check box (1kHz to start). ⇒ Change the Axis Scaling Scale value to 26.00. 5419779 Take note, the voltage graph appears to have disappeared, but if you look at the scaling on the left, you will see that the value is a very high negative number. ⇒ Use the axis scaling offset to bring the graph back into view. Page 8 October, 2019 Bulletin No.: 19-NA-232 5419787 The graphic above depicts a viewable Voltage Graph Pattern. 5419810 Use the waveform Buffer button to move to the next window. Bulletin No.: 19-NA-232 October, 2019 Page 9 5419821 The graph above illustrates an engine that will pass a compression test and there is no reason to think that there is anything mechanically wrong with the engine. ⇒ If the graph does not look like the graph above, Refer to Analyzing Relative Compression Graphs section below. Analyzing Relative Compression Graphs 5419916 When examining these graphs, view the downward portion of the waveform. This area of the graph is the engine starter pulling more electricity from the battery during a compression stroke. Page 10 October, 2019 Bulletin No.: 19-NA-232 5419910 Utilizing a horizontal ruler, line up the bottom of the waveform. ⇒ Select the blue box and drag it to the location that's viewable. 5419940 Vertical rulers may be used as well. Bulletin No.: 19-NA-232 October, 2019 Page 11 5419944 Utilize a second ruler. 5419948 Select the Ruler Settings Button to display the Ruler Setting menu options. Page 12 October, 2019 Bulletin No.: 19-NA-232 5419955 Change the rotation partition to 4, to represent the number of cylinders in the engine. 5419966 This should help to identify the top of each compression stroke in two rotations of the engine. It is not an issue if you see a few of these “tips” that do not touch the line. What we are looking for is consistently one of every four points not hitting the line for a four cylinder engine. Bulletin No.: 19-NA-232 October, 2019 Page 13 Sample Waveforms for Reference 5420017 The graphic above depicts an example of an eight-cylinder engine with a cylinder that has no compression in one cylinder. Note that one of the dips is missing and it repeats every eight dips. – This is a clear indication that there is an issue with this engine. 5420027 The graphic above depicts an example of a four-cylinder engine with a bad exhaust cam lobe. Note that consistently there is one cylinder with an extra-long compression stroke. – Examination of this engine showed that cylinder number four had a worn down cam lobe. Page 14 October, 2019 Bulletin No.: 19-NA-232 5420028 This is a four-cylinder engine with a 20 PSI loss in one cylinder 5420034 This is a four-cylinder engine with a 40 PSI loss in one cylinder. Bulletin No.: 19-NA-232 October, 2019 Page 15 5420040 This is a four-cylinder engine with a 60 PSI loss in one cylinder. 5420524 If an engine has low or high compression on one cylinder, it may be useful to add an injector pulse or a Camshaft Position Sensor to help determine which cylinder has an issue. The graphic above shows the signal from the Cam Position Sensor for reference. Background Information By graphing the battery voltage while cranking an engine, we can get a good picture of how the compression in each cylinder compares to the compression in each other cylinders in the engine. When you think about an engine being cranked over by the starter, each time a piston compresses the charge in the cylinder, the drag on the starter increases which in turn, increases the starter draw and decreases the battery voltage until the air in the cylinder is compressed. After this compression stroke and before the next cylinder in the firing order begins its compression stroke, there is a short period of cranking where the voltage increases. This is what gives the us the pattern to examine on a scope as well as the distinctive sound of an engine being cranked. If each cylinder in the engine are of very close compression, the resulting pattern on the scope will be equal all the way across the screen. If one of the cylinders in a four-cylinder engine has low compression compared to the other three, then every four “waves” will look different than the other three. The same can be said of an eight-cylinder engine that has a weak cylinder, the wave pattern will look different on every eighth wave. Page 16 October, 2019 Version 1 Modified Released October 14, 2019 GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information. Bulletin No.: 19-NA-232 WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION