Fuel Specific Gravity Testing
Use a J 38641-B Diesel Fuel Quality Tester to measure the fuel specific gravity (API Rating). Follow the instructions on the tool to obtain the proper temperture-adjusted value. This information must be accurate for the proper diagnosis of the fuel system.
Action Taken When the DTC Sets - Type A
The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
Action Taken When the DTC Sets - Type B
The control module illuminates the MIL on the second consecutive ignition cycle that the diagnostic runs and fails.
Conditions for Clearing the MIL/DTC - Type A or Type B
- The control module turns OFF the MIL after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC Last Test Failed clears when the diagnostic runs and passes.
- Use a scan tool in order to clear the MIL and the DTC.
Action Taken When the DTC Sets - Type C
- The control module stores the DTC information into memory when the diagnostic runs and fails.
- The MIL will not illuminate.
- The driver information center, if equipped, may display a message.
Conditions for Clearing the DTC - Type C
- A last test failed, or current DTC, clears when the diagnostic runs and passes.
- Use a scan tool in order to clear the DTC.
Conditions for Clearing the DTC - Type X
This DTC is available in the PCM software, but has been disabled, or turned OFF. In this case, the diagnostic does not run, no DTCs are stored, and the MIL does not illuminate. Type X DTCs are used primarily for export vehicles that do not require MIL illumination or DTC storing.
Diagnostic Trouble Code (DTC) Type(s)
| DTC Code | Federal | California |
|---|---|---|
| P0016 | C | B |
| P0045 | B | B |
| P0046 | B | B |
| P0087 | A | A |
| P0088 | A | A |
| P0089 | C | A |
| P0090 | A | A |
| P0101 | C | B |
| P0102 | B | B |
| P0103 | B | B |
| P0112 | B | B |
| P0113 | B | B |
| P0116 | X | B |
| P0117 | B | B |
| P0118 | B | B |
| P0128 | X | B |
| P0168 | C | C |
| P0181 | B | B |
| P0182 | A | A |
| P0183 | A | A |
| P0192 | A | A |
| P0193 | A | A |
| P0201-P0208 | A | A |
| P0234 | A | A |
| P0237 | A | A |
| P0238 | A | A |
| P0299 | A | A |
| P0300 | C | B |
| P0301-P0308 | C | B |
| P0335 | A | A |
| P0336 | B | B |
| P0340 | A | A |
| P0341 | B | B |
| P0370 | A | A |
| P0374 | A | A |
| P0381 | C | B |
| P0401 | C | B |
| P0403 | C | B |
| P0404 | C | B |
| P0405 | C | B |
| P0406 | C | B |
| P0461 | C | C |
| P0462 | C | C |
| P0463 | C | C |
| P0500 | B | B |
| P0506 | X | B |
| P0507 | X | B |
| P0522 | C | C |
| P0523 | C | C |
| P0530 | C | C |
| P0562 | C | C |
| P0563 | C | C |
| P0567 | C | C |
| P0568 | C | C |
| P0571 | C | C |
| P0601 | A | A |
| P0602 | A | A |
| P0603 | C | C |
| P0604 | A | A |
| P0611 | B | B |
| P0612 | B | B |
| P0621 | C | C |
| P0622 | C | C |
| P0642 | A | A |
| P0643 | A | A |
| P0650 | A | A |
| P0652 | A | A |
| P0653 | A | A |
| P0670 | C | C |
| P0671-P0678 | C | C |
| P0698 | A | A |
| P0699 | A | A |
| P0700 (no mil) | A | A |
| P0802 | B | B |
| P0833 | C | C |
| P1093 | C | A |
| P1094 | C | C |
| P1125 | C | C |
| P1223 | C | B |
| P1226 | C | B |
| P1229 | C | B |
| P1232 | C | B |
| P1235 | C | B |
| P1238 | C | B |
| P1241 | C | B |
| P1244 | C | B |
| P1293 | A | A |
| P1294 | A | A |
| P1295 | A | A |
| P1296 | A | A |
| P1404 | C | B |
| P1550 | C | C |
| P1621 | C | C |
| P1626 | C | C |
| P1631 | C | C |
| P1637 | C | C |
| P1658 | A | A |
| P1687 | A | A |
| P2066 | C | C |
| P2067 | C | C |
| P2068 | C | C |
| P2122 | C | C |
| P2123 | C | C |
| P2128 | C | C |
| P2132 | C | C |
| P2133 | C | C |
| P2138 | C | C |
| P2139 | C | C |
| P2140 | C | C |
| P2146 | A | A |
| P2149 | A | A |
| P2227 | C | B |
| P2228 | B | B |
| P2229 | B | B |
| P2563 | B | B |
| P2564 | B | B |
| P2565 | B | B |
| P2610 | C | C |
| P2636 | C | C |
| U0073 | C | B |
| U0101 | C | B |
| U0105 | C | B |
| U0106 | C | B |
| U1300 | C | C |
| U1301 | C | C |
Diagnostic Trouble Code (DTC) Type(s)
Scheme 327
| Callout | Component Name |
|---|---|
| 1 | Fuel Rail |
| 2 | Fuel Pressure Sensor |
| 3 | Fuel Injectors |
| 4 | Fuel Return Junction Block |
| 5 | Fuel Tank |
| 6 | Fuel Injection Control Module |
| 7 | Fuel Filter |
| 8 | First Start Fuel Bleeder Valve |
| 9 | Fuel Injection Pump |
Fuel Injector Cleaning and Inspection
| IMPORTANT | If reusing the old injectors perform the following |
Scheme 328
- Use a soft bristle non-metallic brush and top engine cleaner, GM P/N 1052626 or equivalent, to remove any deposits from the nozzle tip (1) and the copper washer sealing area (2) before re-installation.
- Inspect the fuel injector nozzle tip (1) for any signs of discoloration (dark yellow, tan or blue) due to excessive heat.
- Replace the injector if any damage is found.
- Clean the fuel injector high pressure line.
- Inspect the fuel injector line for excessive corrosion or damage to the sealing surfaces (1, 2). Replace the line if any damage is found.
| IMPORTANT | If reusing the old injectors perform the following |
- Use a soft bristle non-metallic brush and top engine cleaner, GM P/N 1052626 or equivalent, to remove any deposits from the nozzle tip (1) and the copper washer sealing area (2) before re-installation.
- Inspect the fuel injector nozzle tip (1) for any signs of discoloration (dark yellow, tan or blue) due to excessive heat.
- Replace the injector if any damage is found.
- Clean the fuel injector high pressure line.
- Inspect the fuel injector line for excessive corrosion or damage to the sealing surfaces (1, 2). Replace the line if any damage is found.
Circuit Description
The turbocharger learn procedure is performed automatically during each ignition cycle by the engine control module (ECM). Certain enable criteria must be met for the ECM to perform this procedure. After each ignition cycle, and before the enable criteria for the learn procedure have been met, the ECM will use the previously learned value. If the ECM does not have a previously learn value it will default to a stored calibrated value. The ECM will use this value until the enable criteria have been met, and then it will perform the procedure to learn the new value. If the ECM attempt to perform the procedure and fails, diagnostic trouble codes (DTCs) P0046 or P2563 may set.
The turbocharger learn procedure is required when the following service procedures have been performed
- The turbocharger vane position control solenoid valve replacement
- The turbocharger vane position sensor replacement
- The engine control module (ECM) replacement
- The turbocharger replacement
- Any service that disturbs the turbocharger components
| IMPORTANT | Once the enable conditions have been met the throttle must remain at idle. Do not change the accelerator pedal position (APP) during this procedure. |
- The following conditions must be met for the ECM to perform the turbocharger learn procedure. The A/C is OFF. The vehicle is in Park or Neutral. Start and idle the engine. The engine coolant temperature (ECT) is more than 72°C (162°F).
- After the enable conditions have been met for at least 60 seconds, turn OFF the ignition for at least 30 seconds. The system should have learned the new turbocharger position.
Diagnostic System Check - Engine Controls
The Diagnostic System Check - Engine Controls is an organized approach to identify a problem caused by an electronic engine control system malfunction. This diagnostic check must be the starting point for any driveability complaint diagnosis. The diagnostic directs the technician to the next logical step in diagnosing the complaint.
Use the Engine Scan Tool Data Definitions list for a comparison after fulfilling the following items
- Complete the Diagnostic System Check - Engine Controls.
- Confirm that the on-board diagnostics are functioning properly.
- Confirm there are no diagnostic trouble codes.
The Engine Scan Tool Definitions are an average of display values recorded from normal operating vehicles. The definitions intend to represent what a normal functioning system should display.
| IMPORTANT | Do not use a scan tool that displays faulty data. Report the problem to the manufacturer. Using a malfunctioning scan tool can result in misdiagnosis and unnecessary parts replacement. Use only the parameters listed in the Engine Scan Tool Data Definitions for diagnosis. When a scan tool reads other parameters, General Motors recommends not using the values for use in diagnosis. For more description on the values and the use of the scan tool to diagnose the ECM inputs, refer to the applicable diagnostic file. When all the values are within the range illustrated in the Engine Scan Tool Data Definitions, refer to Symptoms - Engine Controls . |