Engine Exhaust System: Diagnosis Chevrolet Silverado 2500 HD

Diagnostic Starting Point - Engine Exhaust

Begin the system diagnosis by reviewing the system Description and Operation. Reviewing the information will help you determine the correct symptom diagnostic procedure when a malfunction exists. It will also help you determine if the condition described by the customer is normal operation. Refer to Symptoms - Engine Exhaust in order to identify the correct procedure for diagnosing the system.

Symptoms - Engine Exhaust

1. Review the Exhaust System Description and Operation in order to familiarize yourself with the system functions. Refer to «Exhaust System Description»(ref-278055-S02429767452008012100000) .
2. All diagnostics on a vehicle should follow a logical process. Strategy Based Diagnostics is a uniform approach for repairing all systems. The diagnostic flow is the place to start when repairs are necessary and may always be used in order to resolve a system problem. For a detailed explanation, refer to «Strategy Based Diagnosis»(ref-278014-S00951553882008012100000) .

Visual/Physical Inspection

1. Inspect for aftermarket or non-OEM devices such as, but not limited too; tailpipe extensions, headers, and exhaust cutouts. This could affect the operation and proper performance of the exhaust system.
2. Verify the exact operating conditions under which the concern exists. Note factors such as engine RPM, engine temperature, engine load, and frequency of concern.
3. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause any symptom.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. Loss of power. Refer to «Restricted Exhaust»(ref-278055-S26906832212008012100000) .
2. Poor acceleration. Refer to «Restricted Exhaust»(ref-278055-S26906832212008012100000) .
3. Poor fuel economy. Refer to «Restricted Exhaust»(ref-278055-S26906832212008012100000) .
4. Exhaust hissing noise. Refer to «Exhaust Leakage»(ref-278055-S06931791622008012100000) .
5. Exhaust popping noise. Refer to «Exhaust Leakage»(ref-278055-S06931791622008012100000) .
6. Exhaust rattle noise. Refer to «Exhaust Noise»(ref-278055-S24625095682008012100000) .
7. Loud exhaust noise. Refer to «Exhaust Noise»(ref-278055-S24625095682008012100000) .
8. Exhaust buzz, groan, hum noise. Refer to «Exhaust Noise»(ref-278055-S24625095682008012100000) .

Diagnostic Aids

If the vehicle is equipped with a 6.6 L diesel engine do not perform this diagnostic. The exhaust system does not have a location for installing the J 35314-A Exhaust Back Pressure Gage. See Special Tools . Instead remove the suspect component, operate the vehicle, verify for improved performance. If performance is improved then replace the faulty component.

Conditions for Running

The following conditions must be met in order to enable DPF Service Regeneration

1. There are no active DTCs displayed.
2. The battery voltage is greater than 10 volts.
3. The engine speed is between 600-1,250 RPM.
4. The exhaust gas temperature (EGT) sensors 1 and 2 are less than 400°C (752°F).
5. The engine coolant temperature (ECT) sensor 1 is between 70-115°C (158-239°F).
6. The brake pedal and accelerator pedal are in the released position.
7. The transmission is in Park or Neutral.

Test Procedure

1. Clear all DTCs with a scan tool before proceeding with DPF Service Regeneration.
2. Observe the scan tool DPF Regenerations Completed parameter and record the value.
3. Check the following fluid levels before and after this procedure: Engine oil Engine coolant Power steering Transmission Fuel level should be over 15 percent to ensure a successful regeneration.
4. Park the vehicle outside the facility, away from any obstacles, place the transmission in Park and apply the parking brake.
5. Ensure the hood is open.
6. Select DPF Service Regeneration in the Output Controls menu and follow the instruction on the scan tool.
7. Command the DPF Service Regeneration with the scan tool.
8. The DPF Service Regeneration will take approximately 35 minutes consisting of the following: 8 minutes for the exhaust system to warm up, with the engine speed slowly increasing to 1,600 RPM, then 2,200 RPM and finally 2,500 RPM 20 minutes for the DPF to regenerate at 2,500 RPM 3 minutes for the exhaust system to cool down with the engine speed will slowly returning to 1,400 RPM 3 minutes at 800 RPM, then idle speed of 680 RPM
9. The DPF Service Regeneration will be terminated if any of the following actions are performed: Applying the brake pedal Applying the accelerator pedal Selecting Drive or Reverse Commanding DPF Service Regeneration OFF using the scan tool or disconnecting the scan tool from the vehicle
10. After the service regeneration completes, allow the vehicle to idle for an additional 2 minutes while monitoring the scan tool DTC information. There should be no additional DTCs setting. If DTC P224B sets, replace the Exhaust Particulate Filter. If service regeneration aborted or failed, repair the vehicle for the condition indicated by the scan tool DPF Regen Inhibit Reason parameter. Refer to the «Service Regeneration Fault Table»(ref-278055-S08271303142008012100000) .
11. Ignition OFF for 90 seconds, perform the following within 10 minutes of a completed service regeneration. Operate the vehicle within the following conditions to run the DTC. Refer to «DTC P2002»(ref-278077-S33599071502008012100000) . If DTC P2002 sets, replace the Exhaust Particulate Filter.
12. Verify that the scan tool DPF Soot Mass parameter is less than 10 grams. If greater than the specified range, refer to «Service Regeneration Unsuccessful»(ref-278055-S16880496552008012100000) .
13. Verify that the scan tool DPF Regenerations Completed parameter has increased by one. If the value has not increased by one, refer to «Service Regeneration Unsuccessful»(ref-278055-S16880496552008012100000) .