Filed Under (Chevrolet Manuals) by admin on 31-05-2012
The number below refers to the step number on the diagnostic table. 2. This test determines if the conditions exist in order to set the DTC P0152. 3. If the HO2S (Bank 2, Sensor 1) is intrnally shorted, the HO2S (Bank 2, Sensor 1) voltage displayed on a scan tool will be over 1.0 volt (1000 mV). Important: Before clearing DTCs, use the scan tool in order to record the Freeze Frame and the Failure Records for reference. This data will be lost when the Clear DTC Information function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? — Go to Step 2 Go to Powertrain On Board Diagnostic (OBD) System Check 2 1. Connect the scan tool. 2. Run the engine at the normal operating temperature. 3. Place the vehicle in park or neutral. 4. Apply the parking brake. 5. Increase the engine speed to the specified value. Does the scan tool data display indicate HO2S sensor voltage fixed above the specified value? 1200 RPM 0.976 V (976 mV) Go to Step 3 Go to Step 4 3 1. Disconnect the HO2S. 2. Turn on the ignition while leaving the engine OFF. 3. Turn ON the ignition leaving the engine off. Does the scan tool data display indicate the HO2S voltage near the specified value? 400 mV) Go to Step 6 Go to Step 5 4 The DTC is intermittent. Are any additional DTCs set? — Go to the applicable DTC table Go to Diagnostic Aids 5 1. Check for a short to voltage in the HO2S Signal circuit. 2. If a problem is found, repair the circuit as necessary. Refer to Wiring Repairs in Electrical Diagnosis. Was the HO2S Signal circuit shorted? — Go to Step 8 Go to Step 7 6 Replace the HO2S. Refer to Heated Oxygen Sensor (HO2S) Replacement . Is the action complete? — Go to Step 8 — 7 Replace the VCM. Important: When replacing the VCM, the new VCM will need to be programed. Refer to VCM Replacement/Programming . Is the action complete? — Go to Step 8 — 1. Use the scan tool in order to select the DTC and the Clear DTC Information functions.
Filed Under (Chevrolet Manuals) by admin on 01-06-2011
Conditions for Setting the DTC The voltage on the ignition control circuit exceeds 4.9 volts, and the engine speed is less than 250 RPM. Action Taken When The DTC Sets Conditions for Clearing the MIL/DTC The VCM turns OFF the MIL after 3 consecutive driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (the coolant temperature has risen 22°C (40°F) from the start-up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle) or the scan tool clearing feature has been used. Diagnostic Aids A poor connection, a rubbed through wire in the insulation, or a wire broken inside the insulation will cause an intermittent. Check for the following conditions: Test Description The numbers below refer to the step numbers in the diagnostic table. 2. This determines if the DTC is an intermittent. 3. This check determines if the IC signal from the VCM is available at the ignition coil driver. 4. The remaining tests begin to check that the coil driver circuitry is OK. • The VCM turns the MIL ON when this DTC is reported and one failure has occurred. • The VCM records the operating conditions at the time the Diagnostic Fails. Freeze Frame and Failure Records store this information. • Poor connection • Damaged harness: Inspect the VCM harness connectors for the following conditions: – Backed out terminal C3 pin 9 – Improper mating – Broken locks – Improperly formed or damaged terminals – A poor terminal to wire connection and – Damage to the harness. • Intermittent test – If the connections and the harness check OK, monitor a digital voltmeter connected between VCM connector C3 pin 9 and C4 pin 18 while moving related connectors and wiring harness. If the failure is induced, the voltage reading will change. This may help to isolate the location of the malfunction.
Engine Fan Runs Constantly If you receive customer reports in the above model vehicles of the engine fan running constantly with code P2073(004) Electric fan for engine & AC, open circuit; this may be caused by the wiring harness between the ECU and the engine fan or the engine control unit fan end stage malfunctioning. To resolve, perform the below procedure. Note: Only vehicles as outlined in Service Campaign Bulletin No. 2003110006 are affected, see vehicle range shown. When performing Service Campaign Bulletin No. 2003110006 only, the engine ECU does not need to be exchanged. All engine ECUs exchanged under warranty for the above condition must be accompanied by the freeze frame data for the respective DTC. Claims submitted without this information will be debited back to the dealer Remedy: 1) Check wiring harness between engine ECU connector (pin 39) and engine fan connector (pin 4) for continuity. IF OK, proceed as follows. 2) Replace engine control unit (AR07.08-P-7008P) 3) Install adapter harness a. Remove lower underbody panel b. Disconnect engine wiring harness plug from engine fan C. Connect adapter wiring harness between fan connector and engine wiring harness. d. Secure adapter wiring harness with loom ties (Figure 1). e. Secure adapter wiring harness plug to engine fan (Figure 2)
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