Diagnostic Procedures
WARNING: This page is about a different car, the 2003 GMC Sonoma and 2003 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.
- Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.
- Turn ignition on, with engine off. Does the Secondary Air Injection (AIR) pump run constantly? If yes, go to next step. If no, go to step 4 .
- Turn ignition off. Remove the AIR pump relay. Turn ignition on, with engine off. Does the AIR pump run continuously? If yes, go to step 32 . If no, go to step 5 .
- Command the AIR pump ON and OFF with a scan tool. Does the AIR pump turn ON and OFF? If yes, go to step 15 . If no, go to step 6 .
- Turn ignition off. Probe the AIR pump relay control circuit at the fuse block with a test light connected to battery positive. Does the test light illuminate? If yes, go to step 35 . If no, go to step 56 .
- Turn ignition off. Remove the AIR pump relay. Turn ignition on, with engine off. Probe the AIR pump relay battery positive voltage circuit at the fuse block with a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 29 .
- Probe the ignition 1 voltage circuit of the AIR pump relay with a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 11 .
- Probe the control circuit of the AIR pump relay at the AIR fuse block with a test light connected to battery voltage. Command the AIR pump relay ON and OFF with a scan tool. Does the test light turn ON and OFF when commanded with a scan tool? If yes, go to next step. If no, go to step 26 .
- Connect a fused jumper wire between the battery positive voltage circuit of the air pump relay and the air pump supply voltage circuit of the air pump relay. Does the air pump turn on? If yes, go to step 41 . If no, go to next step.
- Turn ignition off. Disconnect the AIR pump connector. Probe the AIR pump supply voltage circuit with a test light connected to a good ground. Does the test light illuminate? If yes, go to step 12 . If no, go to step 49 .
- Is IGN E fuse open? If yes, go to step 36 . If no, go to step 53 .
- Remove fused jumper wire from the relay block. Connect a jumper wire between each of the terminals in the AIR pump harness connector and the corresponding terminal at the AIR pump. Connect the Connector Test Adapters (J-36169-A) at the AIR fuse block. Measure the voltage from the AIR pump supply circuit of the AIR pump (Black lead) to the AIR pump supply circuit of the AIR pump relay (Red lead) with a DVOM. Is the voltage more than 0.5 volt? If yes, go to step 49 . If no, go to next step.
- Remove Connector Test Adapters (J-36169-A). Remove jumper wire from the ground side of the AIR pump harness connector. Probe the AIR pump ground circuit with a test light connected to battery voltage. Does the test light illuminate? If yes, go to next step. If no, go to step 50 .
- Connect the jumper wire between the ground terminal of the AIR pump harness connector and the corresponding terminal at the AIR pump. Ensure that the AIR pump supply voltage jumper wire is still connected. Connect the Connector Test Adapters (J-36169-A) at the AIR fuse block. Measure the voltage from the AIR pump ground circuit of the AIR pump (Red lead) to a good ground (Black lead) with a DVOM. Is the voltage more than 0.5 volt? If yes, go to step 50 . If no, go to step 43 .
- Start and operate engine at idle until closed-loop operation is achieved. Increase the engine speed to 1500 RPM. Monitor the O2S voltage parameter with a scan tool. Command the AIR pump relay ON with a scan tool. Does the O2S voltage parameter drop to less than 50 mV within 10 seconds? If yes, see DIAGNOSTIC AIDS . If no, go to next step.
- Turn ignition off. Disconnect the AIR shut-off valve vacuum hose. Connect a vacuum pump to the shut-off valve and apply 10 in. Hg (33 kPa) of vacuum to the valve. Does the shut-off valve hold vacuum for one minute? If yes, go to next step. If no, go to step 57 .
- Disconnect the vacuum pump from the AIR shut-off valve. Connect a vacuum gauge to the AIR shut-off valve hose. Start and operate engine at idle. Command the AIR pump relay ON with the scan tool. Does the vacuum increase to more than 14 in. Hg (47 kPa)? If yes, go to step 20 . If no, go to next step.
- Turn ignition off. Disconnect the AIR solenoid connector. Probe the AIR solenoid ground circuit with a test light connected to battery positive. Does the test light illuminate? If yes, go to next step. If no, go to step 50 .
- Turn ignition on, with engine off. Probe the AIR solenoid voltage supply circuit with a test light connected to a good ground. Command the AIR pump relay ON with a scan tool. Does the test light turn ON when commanded with a scan tool? If yes, go to step 22 . If no, go to step 28 .
- Connect the vacuum hose to the AIR shut-off valve. Disconnect the AIR pump crossover hose at the exhaust check valve. Start and operate engine at idle. Command the AIR pump relay ON with a scan tool. Is air pressure present at the AIR crossover hose? If yes, go to step 47 . If no, go to next step.
- Turn engine off. Connect the AIR pump crossover hose at the exhaust check valve. Disconnect the AIR pump crossover hose at the AIR shut-off valve. Start and operate engine at idle. Command the AIR pump relay ON with a scan tool. Is air pressure present at the outlet of the AIR shut-off valve? If yes, go to step 54 . If no, go to step 25 .
- Connect the AIR solenoid connector. Disconnect the vacuum hose to the shut-off valve at the AIR solenoid. Install a vacuum gauge at the AIR vacuum control solenoid port. Start and operate engine at engine. Command the AIR pump relay ON with a scan tool. Does the vacuum increase to 14 in. Hg (47 kPa)? If yes, go to step 45 . If no, go to next step.
- Disconnect the AIR solenoid supply vacuum line from the inlet of the AIR solenoid. Connect a vacuum gauge at the vacuum hose. Start and operate engine at engine. Is the vacuum more than 14 in. Hg (47 kPa)? If yes, go to step 42 . If no, go to next step.
- Remove check valve. Install a vacuum gauge in the engine side of the vacuum hose. Start and operate engine at idle. Is the vacuum more than 14 in. Hg (47 kPa)? If yes, go to step 40 . If no, go to step 48 .
- Disconnect the AIR pump outlet hose at the AIR shut-off valve. Start and operate engine at idle. Command the AIR pump relay ON with a scan tool. Is air pressure present at the outlet hose? If yes, go to step 57 . If no, go to step 27 .
- Test the AIR pump relay control circuit for an open or short to voltage. Did you find and correct the condition? If yes, go to step 61 . If no, go to step 44 .
- Disconnect the AIR pump outlet hose at the AIR pump. Command the AIR pump relay ON with a scan tool. Is air pressure present at the AIR pump outlet? If yes, go to step 37 . If no, go to step 38 .
- Test the AIR solenoid supply voltage circuit for an open, a high resistance or a short to ground. Replace the AIR solenoid fuse as necessary. Did you find and correct the condition? If yes, go to step 62 . If no, go to step 46 .
- Probe both sides of the AIR fuse with a test light connected to a good ground. Does the test light illuminate on both sides of the fuse? If yes, go to step 52 . If no, go to next step.
- Does the test light illuminate at one side of the fuse? If yes, go to next step. If no, go to step 51 .
- Test the battery positive voltage circuit between the AIR and the relay for a short to ground. Replace the AIR fuse as necessary. Did you find and correct the condition? If yes, go to step 62 . If no, go to step 33 .
- Test the AIR pump supply voltage circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 61 . If no, go to step 34 .
- Test the AIR pump supply voltage circuit for a short to ground. Did you find and correct the condition? If yes, go to step 62 . If no, go to next step.
- Install the AIR pump relay. Disconnect the AIR pump harness connector. Replace the AIR fuse as necessary. Turn ignition on, with engine off. Connect a test light between the supply voltage circuit and the ground circuit of the AIR pump harness connector. Command the AIR pump relay ON and OFF with a scan tool. Does the test light turn ON and OFF when commanded ON and OFF with a scan tool? If yes, go to step 58 . If no, go to step 56 .
- Test for a short to ground in the AIR pump relay control circuit. Did you find and correct the condition? If yes, go to step 61 . If no, go to step 60 .
- Test the ignition 1 voltage circuit for a short to ground between the IGN E fuse and the AIR pump relay. Replace the IGN E fuse as necessary. Did you find and correct the condition? If yes, go to step 62 . If no, go to step 39 .
- Inspect for a restriction or a leak in the AIR pump outlet hoses. Did you find and correct the condition? If yes, go to step 62 . If no, go to step 39 .
- Inspect for a restriction or a leak in the AIR pump inlet hoses. Did you find and correct the condition? If yes, go to step 62 . If no, go to step 58 .
- Replace the component that is shorted to ground. After repairs, go to step 62 .
- Inspect the vacuum line between the check valve and the AIR vacuum control solenoid for leaks, restrictions, looseness or splits. Did you find and correct the condition? If yes, go to step 62 . If no, go to step 55 .
- Test for an intermittent and for a poor connection at the AIR pump relay. Did you find and correct the condition? If yes, go to step 62 . If no, go to step 56 .
- Test for an intermittent and for a poor connection at the AIR solenoid. Did you find and correct the condition? If yes, go to step 62 . If no, go to step 59 .
- Test for an intermittent and for a poor connections at the AIR pump. Did you find and correct the condition? If yes, go to step 62 . If no, go to step 58 .
- Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step 62 . If no, go to step 60 .
- Repair vacuum hose between the AIR vacuum control solenoid and the AIR shut-off valve for a restriction, splits or a loose condition. After repairs, go to step 62 .
- Repair short to voltage in the AIR vacuum solenoid supply voltage circuit between the AIR solenoid fuse and the AIR solenoid. Replace the AIR solenoid fuse as necessary. After repairs, go to step 62 .
- Repair restriction or leak in the exhaust check valve, exhaust check valve outlet pipe or exhaust manifold. After repairs, go to step 62 .
- Repair restriction or leak in vacuum hose between the check valve and intake or the vacuum outlet port. After repairs, go to step 62 .
- Repair open or high resistance in the AIR pump supply voltage circuit. After repairs, go to step 62 .
- Repair open or high resistance in the AIR pump ground circuit. After repairs, go to step 62 .
- Repair open or high resistance in the battery positive voltage circuit between the battery fuse and the AIR fuse. After repairs, go to step 62 .
- Repair open circuit in the battery positive circuit between the AIR fuse and the AIR pump relay. After repairs, go to step 62 .
- Repair open or high resistance in the ignition 1 voltage circuit. After repairs, go to step 62 .
- Replace AIR crossover hose. After repairs, go to step 62 .
- Replace vacuum check valve. After replacing check valve, go to step 62 .
- Replace AIR pump relay. After repairs, go to step 62 .
- Replace AIR shut-off valve. After repairs, go to step 62 .
- Replace AIR pump. After repairs, go to step 61 .
- Replace AIR solenoid valve. After repairs, go to step 62 .
- Replace PCM. See appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After replacing PCM, go to next step.
- Ensure the AIR fuse and the solenoid fuse are installed and not open. Ensure all components are installed and secured. Ensure all connections are connected and secured. Turn ignition on, with engine off. Command the AIR pump relay ON and OFF. Does the AIR pump turn ON and OFF when commanded with a scan tool? If yes, go to next step. If no, go to step 2 .
- Clear DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step 2 .
- Using scan tool, observe the stored information and capture information. If scan tool displays any undiagnosed DTCs, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are displayed, system is okay.
NOTE:
Inspect vacuum check valve for proper installation. The tapered side of check valve goes towards the vacuum source.
NOTE:
A short to voltage on this circuit will cause the AIR pump to run constantly with the key in the OFF position. After repairs, ensure to retest the AIR pump operation.
NOTE:
This circuit provides a ground path for both the AIR solenoid and the AIR pump.