Emission Control System

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Georgia Boyd
5 years ago
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1 Emission Control System Exhaust Gas Recirculation System Troubleshooting Flowchart Self diagnosis indicates code 12: Most likely a problem in the Exhaust Gas Recirculation (EGR) system. The EGR System is designed to reduce oxides of nitrogen emissions (NOx) by recirculating exhaust gas through the EGR valve and the intake manifold into the combustion chambers. It is composed of the EGR valve, CVC valve, EGR control solenoid valve, PGM-FI ECU and various sensors. The ECU contains memories for ideal EGR valve lifts for varying operating conditions. The EGR valve lift sensor detects the amount of EGR valve lift and sends the information to the ECU. The ECU then compares it with the ideal EGR valve lift which is determined by signals sent from the other sensors. If there is any difference between the two, the ECU cuts current to the EGR control solenoid valve to reduce vacuum applied to the EGR valve. EGR VALVE LIFT SENSOR EGR CONTROL SOLENOID VALVE EGR VALVE CVC VALVE AIR CHAMBER TO No. 2 FUSE ECU MAP SENSOR TDC/CRANE/CYL SENSOR THROTTLE ANGLE SENSOR TW SENSOR

2 Check Engine warning light has been reported on. LED indicates CODE 12. Turn the ignition switch OFF. Remove the BACK UP fuse in the under-hood relay box for 10 seconds to reset ECU. Road test necessary: Warm up the engine to normal operating temperature (cooling fan comes on). Drive the car on the road for approx. 10 minutes. Try to keep the engine speed in the range. Is Check Engine warning light on and does LED indicated CODE 12? With the engine at idle, disconnect the #16 hose from the EGR valve and connect a vacuum pump/ gauge to the hose. Intermittent failure, system is OK at this time. Check for poor connections or loose wires at EGR valve C117, C210 (located at right shock tower), C311 (located at left shock tower), control box. #16 HOSE VACUUM PUMP/GAUGE A973X 041 XXXXX EGR VALVE Is there any vacuum? Disconnect 4P connector from the control box and check the #16 hose for vacuum again. Move the vacuum pump/gauge to the EGR valve. PNK #16 HOSE EGR VALVE (To page ) (To page ) (cont'd)

3 Emission Control System Exhaust Gas Recirculation System (cont'd) (From page ) With the engine at idle, apply 8" of vacuum to the EGR valve. (From page ) Is there any vacuum? Check vacuum hose routing of the entire EGR system. If hose routing is OK, replace EGR control solenoid valve. Inspect for short to body ground in PNK wire between EGR control solenoid valve and ECU (A11). If wire is OK, substitute a known-good ECU and retest. If symptom/indication goes away, replace the original ECU. BLK/YEL Does the engine stall and does the EGR valve hold vacuum? Replace EGR valve. Disconnect the 4P connector from the control box. Measure voltage between BLK/ YEL (+) terminal on the main wire harness and body ground. Is there battery voltage? Repair open in BLK/YEL wire between the solenoid valve and No.2 fuse. Reconnect the vacuum gauge to the #16 hose. pump/ Start the engine and allow it to idle. (To page )

4 (From page ) A( + ) B( ) Connect the battery positive terminal to the A terminal of the 4P connector. While watching the vacuum gauge, connect the battery negative terminal to the B terminal. Is there approx. 8" within 1 second? Turn the ignition switch OFF and inspect the #16 and #24 hoses for leaks, restrictions, or mis-routing. Turn the ignition switch OFF and reconnect the 4P connector. Are the hoses OK? Connect as necessary. CV C VALVE EGR CONTROL SOLENOID VALVE TEST HARNESS 07JAZ A Disconnect the lower hose on EGR control solenoid valve and connect a vacuum gauge to the hose. Start the engine and allow it to idle. AIR VACUUM CHAMBER PUMP/GAUGE A973X 041 XXXXX Is there 6" 10" of vacuum? Replace CVC valve. Connect the test harness between the EGR valve lift sensor and engine wire harness. Replace the EGR control solenoid valve. Turn the ignition switch ON. Measure voltage between RED ( + ) terminal and GRN ( ) terminal. Is there approx. 5 V? (To page ) Repair open in YEL/WHT wire between EGR valve and ECU (D20). Repair open in GRN/WHT wire between EGR valve and ECU (D22). (cont'd)

5 Emission Control System Exhaust Gas Recirculation System (cont'd) (From page ) Measure voltage between WHT ( + ) terminal and GRN ( - ) terminal. Is there approx 1.2 V? While watching the voltmeter, slowly apply a continuous 8" of vacuum to the EGR valve. Repeat several times, completely releasing vacuum between. Replace EGR valve. Repair short in WHT/BLK* wire between ECU (D12) and EGR valve lift sensor. Substitute a known-good ECU and recheck. If prescribed voltage is now available, replace the original ECU. *: YEL on early production. Is the maximum voltage approx. 4 V? Replace EGR valve. Does the voltage consistently increase/decrease as the vacuum increases/decreases? Replace EGR valve. Reconnect the #16 hose to the EGR valve. Turn the ignition switch OFF. Connect the ECU test harness between the ECU and connector (page 11-18). Start the engine and allow it to idle. (To page )

6 (From page ) Measure voltage between D12 ( + ) terminal and D22 (-) terminal. D12 < + ) D22 (-) 1 V? Is there approx. 1.2 V? Repair open in WHT/BLK* wire between ECU (D12) and the sensor. *: YEL on early production. Connect A11 terminal to A26 terminal with a jumper wire. Did the engine stall? Repair open in PNK wire between ECU(A11) and EGR control solenoid valve. Substitute a known-good ECU and recheck. If symptom/indication goes away, replace the original ECU.

Emission Control System

Emission Control System Exhaust Gas Recirculation (EGR) System [B18A1 engine: A/T] Troubleshooting Flowchart The Malfunction Indicator Lamp (MIL) indicates Diagnostic Trouble Code (DTC) 12: A problem in