Note. Introduction of recirculated exhaust gas into combustion chamber is used to lower formation of oxides of nitrogen by lowering peak combustion temperature. ECM controls EGR solenoid and allows exhaust gas to flow when EGR solenoid is turned on. ECM controls timing duration of EGR solenoid on time according to engine speed, engine vacuum, exhaust system back pressure, coolant temperature and throttle position. ECM monitors operation of solenoid by looking for expected coil surge voltage (system voltage plus 2 volts) when EGR solenoid is turned off.
Diagnostic Aids
EGR solenoid coil surge voltage (system voltage, plus 2 volts) has not been detected when solenoid is turned on / off.
Check for following possible problems
- EGR solenoid failed.
- Open or short in EGR solenoid circuit, or loose connector.
- ECM failed.