Vacuum Pump

Check the vacuum pump.
a. If vacuum lines are OK, replace the EGR valve vacuum transducer.
b. With the engine off, disconnect the 2 pin plug on the vacuum transducer (Y31/1), and check to see that there is battery voltage at the plug.
1. If there is no voltage, repair wiring.
2. If voltage is present, replace EDS control unit.
c. Connect a vacuum gauge, with a 'T' fitting, to the EGR valve and note the reading with the engine running at 1200 rpm. When accelerating briefly, vacuum reading should drop.
1. If vacuum does not drop, replace vacuum transducer.
2. Check air flow sensor for proper mechanical operation.
3. If all other components test OK, replace the EDS control unit.