EGR Electronic Vacuum Regulator Solenoid: Testing and Inspection

EGR FREQUENCY VALVE CONTROL SIGNAL CHECKING

The EGR frequency valve gets battery voltage, at terminal #1 of its harness connector from fuse #28 in fuse relay panel, whenever the fuel pump relay is energized (ignition ON). The ECU energizes the frequency valve by completing the circuit to ground.



1. Start engine and let run until it reaches normal operating temperature.

2. Turn ignition OFF and disconnect EGR frequency valve from its harness connector.

3. Connect DVM between frequency valve harness connector terminal #1 and engine ground.

4. Turn ignition ON and note voltage.

^ Should be battery voltage.

If not, check for:

a. Fuse #28 in fuse relay panel blown.
b. Open circuit between fuse #28 and EGR frequency valve harness connector terminal #1.

Reading Dwell/Duty Cycle (EGR Frequency Valve):

3. Bridge the #1 terminals of the connector halves with a jumper wire and connect parallel test lead between the #2 terminals as shown in diagram.

4. Connect positive lead of dwellmeter or duty cycle meter to parallel test lead as shown, and ground the negative lead to the engine. If using a dwellmeter, set to 4 cyl. scale.

5. Start engine and run at approx. 2,000 rpm. Note dwell or % duty cycle.

^ Should be approx. 18-36~ dwell (20-40% duty cycle) at 2,000 rpm. Duty cycle is first triggered at 1,800 rpm and will not read below that speed. Be sure engine speed is at least 2,000 rpm when testing.

If there is a duty cycle, connect vacuum gauge in place of EGR valve and repeat test.

^ When duty cycle appears on meter, vacuum gauge should show a vacuum signal to the EGR valve.

If there is a duty cycle but no vacuum reading, replace EGR frequency valve.

If there is a vacuum reading before the duty cycle is triggered, replace EGR frequency valve.

If there is no duty cycle, check for:

a. Open or grounded circuit between EGR frequency valve and ECU terminal 14D.

If no wiring problems are found and there is still no duty cycle signal, then the ECU is faulty (open or shorted ground circuit at ECU terminal 14D).