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System Check (Tacoma)

  1. Remove cap and filter from top of EGR vacuum modulator. See Figure. Ensure filter is clean and in good condition. Clean filter with compressed air (if necessary).
  2. Reinstall filter and cap. Ensure filter is installed in EGR vacuum modulator with coarse side facing upward, away from EGR vacuum modulator. Using 3-way connector, install vacuum gauge in vacuum hose between top of EGR valve and EGR vacuum modulator. Perform STEP 1 in illustration. See Fig 1. Start engine. Ensure engine idles smoothly to ensure proper seating of EGR valve. Shut engine off.
  3. Connect Toyota hand-held tester or scan tool to data link connector No. 3 located at driver's side of instrument panel. See Figure. Hand-held tester or scan tool is used to read engine RPM. To test operation of EGR Vacuum Switching Valve (VSV) with engine cold, ensure engine coolant temperature is less than 122°F (50°C). Start engine. Increase and maintain engine speed at 3500 RPM. Ensure no vacuum reading is obtained on vacuum gauge with engine speed at 3500 RPM and EGR pipe is not hot.
  4. To test operation of EGR VSV and EGR vacuum modulator, shut engine off. This test procedure may be performed by using Toyota hand-held tester to operate EGR VSV, or by connecting vacuum hose from port "Q" on EGR vacuum modulator to EGR valve. If using hand-held tester, go to next step. If hand-held tester is not available, go to step  6.
  5. Select ACTIVE TEST MODE on hand-held tester so EGR VSV is closed. Start engine. Operate engine at 3500 RPM. Ensure a low vacuum reading is obtained on vacuum gauge with engine speed at 3500 RPM. Shut engine off. Remove hand-held tester, vacuum gauge and reconnect vacuum hoses. Go to step  8.
  6. Remove 3-way connector and small vacuum hose between port "Q" (single port) on EGR vacuum modulator and EGR valve. Perform STEP 2 in illustration. See Fig 1. This 3-way connector and small vacuum hose goes from EGR valve and EGR vacuum modulator to EGR VSV. Install plug in vacuum hose to EGR VSV.
  7. Connect vacuum hose from port "Q" on EGR vacuum modulator directly to EGR valve. See Fig 2. This will by-pass EGR VSV. Start engine. Operate engine at 3500 RPM. Ensure a low vacuum reading is obtained on vacuum gauge with engine speed at 3500 RPM. Shut engine off. Remove vacuum gauge and reconnect vacuum hoses. Go to next step.
  8. To check EGR valve operation, remove and plug vacuum hose at EGR valve. Start engine. Using vacuum pump, apply vacuum directly to EGR valve with engine idling. Engine should run rough or stall. If EGR system does not operate as described, each individual component should be tested.
Fig 1: Installing Vacuum Gauge (Tacoma)
G98G12605Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 2: Identifying Ports On EGR Vacuum Modulator (Tacoma)
G99A08317Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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