Part 2

Checking the vacuum system (Continued)

Checking for an open-circuit




- Ignition off.








- Check the cable between vacuum pump connector terminal #3 and control module connector terminal #1 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.





Continue - Verification of the governor

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Checking the governor








- Ignition off.
- Vacuum pump removed.




- Temporarily connect a cable between vacuum pump pin terminal #3 and the battery positive terminal. Connect a cable between vacuum pump pin terminal #1 and the battery negative terminal. The governor should click.
- Remove the temporarily connected cables.

Did the governor click?

Yes - Checking for contact resistance and oxidation

No - Replacing the component

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Checking for contact resistance and oxidation




- Ignition off.
- Check the control module terminal and vacuum pump connectors for contact resistance and oxidation and for loose connections. Remedy contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Remedy loose connections according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.





Continue - Verification of the governor

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Replacing the component




- Ignition off.
- Replace the vacuum pump according to Vacuum pump and regulator Service and Repair.





Continue - Verification of the governor

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Checking the function of the vacuum pump








- Ignition on.
- Control module disconnected.
- Connect the single wire cable between terminals #1 and #11 on the control module connector.
Connect the other cable with the double flat pin to control module connector terminal #10. Connect one of the other ends to control module connector terminal #12.
Connect the other cable to control module connector terminal #9. The vacuum pump should start. The vacuum regulator should compress.
Remove the cable from terminal #9 when the vacuum regulator is fully compressed. The vacuum pump should stop.





Is the vacuum pump operating normally?

Yes - No Fault Found

No - Checking the cable to the vacuum pump

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Checking that the vacuum system is air tight












- Ignition off.
- Control module disconnected.
- Vacuum pump connected.
- Ignition on.
- Connect the single wire cable between terminals #11 and #1 on the control module connector.
Connect the other cable with the double flat pin to control module connector terminal #10. Connect one of the other ends to control module connector terminal #12.
Connect the other cable to control module connector terminal #9. The vacuum pump should start. The vacuum regulator should compress.
Remove the cable from terminal #9 when the vacuum regulator is fully compressed. The vacuum pump should stop.
The vacuum system is airtight if the vacuum regulator has not released the throttle mechanism after 30 seconds.




- Disconnect the cable connected to control module connector terminal #12. The vacuum regulator will then release the throttle mechanism.

Is the vacuum system airtight?

Yes - Checking brake valves

No - Checking for leaks

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Checking for leaks
- Check that there are no leaks in the hoses to the vacuum pump and the vacuum regulator.

Continue - Checking brake valves

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Checking the cable to the vacuum pump












- Ignition off.
- Disconnect the vacuum pump.
- Control module disconnected.
Connect a voltmeter between vacuum pump connector terminal #2 and ground.









The ohmmeter should read infinite resistance.

OK - Checking the voltage to the vacuum pump

Not OK - Checking for a short-circuit

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Checking for a short-circuit




- Ignition off.








- Check the cable between vacuum pump connector terminal #2 and control module connector terminal #9 for a short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.





Continue - Verification of the vacuum pump

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