Checking Vacuum Pump
Checking the vacuum pump
Fault-tracing information
The vacuum pump raises the power brake booster efficiency when the negative pressure of the engine is too low, e.g. when the engine is switched off (ignition on).
Operating difficulties may make the brake pedal stiff.
Reasons for the vacuum pump not working can include:
- Open-circuit, short-circuit in the wiring to the vacuum pump
- Damaged switch for vacuum pump.
- Damaged vacuum pump.
Causes for vacuum pump running constantly can be:
- Short-circuit to supply voltage in the cable to the vacuum pump
- Damaged switch for vacuum pump.
- Damaged vacuum hoses for vacuum pump.
Continue - Check the function of the vacuum pump
-------------------------------------------------
Check the function of the vacuum pump
- Ignition off
- Check the hoses and connections. Check for leakage
- Before the next corrective action - wait approximately 3 minutes after switching the ignition off (system relay disconnected).
Pump the brake pedal a few times to that all negative pressure in the power brake booster disappears.
Check the function of the vacuum pump by pressing the brake pedal with the ignition on. The Vacuum pump should start and run for a few seconds to build up a new vacuum and then stop.
Select an option:
1. The vacuum pump is functioning normally
2. The vacuum pump is operating constantly
3. The vacuum pump is not operating.
1 - No Fault Found
2 - Checking the wiring
3 - Checking the wiring
-------------------------------------------------
Checking the wiring
- Ignition off.
Check the fuse for the vacuum pump in the integrated relay/fusebox in the engine compartment. If the fuse is blown, check the cable for power supply between vacuum pump switch terminal #1 and the fuse. Check the cable between vacuum pump switch terminal #2 and vacuum pump connector terminal #1. Check for an open-circuit or short-circuit to ground.
Check the function of the vacuum pump switch. With the ignition on, connect a temporary cable looped between terminals #1 and #2 on the connector for the switch (vacuum pump side). If the vacuum pump starts, replace the switch.
If the vacuum pump does not start, measure the resistance to vacuum pump terminals #1 and #2. If there is infinite resistance, there is an open-circuit in the vacuum pump or in the cable between the vacuum pump and the connector. If the resistance is 0 ohms there is a short-circuit in the vacuum pump or in the cable between the vacuum pump and connector.
Remedy as necessary.
Other information:
- Checking wiring and terminals Checking Wiring and Terminals
Continue - Verification
-------------------------------------------------
Checking the wiring
- Ignition off.
Check the cable for power supply between the vacuum pump switch terminal #2 and vacuum pump connector terminal #1. Check for a short-circuit to supply voltage.
Hint: Check the switch for the vacuum pump by measuring the resistance between terminals #1 and #2. The resistance must be infinite.
Remedy as necessary.
Other information:
- Checking wiring and terminals Checking Wiring and Terminals
Continue - Verification
-------------------------------------------------
Verification
Hint: After carrying out the repair, check that the fault has been remedied.
- Ignition off
- Before the next corrective action - wait approximately 3 minutes after switching the ignition off (system relay disconnected).
Pump the brake pedal a few times to that all negative pressure in the power brake booster disappears.
Check the function of the vacuum pump by pressing the brake pedal with the ignition on. The Vacuum pump should start and run for a few seconds to build up a new vacuum and then stop.
Is the function correct?
Yes - FAULT FOUND
No - Fault-tracing information
-------------------------------------------------
Fault-tracing information
Information
Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.
Do you want to exit fault-tracing?
Yes - Exit fault-tracing
No - Attempt New Test
------------------------
Attempt New Test - Fault-tracing information
-------------------------------------------------