Checking Air Pump System

FAULT TRACING INFORMATION

Preconditions
^ DTCs absent.
^ Fault permanent.

Fault Sources
^ Signal lead short circuited to ground.
^ Signal lead short circuited to live.
^ Air pump power lead short circuited to live.
^ Magnetic valve power lead short circuited to live.
^ Break in signal lead.
^ Break in relay power lead.
^ Break in relay ground lead.
^ Break in magnetic valve live or ground lead.
^ Break in air pump live or ground lead.
^ Defective air pump.
^ Defective air pump relay.
^ Defective magnetic valve.
^ Blocked hoses.

TESTING PROCEDURE





Symptom:

IF air pump runs continually:
- Proceed to: Check Signal Lead Resistance to Ground, section below.
If above symptom does not occur:
- Check Air Pump.





Check Air Pump
^ Check, using Diagnostic Test Mode 3, if air pump will operate.

If air pump activated:
- Proceed to: Check Magnetic Valve, section below.
If air pump not activated:
- Proceed to: Check Fuse, section below.





Check Signal Load Resistance to Ground
^ Ignition OFF.
^ Disconnect air pump relay in central relay unit position A.
^ Connect an ohmmeter between relay base contact 4 and ground.

Ohmmeter should read approx. 27K ohms.

If value OK:
- Proceed to: Check Power Lead to Magnetic Valve, section below.
If value differs:
- Check lead between relay base contact 4 and ECM 5 for short circuit to ground.





Check Power Load to Magnetic Valve
^ Ignition OFF.
^ Disconnect magnetic valve.
^ Ignition ON.
^ Connect a voltmeter between magnetic valve connector contact 1 and ground.

Voltmeter should read approx. 0 Volts.

If value OK:
- Proceed to: Check Power Lead to Air Pump, section below.
If value differs:
- Check lead between magnet valve contact 1 and relay base contact 3 for short circuit to live.





Check Power Lead to Air Pump
^ Ignition OFF.
^ Disconnect air pump.
^ Ignition ON.
^ Connect a voltmeter between air pump connector contact 2 and ground.

Voltmeter should read approx. 0 Volts.

If value OK:
- Test with a new air pump relay.
If value differs:
- Check lead between air pump contact 2 and relay base contact 3 for short circuit to live.





Check Magnetic Valve
^ Ignition OFF.
^ Disconnect magnetic valve.
^ Connect an ohmmeter between magnetic valve pins 1 and 2.

Ohmmeter should read approx. 35 ohms.

If value OK:
- Proceed to: Check Magnetic Valve Ground Lead, section below.
If value differs:
- Test with a new magnetic valve.





Check Magnetic Valve Ground Lead
^ Ignition OFF.
^ Magnetic valve disconnected.
^ Connect an ohmmeter between magnetic valve connector contact 2 and ground.

Ohmmeter should read approx. 0 ohms.

If value OK:
- Proceed to: Check Fuse, section below.
If value differs:
- Check lead between magnetic valve contact 2 and 20-pin connector, junction box in central relay unit (34/42) contact 12 for break.





Check Fuse
^ Check if fuse 2 (11B/2) in central relay unit is OK.

If fuse OK:
- Proceed to: Check Magnetic Valve Power Lead, section below.
If fuse not OK:
- Check lead between magnetic valve contact 1 and relay base contact 3 for short circuit to ground.





Check Magnetic Valve Power Lead
^ Ignition OFF.
^ Magnetic valve disconnected.
^ Connect an ohmmeter between magnetic valve connector contact 1 and ground.

Ohmmeter should read approx. 0 ohms.

If value OK:
- Proceed to: Check Hoses, section below.
If value differs:
- Check lead between magnetic valve contact 1 and relay base contact 3 for break.





Check Hoses
^ Check with vacuum that pump hoses are not blocked or leaking.
^ Check hoses from air pump are not pinched or frayed.
^ Check air pump intake not blocked.
^ Check air pump blows air when operating.
^ Check shut-off valve opens under negative pressure in vacuum connections.
^ Check non-return valve not binding or blocked.





Check Fuse
^ Check if fuse 6 (11A/6) in main fuse box behind battery is OK.

If fuse OK:
- Proceed to: Check Air Pump Relay Power Lead, section below.
If fuse not OK:
- Check lead between relay base contact 1 and fuse for short circuit to ground.





Check Air Pump Relay Power Lead
^ Ignition OFF.
^ Disconnect air pump relay in central relay unit position A.
^ Ignition ON.
^ Connect a voltmeter between relay base contact 1 and ground.

Voltmeter should read battery voltage.

If value OK:
- Proceed to: Check Signal Lead, section below.
If value differs:
- Check lead between relay base contact 1 and fuse for break.





Check Signal Lead
^ Ignition OFF.
^ Air pump relay disconnected.
^ Ignition ON.
^ Connect a voltmeter between relay base contact 4 and ground.

Voltmeter should read approx. 0 Volts.

If value OK:
- Proceed to: Check Signal Lead Resistance, section below.
If value differs:
- Check lead between relay base contact 4 and ECM 5 for short circuit to live.





Check Signal Lead Resistance
^ Ignition OFF.
^ Air pump relay disconnected.
^ Connect an ohmmeter between relay base contact 4 and ground.

Ohmmeter should read approx. 27K ohms.

If value OK:
- Proceed to: Check Air Pump Ground Lead, section below.
If value differs:
- Check lead between relay base contact 4 and ECM 5 for break.





Check Air Pump Ground Lead
^ Ignition OFF.
^ Disconnect air pump.
^ Connect an ohmmeter between air pump connector contact 1 and ground.

Ohmmeter should read approx. 0 ohms.

If value OK:
- Proceed to: Check Air Pump Power Lead, section below.
If value differs:
- Check lead between air pump contact 1 and control point at upper front fender (31/1) for break.





Check Air Pump Power Lead
^ Ignition OFF.
^ Disconnect air pump relay in central relay unit position A.
^ Air pump disconnected.
^ Connect an ohmmeter between relay base contact 3 and air pump connector contact 2.

Ohmmeter should read approx. 0 ohms.

If value OK:
- Proceed to: Check Air Pump Relay, section below.
If value differs:
- Check lead between relay base contact 3 and air pump contact 2 for break.





Check Air Pump Relay
^ Air pump disconnected.
^ Ignition ON.
^ Connect a voltmeter between air pump connector contact 2 and ground.
^ Check relay function using Diagnostic Test Mode 3.

Voltmeter should flip from 0 Volts to battery voltage when air pump relay tries to activate air pump.

If voltmeter flips from 0 Volts to battery voltage:
- Test with a new air pump.
If voltmeter reads 0 Volts:
- Test with a new air pump relay.