REPLACING THROTTLE BYPASS VALVE
Refer to Group 13 for electrically heated auxiliary
air valve.
Throttle bypass valve must be fully open at a
coolant temperature of -20°C (-4°F) and
closed at + 70°C (158°F).
Checking on Cold Engine:
Detach air hoses on collector and throttle housing,
and blow in air.
Air must flow through.
If air does not flow, throttle bypass valve is defective.
Checking on Warm Engine:
Pinch hose between throttle bypass valve and
collector with engine running at idle speed.
Engine speed must not change.
If engine speed changes, control piston (2) has
seized.
Replace throttle bypass valve.

Drain coolant.
Installation: Bleed cooling system 17 00 039.
Detach hoses.
Detach throttle bypass valve at housing.
Installation: Replace gasket.


17 00 039