Disconnected Cable On Unidentified Engine Part On A Corolla D4D Diesel

[excalibur2811]

Hi All,

I am a more or less happy owner of a 2003 Toyota Corolla Saloon.The car has a D4D engine.

This morning I happened to open the bonnet to check on some repair bodywork that was carried out by the local agents and noticed that I appear to have a disconnected wire leading into a unit that sits just above the engine cover on my D4D engine; the part is circled in red on the image attached with this post.

Although I have the Haynes manual and have gone through it page by page I am still unable to identify what this part is and would really like to know whether I may be damaging my engine by even running it with the wire disconnected. To be honest i did use the car this morning and everything seemed to be working fine. Obviously if it is a critical component that can affect the health of the engine I will need to set an urgent appointment with the mechanic (or maybe sort it out myself).

Any ideas please?

Thanks.

[alan333]

Is it the fuel filter? Difficult to tell from the pic. If it is then it's possibly a water trap warning light and won't do any harm.

[avensisd4d786]

its not the fuel filter its official name is Vacuum Reservoir Sub–assy

INTAKE.pdf

[avensis rob]

ive seen this same setup on my car but not taken much notice of it.

if I remember correct it connects to vac pump on side of engine then goes through to bulkhead

I was thinking it done the OPPOSITE of an air compressor storing pressure

but

it stores more of a buffer for available vacum

for things like brake servo , waste gate actuation . any other vac operated diaphragm valves there may be

also am I correct in remembering there is a sensor on it aswell

possibly for a warning if vacuum becomes too low (dangerous) due to being part of brake circuit?

ill say again never followed the pipework or took any attention of it, would be interested what it actually is?

[avensis rob]

had a look at my car

looks like a basic vacuum tank as thought to give a bit of extra vacuum to the brake servo incase the engine cuts out and you still need a couple of pedals worth of brake assistance

just one hose from vac pump entering front

just one hose exit from side to brake servo

there may be a non return valve in there too to hold the vacuum for a time?

the sensor is a 1 wire sensor completing its circuit through the body so it is an on off pressure switch or vac switch.

clue is in the name that this is a vacuum system component so is a vacuum switch

never got my meter out or anything but I guess it just completes the negative circuit to a warning light or controle module trigger for dash display warning on more technical dashboard displays.