[Vwdiesel] OK, its a solenoid

[Sandy Cameron]

More on the solenoid.

I've found the wiring diagram for your car, and it is called

"altitude correction valve" (NOT attitude :*))

Probably operated by that gizmo near your fuel filter called the altitude
correction switch.
Is that where the red/blue wirecomes from?

To learn more about the switch, you would have to study the plumbing going
to it, and from where it comes. Bentley is silent about this device, and
Canadian cars don't have it. Bentley seems to give limited info on emissions
control. (there are so many different juridictions and solutions).

On the diagram, +12v comes from the "ignition on" rail (15) to the
barometric switch device, on a red/black wire, then to the solenoid valve on
the pump on the red/blue wire.

I suspect if you were driving in denver, and stomped on the pedal, it would
operate to limit fueling and reduce the smoke due to insufficient air (alas,
no turbo), thereby placating the smoke police.

Want to persue this any further? If you live in an annual emissions
inspection area, you may want to replace the valve to avoid visual
inspection embarassment. It would be fair to say that it probably would
never operate unless you were at high altitude, and heavy footed.

Here in Ontario, Canada, we have an emissions inspection every 2 years on
the little diesels where they stare at the exhaust pipe for 5 minutes and
watch for puffs of smoke. No puffs, free ticket.

They also look under the hood for obvious signs of tampering with emissions
control equipment, but never put it on a hoist or connect testing equipment.
Oh, and they check the fuel filler cap to make shure it is there, and is the
correct kind (no potatoes).

I still think it would be interesting to connect a small 12v bulb to the
solenoid wire, other end to ground, and place it where you could observe it
while driving, and note what conditions, if any, cause it to come on.

Sandy
VE3AAC