Dave J

There is no need to pull the dash pad to simply check the hose routing, or test the components behind the dash if that's all you wish to do. If you have a '72 assembly manual it will be the same for a '71. Simply get under the dash and using your hands and fingers, follow the hoses and check the connections.

Small hose from check valve - "T" connection splitting to (1)headlight switch, (2) straight port on electrical connection side of solenoid (5 o'clock position on back of tach).

90 degree port on other side of solenoid (straight port is a vent) to the port closest to the pull on the over ride switch.

Port farthest from the pull on the over ride to the middle port on the wiper safety valve (usually red)

Lower port on safety valve (usually white) to the top port on wiper door relay.

Dave J

BLUE1972

The switch that operates the wiper vac system, attached to the back of the tech.

The diagrams show 2 vac lines, mine has 3. which is incorrect (I think)
I don't want to mess with my 72 as it's all original and 22k miles.

This weekend I'm pulling the dash (if no rain) and tracing all the vac lines.
No Vac the door opens. (fail safe condition),

The switch is hanging down. The previous owner was 80ish and "fixed" a few things over the 30+yeaars he had it. There are 2 T fittings under the dash? which is incorrect as I did not see them on the 72.

0Willcox Corvette

Are you talking about the tach solenoid on the back of the tach? If so, power and ground to it should block vacuum from passing through it.

Willcox

BLUE1972

THANKS,
too much rain and working the next few days. He has lines on both sides all ports on the solenoid valve. I'll have to check the valve and re route the vacuum lines. thanks
P.S I just removed the phone...and antenna for the phone.. don't ask.. Shaft would be proud.

I was an R&D engineer long time ago, we called the electric solenoid valves = electric sel switches - used them for water, oil and air.

BLUE1972

Pulled the dash today, found the headlight switch did not have vac hookup. Also found lines squished between the column and the mount.
Used Vacuum lines from auto Zone -matched the size. Put a Tee in where the headlight switch will go. PLUGGED OPEN SIDE OF TEE. Now everything is working properly.


also removed more wire from the Telephone hookup.
Got the turn signals working. Found an alarm under the dash. Many cut lines and many tie ins. Thank goodness I got new cutting pliers2 rolls of solder and lots of heat shrink tubing.


Next task is getting the headlight switch, of course the two local corvettes shops are OOS.
Probably will use RICKS - had good luck with them.
Can't wait to see what is under the center section.

I have never seen / found such a mess in my life.