Ok, I remove the wiper switch from the bezel and I jumped a wire in the last connector (out of the three) on the right of the plug (not the wiper switch but the plug coming out of the wiring harness). I jumped it by grounding it to one of the bezel screws.

The wiper door still did not activate, but the "wiper override" indicator on the bezel lit up

When I jumped the middle plug, nothing happened at all.

I disconneted the wiper override switch under the dash under the steering wheel and tried jumping the plug again. The wiper override indicator still came on.

Maybe I'm not jumping it correctly??? Should I be placing a wire between the switch and the harness connector???

At any rate, if I assume that both my switches are working correctly, where should I look next? Could the componenet located at the tach not be working properly? I really wish I knew what I was doing just this once

***Original post***

Guys,

My wiper system (68 vert 327/350) was working fine until yesterday. The switch does not activate the wiper door anymore, but the override stich under the dash opens it right up with no problems.

Could this point to a bad switch? Are there any other obvious places to look?

This has happened off and on over the last year. The wiper system will work for six months and then mysteriously stop for a while.

Any help would be appreciated as usual

 

Have you checked that the microswitch on the firewall (next to the wiper door actuator) is working correctly? There is a home made looking arm that comes out of the cowl cahnnel and has a right angle piece attached to it. The end of the right angled piece has a bolt screwed through it (looks like a carriage bolt) that is adjustable. Adjust the length to correctly contact the microswitch.

The microswitch itself could be failing also - you can test this by connecting a jumper wire with alligator clips to both ends of the switch to bypass it.

Just be careful working with this because when the microswitch is jumpered, the wipers WILL operate with the door closed and crash into the door!

 

Thanks. I was wondering about the microswitch. The bolt that you talk about is adjusted out about 1/2 inch from the switch. When I flip the wiper switch, should the bolt make contact with the switch somehow???

 

Yes, the bolt should contact the switch but only when the wiper door is fully open.

 

Check to see if your switch is grounded.I think it relys on the gauge cluster housing for a ground.If your housing is cracked at the breakaway thin spots just below the air duct this could be your problem.I'll check my wiring diagram for a ground source and get back to you.

 

the micro is after the signal from the switch--- it tells the wiper motor to run after the door is up.

 

As others have stated, the bolt head needs to push the microswitch in when the door is FULLY open.

Here's the sequence:

Turn wiper switch on
- Electric Vacuum relay [attached to back of Tach] engages and enables vacuum to wiper door system <<-- this could have issues from what you describe
- Wiper door opens
- When door is fully open, microswitch closes
- Wipers come on

Turn switch off
- Wipers park [and contact vacuum switch in passenger side cowl well]
- When wipers are fully parked and above vacuum switch is FULLY pressed, vacuum is enabled to wiper door actuator
- Microswitch OPENS disabling the wiper motor
- Wiper door closes

Make sure the ground to the wiper motor is solid - this can also intermittently prevent the wipers from coming on (but the door WILL open).

 

Just for fun take a wire and ground it(and make sure it is grounded) and touch it to the housing that holds the wiper switch.If they work then your switch has no ground---this is what I find 9 out of 10 times.

 

Thanks guys. I'll try all suggestions tonight. My gauge bezel is busted just above the cluster so this may be the cause if this is, in fact, the ground.

That's the one thing I love about my vette...There's always something to fix

 

Ground---can not prove by wiring schematic that the switch grounds through the housing but I went out in the shop and removed the switch from the housing of a 69 and it would not operate.The switch signals a vacumn solenoid that is attached to the back side of the tach that signals a vacumn relay that signals the wiper door actuator to open the door then that micro comes into play.Good Luck Qs 68

 

Ya think....

 

Sorry didn't mean to repeat what you said.

 

I had this exact problem last week. I went through everything, the vacuum solinoid behind the tach, the relay in the console(70-72). Finally I pulled the switch, checked it with a test light to verify it was changing power from pole to pole, everything checked out ok.. Put it back together then all of the sudden my wipers started working again. Mine was doing the same thing, the wiper door would not open nor would the wipers come, even if i manually opened the wiper door via bypass. If the system is doing nothing at all, start with the main wiper switch and ground. On 70-72s there is a relay on the right side of the console that also wires into the circuit for the wipers.

 

I think PWS69 may be the winner. If the harness is ok, which I think it is and the switches are both functional, which I think they are, it's probable that the electric vacuum relay is bad???

The million dollar question...How hard is it to test this relay or replace it???

Thanks PWS69 and everyone!

 

PWS69 is the on the ball on wipers, windshield, ect He has been a great help on my windshield questions . Note the 68 system is uniqute to 68 and different from the 69-72 system. If a wire vacuum diagram is needed I have them needed, AL.

 

Well, I fixed my wipers yesterday. The funny thing is, I have NO idea what the heck I did!

I moved the switch all the way over to "high", pulled the door override and then I jiggled the two wires running into the motor and then lightly tugged on the wiper transmission arms and they sprung to life!

This leads me to believe I have an electrical or grounding issue somewhere at the motor, but I'm not sure where.

If anyone needs help pulling on any wires or connections, give me a ring. I seem to have the magic touch

Thanks to everyone for the suggestions!

 

Be glad it's a possible motor issue (I'm guessing park contact or brushes in the motor - may never happen again). You do not want anything to go wrong with that tach mounted vacuum solenoid, as they are made of high-grade unobtanium. Be VERY nice to this if you need to work in that area.

I agree that the bezel ground is most often the problem foe a variety of ills on this system. I run a seperate ground wire to solve this, even when the bezel is in one piece.

Hans

 

I wasn't aware of the rarity of the vacuum solenoid under the tach! It shouldn't surprise me anymore becasue just about everything I've had to replace has been unobtainable.

I actually pulled it and cleaned the contacts and got it back in with little difficulty. I'll file it under the "don't ever break" category