Need help with electrical component of wipers on a 69

[Michael L.]

Guys

I'm still working on my wipers for my 69 L-46 resto. I've made progress on the vacuum side of the system, but I can't seem to get the wiper motor to run. I've checked the fuse and replaced the wiper switch but no luck. I've looked at a number of old threads that discuss the wiper system and I've looked at all the service manuals I have but I still don't have a clear idea of how to troubleshoot the wiper motor. One specific question I have is do I need vacuum to run the wipers if the wiper door switch is already open? i.e. does the WSW solenoid require vacuum to complete an electrical circuit, or does it require electricity to complete a vacuum circuit? Any assistance is greatly appreciated.

Mike

[Mark E.]

Re: Need help with electrical component of wipers on a 69

Mike,

Check that the motor is getting power and is grounded. Power goes through the wiper door limit switch. It's mounted on plenum wall with two red/white wires, and is mechanically connected to the wiper door. It breaks the circuit to the motor unless the wiper door is open.

The vacuum and electrical systems are separate: Vacuum to open and close wiper door, and electrics to power the wipers.

[David H.]

Re: Need help with electrical component of wipers on a 69

Mike

Perhaps some help here on Willcox Corvette site:

http://repairs.willcoxcorvette.com/1968-1976-corvette-wiper-motor-test/

http://repairs.willcoxcorvette.com/wp-content/uploads/2009/03/1969-1972-corvette-windshield-wiper-motor-wire-schematic-69-72-with-test.pdf

Dave

[Jeffrey S.]

Re: Need help with electrical component of wipers on a 69

Mike,
Have you tried to operate the wiper motor with a door open? This may sound strange but many years ago the wiper motor on my '69 would not run. I replaced the motor and, when I tried it with the door open it ran. Problem solved right? Not so fast. When I drove the car and needed the wipers they would not run. I found that the ground is at the starter and this wire was broken. By opening a door the wipers grounded through the door/alarm which is grounded through the alarm. The alarm ground is piggy backed on the wiper ground plug.
Just a thought.
Jeff

[Michael L.]

Re: Need help with electrical component of wipers on a 69

Thanks for the tips, Guys. Can you tell me what the answer is to the question I posted above? Does the WSW solenoid require vacuum to complete an electrical circuit, or does it require electricity to complete a vacuum circuit?

Mike

[Michael L.]

Re: Need help with electrical component of wipers on a 69

Guys,

I tried to bypass all the wiring to test the motor itself. I grounded the unit directly to the engine from what I think is the ground on the top of the motor casing (see attached picture). Then I disconnected the door limit switch harness and tried 12V from the battery directly to both sides of the door limit switch and the motor did not work. Does this definitively prove the motor is bad? Is the ground for the wiper motor the ground on the top of the casing seen in my photo? Or is that the ground for the wsw pump? Is there a different ground for the wsw motor? As always thanks so much for your assistance.

Mike

IMG_4615.jpg

[David H.]

Re: Need help with electrical component of wipers on a 69

Thanks for the tips, Guys. Can you tell me what the answer is to the question I posted above? Does the WSW solenoid require vacuum to complete an electrical circuit, or does it require electricity to complete a vacuum circuit? Mike

Mike

Link below is to GM Service Manual System Wiper System Rebuild. Page 12-51 has words & music relative to vacuum/electrical system interface. My read is you need vacuum to allow wiper motor to turn on - this prevents systems interfering with one another re Interlock Switch.

Dave

https://drive.google.com/file/d/0B280la3_R5t9U0VzSjVvdFBWdFk/view

[Mark E.]

Re: Need help with electrical component of wipers on a 69

Dave,

The interlock switch directs vacuum to the wiper door vacuum relay based on the position of the wiper door. It doesn't have any electrical connections, nor control the wiper motor.

The limit switch opens/closes the electrical circuit to the motor based on the position of the wiper door. It doesn't have any vacuum connections.


Mike,

If someone doesn't reply first, I'll check the wiring and ground for the motor for you.

[Michael L.]

Re: Need help with electrical component of wipers on a 69

Dave,

The interlock switch directs vacuum to the vacuum relay based on the position of the wiper door. It doesn't have any electrical connections, nor control the wiper motor.

The limit switch opens/closes the electrical circuit to the motor based on the position of the wiper door. It doesn't have any vacuum connections.


Mike,

If someone doesn't reply first, I'll check the wiring and ground for the motor for you.

Sorry Mark, I wasn't clear. What I'm asking about is the wsw solenoid that is mounted behind the tachometer. It has both an electrical connection and a vacuum connection. What's controlling what with that switch?

Mike

[Mark E.]

Re: Need help with electrical component of wipers on a 69

Sorry Mark, I wasn't clear. What I'm asking about is the wsw solenoid that is mounted behind the tachometer. It has both an electrical connection and a vacuum connection. What's controlling what with that switch?

Mike

That's the wiper door "Vacuum Control Solenoid". When the solenoid is energized by turning on the wiper dash switch it blocks vacuum to the relay valve to open the wiper door. It's in series with the wiper "Vacuum Over-Ride Valve" (the manual push/pull below the steering column) and the "Interlock Valve" (discussed above). All three of these need to pass vacuum to close the wiper door. In other words, the wiper door opens if any of these block vacuum.

This solenoid is working if your wiper door is opening and closing properly. (That's why I didn't mention it earlier. Sorry for any confusion.)

WillcoxCorvette.com has great color schematics of the vacuum system. Beware that the schematic in the 1970 (1969 Corvette) Service Manual is WRONG (page 12-46).

[Michael L.]

Re: Need help with electrical component of wipers on a 69

Thanks Mark. I think I have a handle on the vacuum system and I have a number of schematics for it including the one from Willcox. What I'm trying to do now is figure out why the wiper motor won't run. I just wanted to make sure it couldn't be the VCS but clearly it's not. I was unable to get the video's to load at my shop that David was kind enough to attach in an earlier post but now that I'm in my office today I'll review those to see if I can figure this out.

Mike

[David H.]

Re: Need help with electrical component of wipers on a 69

Mike

Off the wall.

Was your starter replaced during restoration?

Does your blower motor also NOT work?

Any chance the black ground wire for engine harness has been connected to starter's positive battery cable connection?

Dave

[Michael L.]

Re: Need help with electrical component of wipers on a 69

Guys,

Sorry for the delay. I was away for a week and I'm back at it now. David, the starter was replaced during the resto. Can't say if the blower motor works or not as its controls haven't been installed yet. The black ground wire at the starter for the engine harness is connected to the starter mounting bolt as it should be.

In trying to work through this I've noted that there isn't any power coming in to the wiper door limit switch from the #12 R/W stripe wire that is supposed to supply the 12V for the motor. The fuse is good in the fuse box. Can you tell me if there is supposed to be power to that switch constantly and the circuit is complete only when the wiper door is open or does something else have to happen to send power to it? I've been reading that the wiper motor is similar to the door lights and is operated when a ground is made when the switch is turned on which completes the circuit so I'm wondering if the problem is lack of 12V input to the motor although when I tried sending 12V directly to the wiper motor through the #12 R/W wire with a test wire nothing happened. Any thoughts?

[David H.]

Re: Need help with electrical component of wipers on a 69

Guys,

Sorry for the delay. I was away for a week and I'm back at it now. David, the starter was replaced during the resto. Can't say if the blower motor works or not as its controls haven't been installed yet. The black ground wire at the starter for the engine harness is connected to the starter mounting bolt as it should be.

In trying to work through this I've noted that there isn't any power coming in to the wiper door limit switch from the #12 R/W stripe wire that is supposed to supply the 12V for the motor. The fuse is good in the fuse box. Can you tell me if there is supposed to be power to that switch constantly and the circuit is complete only when the wiper door is open or does something else have to happen to send power to it? I've been reading that the wiper motor is similar to the door lights and is operated when a ground is made when the switch is turned on which completes the circuit so I'm wondering if the problem is lack of 12V input to the motor although when I tried sending 12V directly to the wiper motor through the #12 R/W wire with a test wire nothing happened. Any thoughts?

Mike

Attached is a wiper system diagram from a non GM source. Of course wiring colors don't match with GM document, but it does limit extraneous lines. From this diagram looks like SWITCHED (Hot in Run or Accessory) power from wiper fuse feeds wiper door solenoid, etc. HOT AT ALL TIMES feeds "wiper door override switch (WDOS)". Power to WDOS controls power to "Limit Switch". Hope this helps.1969-70 wiper.jpg

Dave

[Michael L.]

Re: Need help with electrical component of wipers on a 69

Thanks Dave. I used a service bulletin (I think) to "bench test" the motor even though I left it in the car and the motor works perfectly which is a relief because at least I know it works. Now the problem seems to be that the RH wiper arm, although it unmistakably moves to the park position, does not recede into the cowl enough to depress the wiper door safety valve so the wiper door can close. It's as if the wiper arm isn't mounted on the shaft at the right angle, although I'm not sure if this can be adjusted.

Anyone ever see this problem?

Mike