Hey guys. I'm a sometimes lurker, first time poster. So first off, thanks for sharing all the wisdom.

Amidst losing a rod bearing and some other insanity of my own making, I've been dealing with a series of wiper issues over the course of a year. Without going through all the ups and downs and timeframe of it all, what I'm left with is this: I have a new wiper switch and delay module from Zip, and a wiper motor that is *supposed* to be a delay unit that is reman from Cardone. Everything works except the delay function; delay works the same as low speed, just runs nonstop. My wiper switch is grounding out the delay tab properly, the potentiometer is reading (don't know if it's reading correctly, but the value is changing), and the delay module is getting both those signals. I cleaned up the old switch, and there's no difference with that one. Shorting out the pot wires does nothing, didn't try shorting the signal to ground. Out at the motor, I hooked a lab scope to the delay wire in the cover, and I'm not seeing much of a signal change. It kind of rolls from 10V to 12V, not a hard ping to voltage or ground like I'm used to seeing. If I remember correctly, the wire has voltage when I unplug it, feeding it 12V does nothing and grounding it runs the washer pump. The cover is my stock one, the reman motor didn't come with a new one. I cleaned up the tab on the end of the delay arm, didn't make a difference.

I don't have a lot of high-end repair info available on this car. I'm open to suggestions or ideas, but I do have a few lingering questions if anyone has partial info.
What kind of signal am I supposed to see coming out of the wiper motor delay wire?
What should the ohm range of the delay pot at the switch be?
Is there a way to logic test the delay module?

Thanks for all your help, and thanks even if you simply read all this. I was planning this project for a full year before I even got the car. Any help I get is help keeping the dream alive and well.

 

ttt

 

No details about the delay circuit in my '79 service manual so I can't help much with operational details.

'80 may be different but for '79 the WIPER fuse in the box should NOT be present! An inline fuse to the delay controller provides the circuit protection. Delay operation cannot occur with the fuse in the box because the wiper will have constant +12V power available via the white wire at the motor connector. With the delay system installed and working the white at the connector should be DEAD with the wiper switch at "OFF". The yellow wiring coming from the controller should go hot (+12V) with the wiper switch at any* operating position. *Power at the yellow wire stops during the actual delay in the delay mode.

The next thing I would check is to see that the delay pot changes resistance with the switch in the "DELAY:" position. The switch I bought from ZIP a couple years ago changes resistance in every switch position except delay! Obviously that prevented delay from ever working

I managed to repair my original switch and found that the delay still didn't work. Why? The wiper blades were old and the arms skipped/chattered across the windshield. The skipping motion prevented the delay from "catching".for the near instant when the arm in the wiper motor opens the contacts in the wiper cover.

I do not know how to test the pink wire leading from the wiper cover. As best as I can tell from the schematics it has positive electrical potential (+12V through a latching relay coil that momentarily grounded during "WASH") whenever the wiper motor has power from the yellow wire leading from the control module except for the moment when that contact in the wiper cover opens. The controller (via very high resistance to ground?) then "catches" that moment of lost potential and stops power to the motor via the yellow wire as long as the switch in the cover stays open during the delay period dictated by the delay rheostat.

 

Go to my tech page... if you have a new switch odd's are it's the issue but there is info on how to test it to see. I've also posted all the info for your car here so use the advance search and you should be able to find all the info on your car. If it were my car or one in my shop, I'd rebuild the original switch... there are instructions on this as well.

http://repairs.willcoxcorvette.com/?yt=1979&s=wiper

 

Mike- Thanks for the info!

I'll double check the fuse. The delay slowly morphed into low speed, used to work fine. But I may have seen a missing fuse and popped it in.
The delay pot does change resistance in delay, but it's super high. Like 400k to 700k iirc. Both switches are like that. Any idea what the range should be? Shorting out the pins (zero resistance) does not cause it to delay.
Wipers chattering, that's crazy. Good find.
Thanks for digging into the schematics. So if I understand you right, there should be 12V coming out of the pink cover wire from the motor? Hmmm, I wonder why I have voltage coming from the module side... Something to check into there. There is some kind of a signal change as the motor spins around, but it's weak. I'm gonna talk to my parts guy today, see if he can dig up another motor for me to try. No "known good's" available, unfortunately.

Wilcox- That is awesome. All the digging I did on Google, and that never came up. From one of the pics, it looks like the arm on the back of my wiper motor cover is missing the end of the tab. Hopefully I can repair that.

Thanks again guys.

 

That arm is attached to a resistor which tells the module the location of the arms.

Did you find the one on how to rebuild the original switch... it's pretty easy.

http://repairs.willcoxcorvette.com/w...tch-repair.pdf

And while you have the switch open it's always smart to clean the potentiometer.



Willcox

 

Sorry but I can't remember the resistance range of the delay pot when I tested it.

According to my '79 schematic that pink wire coming from the wiper cover leads to the ground side of a relay coil that operates a ratchet that serves to keep the wipers running for a few strokes with a momentary push of the "WASH" button. That same wire is spliced to the pink wire that provides ground to the washer pump. The schematic does not show the switch/carbon resistor in the wiper cover and the circuit description gives zero details regarding the operation of the delay module. It is though apparent from the schematic that the brown wire at the module is the +12V feed with inline fuse with the yellow wire from the module providing the only source of +12V to both the wiper motor and washer via their white wires (the wire color changes at C529 whose location is not specified. All* of the other connections to the delay module are ground inputs, ground outputs or the delay pot inputs. *the pink "control" wire at the delay module [appears] to be a hybrid that provides both input (via the switch/carbon resistor in the wiper motor cover) and ground output (to the washer motor and ratchet relay coil in the motor unit). It's obviously a very clever circuit with the unexplained operation of the pink wire the key to operation.

 

Sorry about my absence, not trying to leave you hanging. Have some other projects I need to keep up with. Thanks again for all the info.

One of Wilcox's pictures shows the inside of the wiper motor cover. The arm in there is of particular interest to me; the contact at the very end of the arm is broken. I can't find a cover available anywhere, so I'm going to see if I can find time to repair it. I will update with results and pictures.