K2599 wiper delay wiring with 2 speed GM motor


I need some help on wiring my GM 2 speed wiper motor.

it works by grounding one or two wires:

  1. no grounds = OFF
  2. both grounded = low speed
  3. just HIGH grounded = high speed

so how do I wire this into my car?

I was thinking about connecting a ground wire to the A and D on the schematic.
And then connecting the B and F parallel to LOW and HIGH connection of my GM motor.
this way the original wiring stays functional and when the Velleman module closes both relays it ground both LOW and HIGH to ground and thus activating the LOW speed of the GM motor.


As far as we can see this should work.

I installed it this way and it works fine.

just wanted to confirm that for other users in future.

but have a another question:

when the car idles or drives very slowly the circuit switches to quick, causing the wiper to stop in the middle of window. also the delay time will be irregular.

a friend with the same car (Chevrolet Suburban) has the same problem.

I have it wired from the IGN (switched power supply) and he has it powered from the wiperwashermotor +12V connection.

something is causing interference I guess messing up the delay.

Any ideas what might be causing it?

I waas thinking in the direction of the HEI ignition. during idle and slow speed the mixture is lean, causing high resistance in the ignition system and thus more intereference??? and this could mess up the IC555?

Adding a large cap (e.g. 4700µF/25V) across the power supply terminals of the kit can help.
Mind the polarity.

Thank you. Biggest I currently have is a 100 or 1000 uf capaitor. Would that work?

It cannot hurt to give it a try with 1000µF :slight_smile:

I installed a 22uF yesterday and for now that seems to have solved it. I’ll report back here if it stays like that.

Strange that 22µF would do the job.
This is like adding a drop of water to cool a cup of coffee…

as promised I am reporting back on how everything works out.

we had a very rainy knight and I drive the car for over an our in total. The circuit had not one hickup. So the rather small 22 uF capacitor seems to do the job.

Hope this helps other people.

thanks for the help.

Thanks for the info.
Most likely, the problem is caused by HF interference, that might explain why a small cap does the job.

your welcome, hope it helps other people. thanks for the quick support.

Well…I am back again…problem wasnt solved completely. yesterday on a warm day the cooling fans turned on. And you guessed it, the circuit went crazy, ratteling like a rettle-snake.

I guess the fans make too much noise for the circuit. I am gonna dig up that bigger capacitor and see if it solves is.

Ill report back whn I know more.