Dr3 + prs7 = pita

[Ivygreen65]

I have finally gotten to the point of installing my Lucas DR3 wiper motor and PRS7 wiper switch. I bench tested the DR3 and both speeds worked well. I checked continuity on all the switch terminals and positions and it checks out. Checked continuity between the switch terminals and the wiring connections at the DR3 and all is well. I do have 12V to the green power wire at the wiper motor. However, I cannot get the motor to work from the switch.

Total disclosure - I did reverse the blue and the red armature wires in the DR3 to get the motor to park on the passenger side. However, I have bench tested the motor on the kitchen counter and on the car and it has worked both times. I'm basing the wiring off of the common DR3 & PRS7 wiring diagram. I'm guessing I am missing some very simple detail and will be feeling really stupid when I get this figured out. Any thoughts or ideas will be greatly appreciated.

[Mongoose930]

I had some issues with this as well and I kept the documentation on how I did it. If you want to PM me your email address, I will go through my records, pull my notes, and send them to you.

[Mongoose930]

Picture of my battery-driven test fixture. I used a fuse block that had both positive and ground connections.
Attachment 39497

[Tommy]

I can only offer these generic observations about wipers that may or may not apply to your particular car. First, in order for the park function to work, the motor must have access to both power and ground even when the switch is off. So in general the motor must have access to ground both where it is mounted and through the switch. Second, if the motor is mounted to a fiberglass panel, it will not be grounded unless it is connected to a ground via a wire. Good luck.

[Ivygreen65]

This video shows the process that I went through to bench test the DR3 both on and off the car. The motor works when I have bench tested.

https://www.youtube.com/watch?v=jSfJWNBE2-Q

With regards to a ground, I was under the assumption that the ground in the switch was the proper ground for the circuit. However, I'll try to ground the motor and see what happens.

[Mongoose930]

I scanned the two documents that I used to wire my wiper switch and motor. Unfortunately, they are too large to attach. I am happy to email them to you if you PM me your address. These are both from original Cobra experts so they should work for you.

[Ivygreen65]

Originally Posted by Mongoose930

I scanned the two documents that I used to wire my wiper switch and motor. Unfortunately, they are too large to attach. I am happy to email them to you if you PM me your address. These are both from original Cobra experts so they should work for you.

I PM'd you yesterday, but I don't see a copy in my Sent folder. I'm sending my email address again.

[Ivygreen65]

Thanks to Tommy and Mongoose for putting me on a potential course to a working wiper motor. Tommy mentioned grounding the motor and Mongoose sent me a drawing that notes grounding the motor. Grounded the motor and I now have Park and High speed. I'm guessing not having Normal speed is due to a connection issue, but I'll work on chasing that down. Thank you guys.

[Tommy]

On the system I'm familiar with (not yours), there are two wires from the switch to the motor that control the speed. As best I recall grounding one wire at the switch yields slow speed and grounding both wires at the switch yields high speed. You may want to try some of those combinations to see what you get.

[Ivygreen65]

I have a second (but crustier and rustier) PRS7 switch, so for sh!ts and giggles, I hooked it up. Got Park, Normal, and High. So, I took my good switch, loosened the nut on the back, and cycled it through all positions about 100 times trying to scrape and hopefully clean the contacts inside. Fixed the issue and now I have a wiper system that works 100%. Thanks again to all for the help.

[PDUB]

Caigs Deoxit will clean those contact up nicely. You can get it over the counter at Guitar Center... works magic on electrical contacts! Get the basic version.