Wiper wiring issue

[srobinsonx2]

So I have a small problem. While waiting for my engine I have been testing my electrical system. The last circuit I needed to check was the wiper which I did tonight. I am using the wiper kit supplied by FFR with the exception of the switch. I am using a simple SPDT (on-off-on) swtich from Del City and a relay per the instructions I found on this site. I have attached a sketch of my wiring.


Here is the problem. Low speed works fine. It runs and parks fine. When I turn on high the fuse immediately blows. Here is my troubleshooting so far.

1. checked my wiring and it matches the attached sketch.
2. Checked for a ground fault on the high speed wire from the switch to the motor pin #3 (white wire). All good.
3. Checked for continuity to ground on both the high and low speed pin on the motor (pins 3 and 5). Both have continuity. I don't know what this means as a ground fault on the high speed motor would also show continuity.
4. verified I do not have a connection in the switch, relay, and motor that are touching to cause a ground fault. All looks good.

I could have my wiring wrong. If so, maybe someone could point that out. I am not sure how the two speed motor works. IF it is two different motors then I could have a ground fault on the high speed motor. only and the low speed works. There could also be a wire going to ground internally to the motor. If my wiring is correct then maybe I could get some guidance on checking the motor internals. Would you recommend this?

Thoughts?

[srobinsonx2]

Forgot to say I am using a 10 A fuse. It was the size in place with the Ron Francis wiring harness.

[Boydster]

I think you basic idea is wrong. You should use relays for the slow side and the fast side. You're relaying the fast side and using just the switch for the slow side.

Also the relay wiring needs work. 30 should be constant power. 86 should be switched power (correct). 85 goes to ground (correct) and 87 goes to the load.

IOW, 30 gets heavy power, goes thru contacts and out on 87 when energized (87a when not energized). 86 gets low switched power, energizes coil, goes to ground on 85.

You've got the switch side and the output side (86 and 87) all tied together.

[srobinsonx2]

Thanks for all the advice. I did a little more research on the Lucas 2 speed motor. I am not sure if this is the exact type we have but I think this is how the two speed function works. Per the internet (which is 100% accurate :wink2, it appears that the supply of power to the slow and fast motor feeds is critical. Instead of me messing it up by trying to explain I will just supply the link to what I found.

http://www.thorden.dk/Teknik/two-speed.pdf

After reading this, it occurred to me that bobl (from the other forum) might be on to something. I decided to switch the slow and fast leads as he suggested. Both slow and fast speeds now work perfectly along with the park function. Thanks Bob.

I am not completely sure I can explain how this works but it does. I am going to continue to track this down and try to understand why but I will smile with the little win today. Here is the wiring diagram of my final set up.

[Boydster]

My bad, I didnt know about the Lucas setup. Interesting reading. Glad ya worked it out.