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I think I have read every old post regarding the Russ Thompson turn signals with Ron Francis harness but I still don't understand why there is so much duplication and extra wiring. I got my MK4 complete kit back in March and I am just starting to dig into the wiring. The Ron Francis wiring diagram and harness seems quite complete with labeled wires, relays, flasher,etc. . The RF wiring diagram shows three wires plugged into the supplies three position toggle switch for the turn signals. If I plan to use the Russ Thompson 3 wire turn signals, why can't I just replace the 3 wire toggle switch with the with the RT unit? The other two red wires on the RT unit that come from the stem button I plan to use for the horn. I spoke to Russ today about this and thinks it should work. The high/low beam and flasher toggle functions would stay as originally supplied. Has anyone tried this??
 

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I am doing the same.

The extra relays and such is to be able to use the button as a high and low beam switch
 

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I think I have read every old post regarding the Russ Thompson turn signals with Ron Francis harness but I still don't understand why there is so much duplication and extra wiring. I got my MK4 complete kit back in March and I am just starting to dig into the wiring. The Ron Francis wiring diagram and harness seems quite complete with labeled wires, relays, flasher,etc. . The RF wiring diagram shows three wires plugged into the supplies three position toggle switch for the turn signals. If I plan to use the Russ Thompson 3 wire turn signals, why can't I just replace the 3 wire toggle switch with the with the RT unit? The other two red wires on the RT unit that come from the stem button I plan to use for the horn. I spoke to Russ today about this and thinks it should work. The high/low beam and flasher toggle functions would stay as originally supplied. Has anyone tried this??
You can do this but you will need to install a relay between the horn and Russ's button as it isn't designed to handle the current draw of the horn. The rest of the wiring is pretty basic UNLESS you want to have Left/Right turn signal lights in which case you need diode's to isolate the circuits from the flasher circuit.

HTH
Todd
 

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Jim,
You are correct and that is the way I did it. No diodes for the turn signal indicator lights (I did a left and a right light). I pretty much followed the wiring diagram that came with the RF harness and it has worked out for me.
As for the horn, I just wired it direct without an additional relay.
 

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Jim,
You are correct and that is the way I did it. No diodes for the turn signal indicator lights (I did a left and a right light). I pretty much followed the wiring diagram that came with the RF harness and it has worked out for me.
As for the horn, I just wired it direct without an additional relay.
You should really consider installing a relay for the horn. The FFR wiring harness places a 15A fuse in the horn circuit but the horns can draw over 10A. The challenge is that the rating on a small microswitch like the one Russ uses is typically between 5A and 10A. Unless Russ installed a heavy duty switch (not sure he has room with his design) it will work for a while but if you hold it down for too long you run the risk of blowing the switch. When it blows you will have one of two modes: 1) it may not turn off or 2) it may never work again. Both kinda suck. A relay costs less than $5 and is easy to install even in a finished car. Happy to post a schematic for you if you are interested.


HTH
Todd
 

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You should really consider installing a relay for the horn. The FFR wiring harness places a 15A fuse in the horn circuit but the horns can draw over 10A. The challenge is that the rating on a small microswitch like the one Russ uses is typically between 5A and 10A. Unless Russ installed a heavy duty switch (not sure he has room with his design) it will work for a while but if you hold it down for too long you run the risk of blowing the switch. When it blows you will have one of two modes: 1) it may not turn off or 2) it may never work again. Both kinda suck. A relay costs less than $5 and is easy to install even in a finished car. Happy to post a schematic for you if you are interested.


HTH
Todd
I am no electrical guy, but according to the RF wiring there is already a horn relay between the switch and the horn, so I just assumed that would be able to control the current going through the dash switch, so it would protect it. That was how I looked at it. I guess you could swap the fuse to a 5 or 10A and give more protection for the smaller switch, right?
 

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I am no electrical guy, but according to the RF wiring there is already a horn relay between the switch and the horn, so I just assumed that would be able to control the current going through the dash switch, so it would protect it. That was how I looked at it. I guess you could swap the fuse to a 5 or 10A and give more protection for the smaller switch, right?
My bad. You are correct. The Ron Francis wiring harness includes a horn relay so you don't need to add an extra.

Apologies for the confusion.

Todd
 

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All great information
 

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Wow. something just got easier. Great info...

.....gotta give Russ a call and order mine plus gas pedal.
I just installed Russ' gas pedal last night. It is very nice, and you can easily adjust it to get the perfect heIght . Minor tuning to get the cable well aligned with the housing.
 

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scrap the F5R switches, i can't believe RF didn't just tell you that you need these,
page 62 of catalogue, i used the S-11 and the FW-24. F5R should just supply these in the RF harness set-up and it will make life so much simple for those that use the turn signal switch, the 2 switches are needed to work together.

oh and the diode wiring that is only for if you use one light for both lft. and rt. signal

you can up-grade again and go to the self cancelling part # ss-25 and the clamp on turn signal SS-7

good luck and happy wiring don't get toooo wired out:001_tongue:
 
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