I'm making a switchboard for a HPDE CRX.

fuel pump
radiator fan
lights
wipers
ignition
momentary start

I'm pondering the idea of just making these all individual circuits, each with its own fuse.

The basic thought right now is to run power from the battery to two distribution blocks. From there power goes to the fuse for each accessory, fuse to switch, switch to accessory and light, light to ground. This is based off instructions I found on summit racing for the moroso switch panel. Only going to wire in the high speed for the wipers, and low beams for the headlights, so does this sound right (as in no relays)?

battery
-
distribution blocks
-
fuses
-
switches
- -
acc light
-
ground

 

This link might give you some ideas:

http://www.gt40s.com/forum/gt4....html

Relays are used for most circuits.

I also really like this concept:

http://www.racewiring.com/expanded/images4.php

 

Without relays, you'll need to use pretty heavy duty switches because you'll be running the full amperage draw of the device through the switch.

To simplify your scheme a little, I would just tie into the existing black/yellow wire coming off of your stock ignition switch for your "ignition" or "acc" or whatever you want to call it switch. That wire controls most of the critical functions (including fuel pump power) and is already fused and relayed. You can do the same with the black/white wire for the momentary start. That way you won't run the full power draw of the starter through your switch. Rad fan, lights, and wipers can all be wired directly, altho, I will warn you that if you just do a 1-wire on/off for the wipers, they will not return to their rest position when you turn them off. They will stay wherever they stopped and unless you happen to get them at the very bottom of their stroke under the hood, the air drag at speed will push them up the windshield and drive you nuts.

HTH

 

Yeah, I was looking at the wiring diagram to try to figure the wipers out.

For the momentary switch I have a 50A @ 12VDC push button. All the other switches are 30A @ 12VDC. I can get a higher rated switch if need be. I drove around town all day yesterday looking for a switch rated high in amperage @ 12VDC until I found a place that sells them. Going by the Helms, the switches I have should be rated at or over the max amperage rating for each given accessory.

 

I chose to use thermal circiut breakers.
I never want to be looking for the correct fuses on race day.
Post up some pics when you get it built.

 

very nice too much for our budgets.

Edo

 

Mine too. This is my best friend of 10 years track car that he is having me build. I'm doing the switch panel as a suprise christmas present. Pretty fair IMO for free labor.

 

Here is another beauty. http://gallo-teck.ca/speedwire/

 

About half way through right now I'm guessing. Decided to ditch the stock cabin harness.

 

if it is a HPDE car, just go stock. save your money for tires and brake pads.

 

You really should consider using relays! The switches will wear quickly with 30 amp loads being pulled through them (the contacts will be destroyed by the constant arcing with on/off movement). There are inexpensive fuse blocks that have a common input, saving you the expense of a distribution block. I made a block out of delrin in the engine bay with a post that feeds my fuse blocks, starter, engine harness, etc. From there, the power circuits branch off and head to the adjacent relay box. The switches provide ground to switch the relay on, so no fear of shorts causing a fire in the switch panel wires. I ordered all of my stuff from P-R-S (Tefzel and DR-25 shrink).

Definitely make a schematic drawing of your system. Low-side switch the relays and watch out for big power wires crossing digital signal wires such as crank angle or wheel speed sensors in your harness. There is so much to write on the subject of motorsport wiring harnesses, this doesn't even begin to scratch the surface.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tom91ita &raquo;</TD></TR><TR><TD CLASS="quote">if it is a HPDE car, just go stock. save your money for tires and brake pads.</TD></TR></TABLE>

Its my friends car. He buys that stuff. The switch panel is just a christmas gift to him since I'm already into the wiring anyways.

nfn, I drafted a schematic earlier today of all wiring in the car. The only stock items I'm using are the main fuse box and wiring for sensors/main relay, etc. Dash fuse box is gone. Using fuse blocks for all of the fuses that would have been in the dash fuse box. Wiper relay in the integrated control box is being used to they return to the off position. Decided to use the stock relays as that will be one less thing I have to worry about. All of the wiring for the engine harness is stock (only removed wiring for sensors not being used), so the stock shielding is in place. Not sure if that what you meant about crossing big power and digital signals.

 

i read "Competition Car Electrics" by Jonathan Lawes looking for advice to do what you're doing.. what a disappointment.. it's too bad because a book on this subject has so much potential to be useful
http://www.amazon.com/Competit...FWA5G

 

The way I see it, is its just a circuit. Just have to figure out the best way to make it work. When I had the cabin harness, two engine harnesses (one for using connectors from for OBD-I conversion), dash harness, and supplies (wiring, shrink wrap, solder, switches, LEDS, blah blah blah) scattered all over the kitchen floor, it looked like the great wall of China. Now with it all torn down with the schematic by me, its just a picket fence.

 

Descartes, after talking to a few other guys, apparently there can be problems with the serial cable wiring, in that the inner wires are too small of a gauge to support the system. Pretty packaging, but apparently the function is lacking a little.

 

Went back to the electronics store today and picked up some automotive relays with harnesses.

 

That depends what you consider small.....

We have some 28g mil spec wire here that well, looks like dental floss

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Stinkycheezmonky &raquo;</TD></TR><TR><TD CLASS="quote">Descartes, after talking to a few other guys, apparently there can be problems with the serial cable wiring, in that the inner wires are too small of a gauge to support the system. Pretty packaging, but apparently the function is lacking a little.</TD></TR></TABLE>

 

I'm only passing on information, I sure don't know what the hell I'm talking about myself

 

ok sorry to jack the thread but i have a question

I have my kill switch on my race car wired up, but while having a conversation with a guy who was very familiar with wiring, he mentioned that i need to run relays. The conversation got cut short and i am now left wondering what kind, how many, and were i need relays.

This is how i have my kill switch wired as it is the only true way to kill all the places that get power. The test the car must past is as fallows

1.) car is start up
2.) kill switch is turned off (car must die)
3.) tech inspector then probs with his volt meter looking for power

Question, were if anything do i need a relay?


This is my switch panel. I am drawing power from the kill switch.
question, is it ok to wire the switchs like this? Were do i need relays?


Also if there are different sized relays? what should go were? and were can i buy them?

thanks for the help!

 

Sorry to jack your question, but how do you have your wipers wired? I think I might have them figured out but I'm not sure.

Use the stock integrated control unit.
3-way switch.
On1 is for low speed
On2 is to return to the off position
Off is used after they have returned to off position

Sound right?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Aquafina &raquo;</TD></TR><TR><TD CLASS="quote">Sorry to jack your question, but how do you have your wipers wired? I think I might have them figured out but I'm not sure.

Use the stock integrated control unit.
3-way switch.
On1 is for low speed
On2 is to return to the off position
Off is used after they have returned to off position

Sound right?</TD></TR></TABLE>

I have a 3 position motor. there is Off, slow, and fast. I have them wired just like that to the switch. Off is all the way down, slow is in the middle, and fast is at the top

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Stinkycheezmonky &raquo;</TD></TR><TR><TD CLASS="quote">Descartes, after talking to a few other guys, apparently there can be problems with the serial cable wiring, in that the inner wires are too small of a gauge to support the system. Pretty packaging, but apparently the function is lacking a little.</TD></TR></TABLE>

I would think that is incorrect. For example, in a DC relay coil, the coil resistance determines the current flow through the coil. The current draw by the coil of the very popular Bosch relay is ~0.160 amps (~75 ohm coil). Even the smallest wire you might consider using in a car or RS-232 type serial cable to power the relay coils (and not the circuits) can carry 0.16 amps. A Bosch relay pulls in at 8 volts, so on a 12V circuit, you can have the wire drop 4V and it still works. Even a very small 28 gauge wire rated for 0.5 amps, for a 100 ft length has only about 13 ohms resistance http://www.epanorama.net/docum....html, so it will drop 13/(13+75)*12V = 1.77 V. You could have 200 ft of 28 gauge cable to the relay and it would still pull in. Based on this, I would say whoever told you there was a problem doesn't quite know what they are talking about.

 

Where did you get the motor and for how much? I'm going to try to make the stock motor with control box work first.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Aquafina &raquo;</TD></TR><TR><TD CLASS="quote">Where did you get the motor and for how much? I'm going to try to make the stock motor with control box work first.</TD></TR></TABLE>

It is the stock VX unit.

 

Would you mind making a quick schematic of how you wired it? Did you use the integrated control box or not?

Here is a pic of the relays I picked up, 40A @ 12VDC.
Wiring the switch into 86-85 will put power through 87-30 (pictured on left), but what does 87A do (pictured on right)?