Electrical gurus; help me rig a neutral safety switch
 

I have a Wilwood clutch/mc pedal assembly routed to a Tilton Hyrdraulic TO. Car is a Classic Roadster and probably has the wiring set up to do it - I will check. How can I rig a mechanism to trigger. Thanks

The tremec has a neutral safety switch built in. Use it as a trigger to control an interrupt relay on the start circuit of the ign key.

Mr. Fixit, thanks for the response. However, it went way over my head. Speak to me like I am an electrical Idiot please. I dont know where to begin "interrupt relay"?? So the tranny has to be in Neutral or the starter wont work? I have the Tremec manual. Are there instructions in there?

Basically he means to use the built in switch on the tranny and you use it to interupt the wire on your ignition switch that engages the starter. You want to use a relay so it protects the ignition circuit.

I'm sure someone around here probably has a wiring diagram for that.

Scott

There is a wire to either the starter, or starter solinoid. You will want to interrupt that wire and have it go to a relay controlled by the transmission and then to the starter/solinoid ( no taking off for spelling ).

When the transmission is in neutral, the relay closes and allows current to flow to the starter/solinoid. If the trans is in any other position, the relay will not close and the starter can not be engaged.

You want to use a relay for two big reasons; service and protection.

Hope this helps.

Trularin

Curt..Bet ya still confused...:rolleyes:
See if I can make it easier.
On the back of your ignition switch you will find a number of wires..find the one that goes to the S (start) terminal on your starter solenoid. It will be a heavy (12Gauge maybe) wire.

This wire needs to be disconnected from the S (start) terminal on the solenoid and connected to the neutral switch on your Trans. From the other terminal of the neutral switch on the trans, connect a wire (same size as the before mentioned wire) and route this wire and connect to the same terminal ( the start (S) terminal) on the starter solenoid, from where you removed the original wire.

What happens is this: If you are in neutral, the switch on the trans allows power to be passed to the starter..thereby starting the engine. If you're in gear, it wont allow power thru, thereby preventing the engine from starting whilst in a gear and running over ya dog.

When the fellas talk about a relay or a solenoid...they are referring to an electrical switch which is activated by power (as opposed to a switch you manually turn on). Relays and solenoids are used to switch large current draw components(starters, horns, fans etc), which use a current which would fry a normal switch. There is of course a manual switch which activates the solenoid/relay (ignition for example) but only needs to conduct relatively low power to switch the solenoid/relay which in turn switches the heavy draw component.

Whew!.....hope that helped

Les

Curt, hope this upload works...see the attached photo for a very crude wiring diagram.
The easiest way would be to take the wire that now energizes the starter solenoid off the solenoid, hook it up to a power and a trigger terminal on the solenoid, run a wire from the other power terminal back to the solenoid and run a wire from the other trigger terminal to the trans neutral switch. If it is a 2-wire switch at the trans, run the other terminal to a ground.
It works like this: When you switch to the start position, power from the switch goes through the relay trigger circuit, to the trans switch and (if the trans is in neutral) to ground, energizing the trigger and closing the relay. At that point, power goes through the power circuit on the relay and on to the starter solenoid and cranks the engine. If the trans is not in neutral, the trigger circuit is never energized and power never gets to the solenoid...

Perfect, the explanations and diagram are exactly what I needed. One last question. What kind of relay (description) and where can I find it? Hehe, this is much simpler than I previously thought.

Radio Shack has an inexpensive one, all black plastic housing (a little chintzy), but it is rated @ 30 amps, should be sufficient. It has a mini-diagram on the package and on the body of the relay. Just make sure you get one designed and rated for 12 volts.

OK I got the switch Mr0077 described. It has four posts: 12V in; 12V out; 12V switch on/off; and a ground. Let's see what I have learned: The wire from the solenoid previously going to the starter goes to 12V in; 12V out goes to the starter; 12V switch on/off goes to the tranny switch and ground goes to ground. Is this correct? Also, I still have to ground the other side of the tranny switch?? Per the diagram on the relay package, the 12V in crosses the 12V switch on/off. The break (relay?) occurs after this intersection going to 12V out. You know, I have assembled 2 engines starting with short blocks, tuned carbs, set up blown EFI combos, but I am simply ignorant on electrical. They don't teach this important stuff in B. School or the car mags for that matter. I do enjoy learning and self teaching though. Thanks guys.

Curt, your description was right, except where you hook up the transmission. Refer to the photo, and you'll see that the same 12V going to the contact terminal should also go to the trigger terminal (more on that in a second). The other side of the trigger terminal goes to the transmission. If it is a one-wire trans switch it grounds internally...if it is a 2-wire trans switch, the second wire should be grounded to the frame, trans case, etc. With this wiring layout, you use the starter wire to energize the relay.
An alternate way to wire the relay is to have a 12V (FUSED!) wire going to the 12V "in" terminal and the ignition starter wire going straight to a trigger terminal, so all the starter voltage would do is trigger the relay, and the 12V in would energize the starter. The 12V out still would go to the starter solenoid terminal and the other trigger terminal would still go to the transmission...did that make any sense at all?
And also, I am assuming that what they call 12V in and out are shown as passing through the contacts on their diagram (theirs should be similar to mine in the photo). Good luck!

Yes, Yes, I see. I somehow got it in my head that there were 3 terminal in your drawing. Yes, the diagram on the package is just like yours except the lines are perpendicular. I thought something was wrong with my description because it contained two grounds. One last question. The existing wire running from the SN to the starter is quite large, approx 1/8 inch. Will 12 GA be enough to energize the starter or should I go larger?

Curt, I guess I got a little myopic and didn't ask...does your starter have a solenoid mounted on it? Do you have a firewall mounted solenoid? If you have either one, does the 1/8" wire you're talking about (from the SN) run from the ignition switch to the solenoid, or from a firewall-mounted solenoid to the starter? If from the ignition switch, the relay and 12 GA wire should work; if that big wire comes from a solenoid or somewhere else, you will want to insert the new relay in line with thestarter wire that runs from the ignition switch to the solenoid (or relay)...that should be a smaller wire, maybe 12 GA or so. That size wire (1/8") makes me think it is coming from a solenoid, not the ignition switch (usually switch wiring is smaller, 12 Ga or so).

Yup, its coming directly from the firewall mounted SN (solenoid) to the starter. I will look for a wire going to the SN from the ignition and report back.

Curt

Nuetral? as in? www.switzerland.com

SCOBRA, good one! Yeah, I guess we need a neutral switch...that is, a switch that lets the neutral countries to see things our way...hahahahahaha...thread entropy.

Not sure it needs to be this complicated. On a CR, wire #121 runs from the ignition start to the starter safety switch on the trans. Wire #126 runs from the trans neutral safety switch to the starter solenoid.

Plug the trans wiring harness into the trans neutral safety switch and backup light switch, and you're done.

That being said, CR also had to accommodate those using automatic trans's. You may have to locate the AT 121 - 126 connection and jumper it.

WOW!
I had no idea this was about a CR's harness and a neutral switch!
Like Jack says, IT'S ALREADY IN THERE!

Find the small grey plug plug coming off the steering column harness with only two wires - 126/121. Extend these wires to the neutral safety switch on the transmission and your done!

Don't know which plug on the transmission is the neutral safety switch? Buy a cheap dwell meter with an audible tone for continuity. Touch the probes to the two brass pins on the tranny, with the tranny in neutral. Nothing should happen, put the tranny in gear and you will hear the tone.

That simple :D

DV...Plug it in and bring that baby to the Fling!

The same wires come off the engine harness under the hood. There is a 4 wire plug with wires 121, 126, and the other 2 are for the backup lights. Classic should have supplied an extension for these wires that reach the trans. Somewhere along the line someone must have put a jumper on wire 121 and 126 otherwise the car would not start.
Don

You guys saw me coming. This morning I got out the CR manual in an attempt to verify the starter wire. There they were 121 & 126 starter power and starter control. Don has to be right. Somewhere in the system 126 and 121 are combined right? Anyone familliar with the Tremec. There are two electrical connectors: one in the rear with a pigtail coming off it and one in the middle of the trans with male connectors. Which is the neutral safety switch? My Tremec manual does not identify either.