TKO conversion - back up switch and neutral start hacks

[smh00n 87]

Ladies and Gentlemen

I am into the wiring for my TKO conversion from an auto, and just needed some hand-holding before I chop wires up. The car has been hacked up especially in the back so I don't want to spend nights pulling wires and hair out.

From this thread I see I am looking for a black and red wire into a 4 wire connector (labelled "H") at the firewall to plug the back up switch from the trans into. Yes? I guess there is power into this switch from the 296 wire out of the fuse box? So I need to make sure 12V is on one side?

And then, in back I have the same single red/black wire to power the reverse lights. Yes?

Next, I have seen you basically jump the original neutral start wiring to bypass the original automatic gearlever switch. Can someone give me wire colours to jump? I have a single wire and also a block of about 4 that came off the auto.

Last, can you buy the OEM moulded plugs? I have LED lights for the hood turn signals, but they have been hacked before from the harness plug, so I was going to make a new harness; but I don't have any of the original plugs used. I can use dodgy connectors but prefer not to.

 

[Midlife 814]

NSS wire colors are red/blue.

Most Ford molded connectors are standard trailer connectors.  You can find many of them with pigtails (but not with the correct Ford wire colors) at https://www.delcity.net/store/Molded-Connectors-without-a-Loop/p_8593

[smh00n 87]

12 minutes ago, Midlife said:

NSS wire colors are red/blue.

Most Ford molded connectors are standard trailer connectors.  You can find many of them with pigtails (but not with the correct Ford wire colors) at https://www.delcity.net/store/Molded-Connectors-without-a-Loop/p_8593

Thanks - they are in the same plug by the looks of it?

I looked again the the hood turn signals. They have cut the original wiring...

I have  a couple of single connectors near the 4 way NSS/reverse plug. One has gray wire. One I remember went to the auto shifter. Is that just a light power switch? 

[Midlife 814]

Grey is probably the carb anti-stall wire.  You can ignore that.  The PRNDL wire is brown or blue/red.  And yes, the BU and NSS wires are all in the same plug.

[Rich Ackermann 174]

I am jumping in to the middle of this thread, so just ignore it if this is not helpful....

You can permanently or temporarily bypass the NSS by connecting the two Red- Blue Stripe wires together in the four pin plug coming from the firewall. It the same as the loop-back Ford used on manual cars. I bought the manual safety switch wire harness for my Tremec. It had the correct factory 4 pin plug on the one end and the tremec plug on the other.

 

 

[Rich Ackermann 174]

On 3/5/2023 at 9:52 PM, smh00n said:

Ladies and Gentlemen

I am into the wiring for my TKO conversion from an auto, and just needed some hand-holding before I chop wires up. The car has been hacked up especially in the back so I don't want to spend nights pulling wires and hair out.

From this thread I see I am looking for a black and red wire into a 4 wire connector (labelled "H") at the firewall to plug the back up switch from the trans into. Yes? I guess there is power into this switch from the 296 wire out of the fuse box? So I need to make sure 12V is on one side?

And then, in back I have the same single red/black wire to power the reverse lights. Yes?

Next, I have seen you basically jump the original neutral start wiring to bypass the original automatic gearlever switch. Can someone give me wire colours to jump? I have a single wire and also a block of about 4 that came off the auto.

Last, can you buy the OEM moulded plugs? I have LED lights for the hood turn signals, but they have been hacked before from the harness plug, so I was going to make a new harness; but I don't have any of the original plugs used. I can use dodgy connectors but prefer not to.

 

Here is the way I wired the NNS and Backup Lights Switch on my factory 1070 Mach 1. Manual 3 and 4 Speed cars had basically the same NSS/Backup Light harness out thru the firewall  to the four pin plug. Automatics had the NNS safety switch harness to the trans, whereas manual shift cars had a loop back wire in the plug on the trans side. If you wan the NSS to function with your Tremec TKO, then you will need The Tremec NSS harness, and the Tremec to Ford Backup Light harness, (Scott Drake has a nice one). Also some 14 AWG wire ( blank ground wire) and a 4 or 5 terminal 12v 30 amp Relay and some blade connectors or matching relay plug (a mounting bracket optional). The relay is  needed because the NSS will trip the relay on or off when it completes or disconnects the  the ground circuit, which in turn will connect or disconnect voltage to the starter solenoid. I read that you should not pass 12v thru the Tremec NSS, if you do it will eventually stop working. 

Fish one or two ground wires  thru the Tremec to Ford Backup Light harness (only need to fish one wire thru the harness if you ground the second wire in the harness to the undercarriage near the Tremac). I brought both ground wires to the the firewall. One near the four pin plug and the other I grounded to the firewall with the wiper ground wire. One NSS ground wire goes to relay terminal 30 and the other as mentioned before to the chassis ground. If the Backup Light harness four pin plug has the red/blue striped loopback wire cut the loop wire in half so yo have equal wire lengths. Identify which of the two Red/Blue striped wires that you just cut is coming from the ignition key/switch side and mark it as such and connect it to the 30 terminal on the relay. Make a 3 inch pigtail wire when crimping the relay terminal spade to the end of this Red/Blue striped wire and connect the pigtail to the relay's 86 terminal. Finally, connect the other Red/Blue striped wire you cut to terminal 87.  Here is a diagram of what I just described...

And a Video explanation... 

https://www.google.com/search?q=tremec+nss+operating+instructions&rlz=1C1RNOE_enUS743US744&sxsrf=AJOqlzWMKee-Og6jW4d4Lx6FuN1Jjrw-TA%3A1679098093900&ei=7QAVZNfMNrOpptQP7Ye_iA4&oq=tremec+nss+oper&gs_lcp=Cgxnd3Mtd2l6LXNlcnAQARgAMgUIIRCgATIFCCEQoAEyBQghEKABOgoIABBHENYEELADOgUIIRCrAkoECEEYAFCED1jrMGDoSmgBcAF4AIABtgGIAcADkgEDMi4ymAEAoAEByAEIwAEB&sclient=gws-wiz-serp#fpstate=ive&vld=cid:50bbc5eb,vid:lJ8B6Iim_F4

 

[smh00n 87]

Phew. Super mind-bending day at work and just read this. I appreciate it, have not thought about keeping the NSS active but probably not a bad idea. The video is simples, nice easy bit of work.

I'll digest it later when my brain is not telling to go to the fridge and take 3 beers in quick succession (like a Doctor says take some pills and call me later, beer fixes my issues)

 

[Rich Ackermann 174]

6 hours ago, smh00n said:

Phew. Super mind-bending day at work and just read this. I appreciate it, have not thought about keeping the NSS active but probably not a bad idea. The video is simples, nice easy bit of work.

I'll digest it later when my brain is not telling to go to the fridge and take 3 beers in quick succession (like a Doctor says take some pills and call me later, beer fixes my issues)

 

I am with ya... I needed 3 beers after writing that darn post. Let me know if I can clarify anything. 

The video created by American AutoWire is a bit more generic and they use their wiring kit as a reference point. I still have the original Ford wiring harnesses in the car, so I created the diagram using the Ford wiring diagram as a reference point. It helps me keep things in context, because I will surely forget what I did a month later and have to spend time retracing my steps to refresh my memory. 

[smh00n 87]

....Or, you could just buy one of these. Amazing what you find when you search 1970 Mustang back up switch harness.

This looks like it is made/supplied by Scott Drake, it is a 4 speed harness and has the correct plug. $40US is a bargain I reckon.

 

One supplier told me it had been discontinued so lucky another one had stock. The manufacture date is 2016 so it may well be obsolete.

Looks good, it has the NSS loop

[Rich Ackermann 174]

That is the one I used with my TKO, but I cut the loop and connected to the TKO's NSS harness. You can use it to by pass the NSS or use it to make the NNS work.

[smh00n 87]

Good intel. I will look at doing the NSS. Along with the fact it's a stick, that might confuse the kids who might attempt to boost it when I'm parked on the street.

[Rich Ackermann 174]

5 hours ago, smh00n said:

Good intel. I will look at doing the NSS. Along with the fact it's a stick, that might confuse the kids who might attempt to boost it when I'm parked on the street.

If you have fuel injection, you could use a second relay to cut voltage to the fuel pump while in Neutral and you are not priming the pump.

[smh00n 87]

I have Holley Sniper and it has a ground wire that I have hooked up. Engine turns over, does what it is supposed to do except fire. 

[Mach1 Driver 560]

8 hours ago, smh00n said:

I have Holley Sniper and it has a ground wire that I have hooked up. Engine turns over, does what it is supposed to do except fire. 

Just out of curiosity did you ground the white wire in the 10 pin plug to kill the engine? What ignition system are you using?

[smh00n 87]

Yes, the white wire I have connected to the cigarette lighter. Push it in, grounded. Sneaky, right? Except now the whole world knows....

I am using all MSD ignition; billet distributor, 6AL CDi box all hooked up to the Sniper. Effortless, never had an issue.

[EastYorkStang 63]

On 4/1/2023 at 6:34 PM, smh00n said:

Yes, the white wire I have connected to the cigarette lighter. Push it in, grounded. Sneaky, right? Except now the whole world knows....

I am using all MSD ignition; billet distributor, 6AL CDi box all hooked up to the Sniper. Effortless, never had an issue.

Why would you need the ground ? What purpose does it serve ?

[Mach1 Driver 560]

6 hours ago, EastYorkStang said:

Why would you need the ground ? What purpose does it serve ?

As I recall, with the white wire grounded it doesn't get an RPM signal so the EFI stays off.

[smh00n 87]

6 hours ago, Mach1 Driver said:

As I recall, with the white wire grounded it doesn't get an RPM signal so the EFI stays off.

Not sure the exact process and what it affects, but it's part of the MSD box so the engine cranks as per normal but just does not fire. The fuel pump runs, the sniper  dash lights up, all looks normal. Just an in-built kill switch.

Great idea, except when you forget you switched it and you try starting your car with everyone within a mile radius watching your every move.

[Mach1 Driver 560]

This is an alternate method of disabling an MSD box, and it comes directly from Holley:

[Mike65 475]

 GREAT info everyone, thanks for posing it since I want to hook up the backup lights & a NSS on my T-5.

[maxum96 32]

I know I'm late to the party, but I have a TKX in my 1970 and hooked up the neutral start switch and the back up light switch to my car's stock wiring.  I took the wire from a C4 neutral start switch wire harness and cut off the switch.  I bought a Tremec style back up light switch plug and the plug to mate to the TKX's neutral start switch.  I just wired them in to the C4 neutral start switch harness.  I ended up with a very clean setup that works great.  I don't have any pics of the wire harness I made, but you can see the back up light switch plug on the left side of the transmission and on the right side above the transmission mount you can see the connector for the neutral start switch.

 

 

[smh00n 87]

Closing this one out, as a job done. Although, I do question the need for a relay as when I was proving the power wires, there was only 0.240 volts coming through when the ignition was on. I don't know if that beefs up when the starter is engaged or not.

@Rich Ackermann the word description has you using 2 terminal 30. The picture is correct so the wiring sequence is

30 - power in from the OEM NSS wiring on the plug

86 -  power in from the OEM NSS wiring on the plug - I jumped these at the #30 terminal with the piggy back wire

87 - power out through the relay back to the OEM NSS wiring on the plug

85 - ground from the NSS switch

Basically all you are doing is grounding the relay with the NSS which allows power to flow through the relay and completes the circuit

(Ignore the dodgy burnt wrap, I got too excited with a butane blowtorch)

I cut the replacement 4

 speed harness wires and soldered in two new wires. I should have kept the auto loom but the guy who box the gearbox wanted it so I chopped up a brand new repro.

I got smart and put some red heatshrink on the power side, so I knew what way to wire the relay.

For the life of me I could not find out what type of connector is used on the plug, so I replaced it with a Deutsch connector. First time I used one, I'm converted. Whilst they are easier to assemble than the Delphi Weatherpack, they are dearer and the correct tool is eye watering expensive.

 

Once crimped, shrinked, tied and mounted (I hung the relay under the RH strut brace so it's somewhat hidden but easy to access), the proof was in the starting. It hasn't showed up real well but I started it in neutral and then shifted it into 1st. Cut out straight away.

Tick that job off the list :)