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1971 F250 with updated 21 circuit EZ wiring harness. The neutral safety part of the switch is working fine, but the reverse part is turning the reverse lights on when in reverse and drive. I have a new NOS switch and my original. I have done a continuity check on both to confirm that each switch is indeed completing the circuit in reverse and drive. How do I get the reverse lights to stay off in drive. I'm assuming there is something the old wiring harness that did the trick or I have two bad switches.
I'm not following something here. Your pic looks to me like you are holding the switch in "drive". And your multi meter is reading 0.00. That would mean the system is "open", AKA not connected in the switch. So the switch would not be turning the lights on in Drive.
The two red striped wires are the neutral safety switch if I recall. I've made jumpers for that plug when I put a clutch pedal in a few trucks. (or is it the other two wires?)
I can see no reason why it would read "closed" in the drive position.
How do you like that EZ Wiring harness? I just got done putting one in a plastic ****** for a fellow. Don't really care for the fact they don't mark ANY of the fuses in that little panel. You have to guess which one is which.
Yes, I was holding the switch in drive and it was completing a circuit on the reverse light wiring. Here is two images of my multi meter with the testers touching and not touching. When a circuit is completed my multi meter reads 000.0. So when the switch is in drive it completes the circuit for the reverse lights just like when it is in reverse.
The two red striped wires are the neutral safety switch if I recall. I've made jumpers for that plug when I put a clutch pedal in a few trucks. (or is it the other two wires?)
I can see no reason why it would read "closed" in the drive position.
How do you like that EZ Wiring harness? I just got done putting one in a plastic ****** for a fellow. Don't really care for the fact they don't mark ANY of the fuses in that little panel. You have to guess which one is which.
Seems unlikely to have two bad switches but maybe.
The EZ wiring harness is fine for the price, especially if you can get your hands on an orginal wiring diagram. My EZ fuse box was labeled.
I would think it is an 'AND' situation where the Neutral Safety Switch AND the Neutral Start Switch have to have continuity in the Reverse Light circuit for the reverse lights to come on. There are four wires to that switch (7A247) and I know on manual trannies in my Mustangs, the Neutral Start wires are jumpered together, and the reverse light switch is the other two wires. So if the reverse lights are on all the time, I would say the switch on the tranny is at fault.
I would think it is an 'AND' situation where the Neutral Safety Switch AND the Neutral Start Switch have to have continuity in the Reverse Light circuit for the reverse lights to come on. There are four wires to that switch (7A247) and I know on manual trannies in my Mustangs, the Neutral Start wires are jumpered together, and the reverse light switch is the other two wires. So if the reverse lights are on all the time, I would say the switch on the tranny is at fault.
Mustang NSS/backup light switch is on the side of an automatic transmission.
NSS/backup light switch on the trucks with an automatic is mounted on the steering column. No NSS/back up light switch on an auto transmission in the trucks until 1978, when they were both moved off the steering column and onto the transmission.
I would think it is an 'AND' situation where the Neutral Safety Switch AND the Neutral Start Switch have to have continuity in the Reverse Light circuit for the reverse lights to come on. There are four wires to that switch (7A247) and I know on manual trannies in my Mustangs, the Neutral Start wires are jumpered together, and the reverse light switch is the other two wires. So if the reverse lights are on all the time, I would say the switch on the tranny is at fault.
There is no switch on the transmission despite what the above linked pic shows. This same pic is in the car parts catalog, captioned: 1966/72 Ford/Fairlane/Torino/Mustang/Thunderbird.
1967/77 F100/350: The Neutral Safety Switch (C7TZ-7A247-A /Motorcraft SW-600) is located on the steering column, there is no such thing as a Neutral Start Switch.
Are you sure you haven't got the NSS and backup functions reversed? Because NSS works in two positions, park and neutral, but reverse only in R. If you're getting reverse lights in two positions that must be park and neutral. Switch backwards?
09-23-2015, 04:18 PM
have to have continuity in the Reverse Light circuit for the reverse lights to come on. There are four wires to that switch (7A247) and I know on manual trannies in my Mustangs, the Neutral Start wires are jumpered together, and the reverse light switch is the other two wires. So if the reverse lights are on all the time, I would say the switch on the tranny is at fault. 
