Neutral safety switch questions.

[P Dubya]

1969 Road Runner. Has been flawless all summer long until last Sunday. Shut it off at a local convenience store to get a bottle of water. When I came back out I had a no crank/no start issue. Played with the shifter (column mounted A/T) thinking maybe the N/Safety switch could be the culprit. Same issue in any shifter position. With key in 'run' position engine started immediately when jumped across firewall mounted relay. I was happy to make it home but have had no time to diagnose where the problem is. Am I correct in thinking the N/Safety switch is my most likely area of investigation? Is there anything that happens in the key switch that activates the N/safety switch prior to cranking?

 

[R413]

Could be NSS.

But first have a helper inside the car holding the key to start position while you wiggle the wires and plugs at bulkhead and starter relay and see if it starts. Then you will know which wire are at fault.

If you wiggle them then get in car and it starts which wire was it?

 

[Black_Sheep]

On an automatic trans car the starter relay grounds through the center pin of the neutral safety switch on the trans. If checking the connections doesn't reveal anything I would check for continuity to ground at the neutral safety switch using a multimeter. If there's no continuity it's your NSS. If there's continuity to ground at the NSS, check the wiring from the ground terminal on the starter relay to the center terminal of the plug that goes on the neutral safety switch. I went through this on my GTX last winter, the wiring appeared okay on the outside but flexing it near the plug at the trans caused the circuit to come and go, there was an internal break. Instead of splicing in a new plug I opted for a complete NSS/back up light harness for the sake of reliability. It was around $42...

 

[P Dubya]

With a little testing I'm fairly certain my problem is in the NSS. Yellow wire sends signal from ignition switch to relay but I get no ground from from NSS. When I unplug wire from NSS and use a jumper to ground the engine cranks right over...

 

[dadsbee]

Pull the plug off the switch, jump the center socket to ground. If it starts, check the center lug on the switch to ground for continuity in Park / Neutral. Do you currently have reverse lights???? If not, possible it's that not the switch and instead the roster comb fell apart inside the trans..

 

[P Dubya]

Crawled under car and found wiring harness to not even be attached anymore to switch. It's in pretty rough shape so I pulled the entire boot and harness up to the engine bay. Is there a reputable replacement for this boot and harness? It's only 3 wires and I would be fine building my own if I can get a new boot, this one is quite cracked...

 

[Black_Sheep]

You can get a molded plug with blunt cut wires. As I mentioned in my previous post, you can buy the a reproduction harness for around 40 bucks.

 

[GTXDAN]

You can get just the plug with pigtails at Rock Auto.

 

[P Dubya]

You can get a molded plug with blunt cut wires. As I mentioned in my previous post, you can buy the a reproduction harness for around 40 bucks.

I found both the repair end only and the complete harness. Classic industries I think... About $65 for a complete harness so I will likely go that route. Thanks!

 

[P Dubya]

This is my simple 'get me by' fix until I can get a new harness...

 

[Black_Sheep]

I found both the repair end only and the complete harness. Classic industries I think... About $65 for a complete harness so I will likely go that route. Thanks!

Wow, the price went up 50% since last winter…

 

[Nacho-RT74]

Considering the NSS harness is, along with engine harness, the easier to get damaged with heat and oil, and considering the price difference, the full harness is a best investment than just the pigtail, which results on get soldered to an very bad aged harness.