Won't crank in Park but will in nuetral

[MOrePowAR]

Purchased a 72 Swinger was a 6, put in a 383/727, put all the wiring back in the engine bay. checked the NSS in the trans. I get a reading in Park & Neutral when I try to crank in park the seat belt light dims but won't crank, if I go to Neutral the seat belt light goes out and it cranks. Shifting the lever from Neutral to Drive with the key on, a relay under the glove compartment will click, what does this relay control? There's no butchered wires in this car. Thanks if anyone can help

 

[moparlvr166]

I don't think the seat belt warning system will cause a no crank (only warning sound and light), 1st thing i would do is make sure shift linkage is adjusted correctly, next make sure you have a solid ground from engine to body.

 

[Johnny Mac]

I vaguely remember a similar issue after my v8 swap. I believe I rotated the NSS plug 180 degrees and the issue went away. Does the NSS appear the same as the one in the 904 you pulled out? also check your reverse lights, make sure they are working properly. those should be on that same switch. I remember mine sticking on in all forward gears if i had the switch plugged in wrong.

no idea what relay under the glove box you are hearing...the starter relay is on the driver side in mine..?

 

[Johnny Mac]

I don't think the seat belt warning system will cause a no crank (only warning sound and light), 1st thing i would do is make sure shift linkage is adjusted correctly, next make sure you have a solid ground from engine to body.

I know on my 74 if the floor/seat harness was plugged in, the engine wouldn't crank at all unless the seatbelt was hooked in. I didn't think this was on cars until 74 thought. But anyways, if he has plugs going to his seats and seat belts, simply unplug them to kill the safety feature.

 

[TrailBeast]

You might want to look into the seatbelt interlock, and take it out or bypass it if your car has one.
You can find this info here with a search.
They can do this due to a bad switch on the trans also.

I NEVER EVER leave my car in gear, when I park and I always take a glance to make sure it's in park before I hit the key, so I wouldn't hesitate to remove the safety switch from the starting system completely on my own car if I had a problem with it.

Besides, it's nice if the car stalls for some reason then you can just hit the key again without having to get it in neutral rolling, or stop to use park to restart.

The specific problem you are having does sound like the switch on the trans though, (IF you have a column shifted trans)
Consol shifted sometimes uses a switch on the shifter mechanism, and they can also work in one position and not the other due to adjustment issue's.

There is no adjustment that will help if the switch is in the side of the trans, as it relies on the linkage inside the trans to determine whether it is in park, neutral or other.
It's pretty much always a bad switch on those if it works for one or the other but not both park and neutral.(unless someone mixed and matched parts inside the trans)

 

[MOrePowAR]

thanks for the input, will check ground to body, connected seat belt same issue, don't have the 904 as the V8 was in but nothing hooked up, sitting on 2X4 for mounts and an RV trans that wouldn't work, that relay has me baffled though

 

[AJ/FormS]

What year is the tranny? Seems to me the early trannys had a 2 pole nss, and the later ones had a 3pole. The change-over year was around IDK; maybe 73?

 

[RedFish]

I've seen several cases where the steering column was dropped for inst' panel repair and the condition you have was result. reach over column with left hand and pull upward hard on it shift lever and see if it starts. Proper procedure for adjusting shift linkage is in service manuals. Park is a fairly tight position in movement. Neutral is wide open since the shifter travels through it north and southbound. There aint much north of park.

 

[ktcnn94]

MOrePowAR, not to change the subject on you but how bout some details and pics of that engine swap, sounds interesting.

 

[d55dave]

68 and prior had a single pole nss that only did neutral safety. 69 and later have a three pole switch that does neutral safety and back up lights. The internal part that activates the switch also changed so you cannot just replace the switch between styles.

68 and earlier cars had a separate back up light switch inside the car on the shifter.

 

[AJ/FormS]

Yeh, thats it 68/69.
Sorry. Sometimes Im no help at all.

 

[d55dave]

No problem. We all try! Perhaps there is a mismatch of parts here, the wrong switch in the transmission?

 

[MOrePowAR]

Putting a big block is not as easy as they say, don't believe the mags. Things you need to know. Welding, fabricating, cutting lots of patience and no when to walk away when things aren't going right, but having fun drinking a lot of beer

 

[alpha13]

The only reason I didn't go big block is because I couldn't see myself cutting up perfectly good inner fenders for the headers.

 

[harrisonm]

Doesn't anybody make headers for big block A-Bodies???

 

[oldkimmer]

Doesn't anybody make headers for big block A-Bodies???

..................TTI Tube Technologies Inc....................kim........

 

[halifaxhops]

Schumacher also makes them.

 

[alpha13]

I'm gonna do the 408 stroker. I'll look into the Schumacher and tti. I might need the info one day.