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Car Starting in ON Position

P

Patrick Stapler

Active Member
Just installed new engine and trans. Changed from C4 to TL. Connected the neutral safety switch connectors at the firewall together. Car starting in key ON position and won't stop unless turned off. No other wiring was changed.

Thoughts?
 
Connecting the red/blue wires by passes the neutral safety switch in the auto trans. Make sure you connect the others for the back up lights to the trans.
 
Thanks Terry. I assumed that would be the case after I discovered the red/blue wire. Not there yet however. Will try again tomorrow afternoon.

Really appreciate you taking the time today.
 
Made my jumpers this morning. Went to lunch with the family. Came back home spent thirty minutes trying to fire it off...nothing. On a whim I decide to swap the points...damn thing fired right off. Got it broke in. Shut it down.

Thanks again Terry. When you said the issue has to be at the firewall connectors, I looked closer and realized what I needed to do. I had read somewhere that you needed to short the connectors together when in reality, you have to short each connector pin to itself to complete each circuit.
 
Alright Midlife or Terry, I need some help. Same as before, I have shorted the two connectors at the firewall that previously went to the C4. Everything works except for the backup lights. I've tried connecting them together, I've tried open, I don't know what else to try. The blue/red wire comes into the reverse light switch with the ground. I've tried connecting the green wire coming into the console to the reverse switch hot side and it just blows the Dome light fuse.

I'm at a loss. I have looked at the schematics and just can't determine what I need to do to get power to the backup lights.
 
Power for the backup lights comes from the fusebox and goes down to the tranny; when in reverse, a switch relays that power back out to the backup lamps in the rear. Those wires are black/red and should not be tied together or attached to any other wire.

The same scheme holds for the red/blue wires for the neutral safety switch: the tranny is simply a relay/switch. Power for this system comes from the ignition switch, goes to the tranny, and back out to the starter solenoid. Tying these two lines together means that your tranny does not have to be in Park or Neutral for the engine to start cranking, and is a safety hazard.
 
On the tail shaft of the trans there should be a bracket with a switch that has either a pigtail already on it or provision for a couple wires to hook-up to the switch. All the switch does is basically open or close a "gate" to allow the voltage to pass when the trans is in or out of reverse. The two "chassis" wires connect to those two wires or switch points. Which goes where doesn't matter. Check the fuse too as with all your wiring "tries" you may have crossed something up and blown a fuse.
 
Switch is in place. Brought the two wires up through trans tunnel in the impression just behind the shifter hole. I assumed they were supposed to be connected to the two wires with the opposing male/female bullet connectors that were present under the console...one being the previously discussed blue/red wire, the other being the black ground wire.

All fuses removed and checked with a volt meter.
 
Blue/red is for console lamp; black is console ground lead. No, the NSS wires do not attach to those plugs. There's another harness specific for the NSS system (red/blue wires!).
 
There is another three bullet grouping of which one is green, one is black. Don't remember the other color. Two of these have 12V with the iginition on. When connected to either of these two 12V sources, the Dome light fuse blows. That made me think those were the console lamp wires.
 
Alright, I'm going to close this one out. Here is what I learned with swapping from a C4 to a TL relative to wiring for proper cranking/starting and backup lights. First, as before from the original problem I requested help with, the connector utilizing the blue/red wires must be shorted to itself for proper cranking/starting. Second, the black/red wires (at least under the dash and not necessarily at the other connector under the hood at the firewall) do NOT need to be shorted together. In fact, the blue/red and black/red are coupled together under the dash prior to entering the engine bay through the firewall. The black/red IS the feed for the backup lights and is clearly denoted in the schematics. The coupling of the blue/red and black/red is not. What has to happen is the two wires coming from the backup light switch at the transmission get coupled using one of these...https://www.npdlink.com/store/produ...re_back_up_light_switch-102123-2985.html...to the other connector which previously connected to the C4 NSS. These wires do in fact get full 12V from the accessory fuse via a wire at that fuse holder to a three pronged connector right behind the instrument cluster. So I pulled both connectors into the cabin and made the proper connections under the dash and installed a grommet in the open hole in the firewall.

Once I assessed the above, I found the source of why my backup lights only partially worked to begin with. First, I only had intermittent 12V at the three pronged connector behind the instrument cluster. So
I checked the wire going from the fuse panel to the three pronged connector...dead short. In doing so, I noticed the fuse almost fell out of it holder so I removed it, bent the holder tabs in towards the center and "snapped" the fuse back into place. Voila...constant 12V at the connector. Put the car in reverse, no lights. Disconnected the bullet connector at in the trunk...12V. Pulled the backup light bulbs...12V at the sockets. Looked at the bulbs...both good...wrong damn bulb. PO had installed incorrect bulbs and now I know why...no one in Huntsville stocks 1142 bulbs. Amazon Prime to the rescue...10 pack arrives tomorrow.

Hope this might help others who make the swap. Thanks for the help Midlife and Terry.
 
Just as a word to anyone who finds this thread...

The very best way to deal with ANY electrical issue on these old cars is to first establish what EVERY wire involved actually is. That is where it originates, connects and or terminates. 50 years later lots get changed (i.e. totally mucked up) by previous owners. Never assume just because a wire matches the description it is still doing the same work correctly. Once you have that sorted out, then go to a wiring diagram and/or schematic and gain an understanding of how a circuit is supposed to be connected and how it functions. After all that its very easy.

And don't be intimidated by electrical work. On our old cars it is about as simple as it gets. Aside from {.} I've never met anyone who couldn't, with a little guidance, figure out a problem and many have gone on to get a pretty good feel for basic electrical troubleshooting work.
 
Well said, but I do like the folks who are intimidated by electrical work: they keep me busy on the weekends and provide the funds for adult beverages.
 
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