Interlock Safety Switch

4 on the floor said

Thanks for the help. I have a factory service manual. I know where the wires go so I wired the transmission harness the factory way. The previous owner did something to defeat the safety interlock so it will start without a transmission harness.

Maybe I have a bad switch / sender depth. If I hook up the new junkyard transmission harness just like it shows in the service manual but pull the plug on the transmission what holes do I connect to make the car start? (This will test the switch)

Click to expand...

I already told you how it works. The center pin of the switch is grounded. That is one wire. It goes from the start relay, one of the flag terminals, down the firewall to the NSS. So start by grounding the relay terminal and see if it cranks using the key. BE CAREFUL as you have bypassed the switch function

Then check the wire, either check continuity, or reconnect it and ground the center pin.

Also hook it up as it should be and hold the key into the start position while wiggling the shift lever from park to neutral, which will check for poor switch operation, linkage mis alignment, etc etc.