March 31, 2025, 05:26:02 PM

Author Topic: FD Rx7 constant/switched power source  (Read 1240 times)

Offline jrpontiac

FD Rx7 constant/switched power source
« on: June 29, 2024, 07:44:07 PM »
Hi All,
I've recently picked up an LS1/t56 swapped FD.   The project was started 10 plus years ago but never finished.   The car is tacky but complete, the engine swap wiring was a disaster so I am cleaning that up. 

My problem is I can't find a wire that is 12v while cranking and in run position.  So while cranking the PCM is getting no power.  I did connect the pcm ignition wire to constant 12v and the car starts right up, but is have to pull the jumper to turn the car off. 

 I'm using the starter wire in the left side engine connector (x11 ) to trigger the starter and the ignition wire (run) in the (x11) connector to trigger my switched power relay.  The problem is the ignition wire has no power when cranking so my PCM isn't doing it's thing.   Is the ignition wire in the x11 connector supposed to have 12v when cranking? I tested it and it does not.    I also looked at the black wire in the x-5 connector, same issue. 

Where is the start/run wire?

I've searched through the forums and googled, using Granny diagram as a reference, having no luck.   

Help?

Offline digitalsolo

Re: FD Rx7 constant/switched power source
« Reply #1 on: June 29, 2024, 09:15:40 PM »
This is going deep into memory here as I've not done a swap in a minute, but I believe the Black w/ white stripe wire in X-03 (ignition switch) is hot in start and run.   Double check me though.  ;)

Edit:  Double checked the wiring diagrams (I'd suggest looking at those, they're in the General Tech stickies section of the forum).  Confirmed, X-03 Black w/ white should be what you need.  You're welcome to look at where it goes from there pre/post fuses, etc. depending on how you're handling the wiring and relay control.
Blake MF'ing McBride
1988 Mazda RX7 - Turbo LS1/T56/ProEFI/8.8/Not Slow...   sold.
1965 Mustang Coupe - TT Coyote, TR6060, modern brakes/suspension...
2007 Aston Martin V8 Vantage - Gen V LT4/TR6060, upper/lower pullies, headers, tune.
2021 Tesla Model 3 Performance - Stock...ish.

Offline jrpontiac

Re: FD Rx7 constant/switched power source
« Reply #2 on: June 29, 2024, 10:01:09 PM »
Thank you, I'll look into this.

Offline jrpontiac

Re: FD Rx7 constant/switched power source
« Reply #3 on: June 30, 2024, 10:39:49 PM »
Traced problem back to the ignition switch and determined that B1 was getting power but B2 was not.   Traced the B2 problem and fixed, I now have my ON/Start source.