Diagnostics port info

[Bmachine]

I was in the process of building a little ignition switch bypass using the diagnostics port (thank you @Stevehose ) and was researching which pins to use. Since it wasn't in any easy to find location I figured I would do a little post about it in case it is helpful for someone else. This is the 9 pin port with the orange cap located between the relays and brake fluid reservoir



Pin assignment: (in part from @decoupe)

1. RT : Battery positive
2. GN : Ignition on
3. BR : Negative (chassis ground)
4. Empty
5. Empty
6. Empty
7. SW or WS-SW : Starter
8. BL : Charge (alt light)
9. SW or GN-BR : RPM/Dwell



Diagram:

31: diagnostics plug
17: Battery
27: Starter
29: Unrelated connector for the black wire from pin 7 to piggy back on its way to the starter
Pin 1 goes to battery positive

 

[Stevehose]

Just make sure the wires are in their correct spots after all these years!

 

[Bmachine]

Just make sure the wires are in their correct spots after all these years!

Good point!

 

[ScottAndrews]

So what exactly is on these pins? For example is “ignition on” hot when the ignition is on , or does connecting it to “battery” cause the ignition to come on?

 

[HB Chris]

You can start the motor without ignition key being on, check dwell, rpm and voltage.

 

[ScottAndrews]

You can start the motor without ignition key being on, check dwell, rpm and voltage.

Ok so the “ignition on” pin activated the ignition without the key, and the “start” pin activates the starter.. I assume when these re connected to the”battery”. Soundsconvenient

 

[HB Chris]

One of the pins has power so yes, no other connections needed.