MicroSquirt.com read only forum (Jan.15,2018)

i'm starting to get the hang of this thing ,but something still puzzles me. i have tried to read everything i can find and search the forums as much as i can but i still can't figure out how to wire things for the spare ports. i found the stuff on controlling 5 volts ref. to a gm hei module. and in works great, but how do i use one of the other spares to control, say, the downshift relay for my turbo 400 transmission? i have no tcc to deal with and the downshift just has to work under w.o.t. i figured i can just say to come on under 90 or 100 percent tps volts. but how do i, if i even have to, get to a wire in the db37 to run to the relay.
ms-2 v2.36
v3.0 main board wired for step iac


thanks

monte85,

Because the spare ports are used for a variety of functions (or not used at all) they are in various states of readiness for use.

For example, you could use the FIdle port (DB37 pin #30) directly witth a relay for the electric kick-down. Thi is because it it already set up to control the FIdle vlave.

However, since you are using the FIdle port for the HEI bypass (I assume), you have to use one of the other ports. Either of the IAC ports will work directly (for up to 0.5 Amp, or you can use them to control a relay), but you may be using an IAC stepper.

The LEDs can also be used with a relay, if you don't mind loosing their original function. You would jumper a wire from one of the spare DB37 pins (3,4,5,6) to the hole on the 'flat' side of the LED (closest the DB9), then use the DB37 pin you have jumped to to control a relay that sends 12 Volts to the kick-down.

Not that if you are controlling a relay, you will generally be grounding a 12 Volt source, and you will need to remove the LED to avoid putting 12 Volts into the 5 Volt supply.

For example, if you use the Accel LED (PM4) and DB37 pn #3 for this purpose, you would remove D16, then jump from SPR1 to the hole for D16 closest the DB9. Be sure to check the operation on the bench, with the transistor in the path it is easy to get the conditions 'backwards'. You would run a wire from DB37 poin #3 to the relay pin 85, 12 Volts to relay pin 86, 12 Volts to relay pin 30 (with an appropriate fuse, of course), and relay pin 87 would be connected to the kick-down solenoid.

Finally, one spare port (knock enable - PA0) has no circuitry at all associated with it, and you would have to duplicate the Filde or LED circuits in the proto area.

Lance.

well, i was using the Fidle for my bypass, but after thinking more about it, i might go back to the relay control like the hei section shows. i have a fuse in my fuse block the has voltage in start but not run. i'd like to limit the use of crazy relay circuits as much as possible. keeping the kickdown is higher on the list for me anyway. what pins are used with the knock enable port? is it different than the knock/spark control stuff i see on the site? thanks for taking the time to answer all these questions.