Options switch for map choice

[david jenkins]

Brent,

Can you tell what the wiring arrangements are for the 'map switch' that will be connected to the 'Options' connector?

I have just finished installing my MJ unit into my car (successfully!) and now would be a very good time to install the extra wiring, in preparation for the firmware upgrade.

Thanks,
David

[brentp]

Hi David,

I'm working on updating the documentation for that, but in short- there are a few options:

(For V3 hardware)
TPS controllers: use the 5V vref output to toggle the port between high and low (3 wires going to switch)
MAP sensor: requires a small internal mod to either pull up the signal to 5V and use a switch to pull it down, or enable the 5V Vref port and wire it like the TPS controller.

For V2 hardware you will need to have some more extensive mods, but the theme is similar.

Note the dual map option is not enabled by default, you have to turn the feature on by editing the global configuration options in the V3.1 configuration software.

Brent

[david jenkins]

I thought it would be something like that - many thanks, I can make sure that I have the connectors in place with wire stubs ready for the connections!

cheers,
David

[aarc240]

A different solution on a V3 that works for me was:
1 install a 1k resistor across zener diode D1 (under the board)
2 drive the option input from a switched 'ignition' source through a 120R resistor

The 1k ensures port B7 will go to 0 when the switch is off and the 120R will limit the current when the switch is on.