More information:

I'm definitely getting power on the OVMS -> OBDII cable. 11 volts when the car is off, and 12.6 volts when the car is on. I'm assuming this is quite deliberate. (And like 0.2 volts when the power to the ext12v is off).

By default, the HUD was needing (according to docs - probably) 13.2v to trigger it to turn on.. so I connected it directly to the car OBD and changed that setting to 11.5 volts.

When I turned the car off (still connected directly).. the HUD remained on as it was still getting > 12V.. so the setting definitely worked.

Unfortunately when I then connected the OVMS to the OBDII and the OVMS -> OBDII cable to the HUD - it still didn't turn on. :( (oh and yes - "power ext12v on".

Any thoughts on this would be welcome.

//.ichael

On Sat, 15 Oct 2022 at 07:15, Michael Geddes <frog@bunyip.wheelycreek.net> wrote:

Hi all,
Anybody got any experience with HUDs?

I bought this simple HUD from FastTech:
https://www.fasttech.com/products/9686283
When connected direct to the OBDII port, it powers on and seems to function. When I connect it to the OVMS module with the standard https://www.fasttech.com/products/9652027 the HUD doesn't even power on.

It's stated draw is 200ma which afaict should be fine. I'm pretty sure the 12V power is getting to PIN 16... though I will try again to make sure. I only have a crappy little Multimeter.

On the Troubleshooting it states:
"HUD only available for cars with OBD2 and EU-OBD agreements ... HUD Products don't support JOBD and OBDI protocol."

The OBD HUD connector has the following pins:

4* Chassis

5* Signal Ground

6 CAN High

7 ISO9141 K Line

14 CAN Low

15 ISO9141 L Line

16 Vehicle Battery +ve

* Long pins

These are the standard OVMS supplied pins:

4 Chassis Ground

5 Chassis Ground

6 CAN H (Primary)

14 CAN L (Primary)

16 +12V

So obviously the main difference is the lack of K / L lines in the OVMS ... but I wouldn't have thought that would have prevented it from powering up.
Does anybody have any thoughts on this?
//.ichael