2011 TDI SL is it Positive Ground?

[mrainbolt]

I added an external jack to plug in a homemade battery pack (14.4v). Let me RNB battery go when I sold my MXT.
I mounted the female socket on the top chassis. With chassis top and bottom still open/seperated everything seemed to work great. Nice steady threshold, good detection.

Connected top and bottom chassis, applied battery and had no power. Seperated chassis I have power. Measuring voltage, positive voltage on bottom chassis, ground on top chassis from female jack. (Smoked Q8 by reversing voltage - dumba**. Have ordered a replacement but this still doesn't change the question)

Disconnected the battery and removed the top chassis and all connections. Started ohming.
Neg battery screw to chassis - open
Pos battery screw to chassis - closed - zero ohms
Pos battery screw to W2, W3 and W4 (grounds for coil connections) all closed - zero ohms.

I have to assume this is by design. If I am correct will just need to isolate/ insulate power jack from chassis.

Is the TDI a positive ground system?

Thanks,
Fred

[Carl-NC]

Yes, with all TDIs the +Battery is system ground.

[mrainbolt]

Thank you Carl for your time and knowledge.

Do you think I smoked anything else besides Q8 with reverse voltage?

Fred

[Carl-NC]

I don't know, I'm not quite sure what you did wrong. If you connected your external battery to Batt+ and Batt- in the usual way (which your red & black wires suggest you did) then that is correct. But if you had it backwards then Q8 is likely the only damaged component.

[mrainbolt]

Great, I've order a FQT7N10 replacement. I don't know what I was thinking. Decided to hook the voltage up backwards? My learning curve spikes.

Thanks again for your help.

Fred