Mysterious power draw, even with all fuses pulled..

[guzerone]

2009 Boxster, base w PDK, stock except for springs, sway bars and front LCAs. When locked, it draws around 1.5A, then it goes down to 0.1 or so for a few seconds, then back up to 1.5A.

When it goes back up, there is a faint motor noise in the dash somewhere, like a blend door actuator (but it's not, it also draws 1.5A when I disconnect the HVAC controller). SO I started pulling fuses and even with all fuses removed, it still draws about 0.3A. What's interesting is that when I pull row B fuse 3 (control units for seats, steering column, TPMS, Alarm and tilt sensor), the current goes from 1.5A to 1.1A and when I pull row D fuse 10 (PCM 3 Terminal 30), it drops by another 0.5 A to 0.6A. It looks like some control module is keeping the whole car from going to sleep. I found a wedged fuel door actuator (bushing was missing) but after I fixed that, the power draw is unchanged.

Any ideas what it could be?

[RFM]

You need a PIWIS diagnostic device to see which/when modules are being woken up, possibly also to detect CAN-BUS errors.

[guzerone]

I have one but I never tried it with the car off and no key in the ignition. Let's see..

 

[Loren]

The key must be in the ignition and power on to use the PIWIS.

It can still tell you what any faults are (CAN-BUS) as well as module states.

[guzerone]

Hooked up the PIWIS and found all kinds of low voltage and CAN codes, I cleared them all and none came back. The only active code was PDK - U0418 CAN fault, brake.

Would that cause  the car not to go into sleep?

I drove it around to clear the PSM steering sensor code and locked it. I'll check the codes again in a few hours.

Edited January 1, 2023 by guzerone

[guzerone]

I let is sit for an hour and checked all control modules for fault codes again, nothing, even the PDK code went away.

What's next, unplug one control module at a time?