I just don't want the mechanic to pull a fast one when all that may be needed is a new bulb.
What you're basically asking for is the service manual. Which is fine, I'm in favor of everyone who wants one having a copy of the service manual for their vehicle, however obtained. But that doesn't need to be onboard, nor are 98% of owners going to even want it. They want what they critically need to know, no more, but often it takes years
of analysis and interaction to parse out the important consequences and figure out what someone DOES need to actually know.
EG: The Volt has been out for over a decade. Only in the past (what would you say, Steverino? obermd?) two years have we learned that when the CEL comes on, the car pops up a message saying "Propulsion Power Reduced" and the generator starts screaming up to about 4000 RPM that the critical thing to NOT DO
is immediately pull over and turn the car off. Because on page 4427 of 8110 in the service manual is part of DTC P0AFA, subsection Action Taken When the DTC Sets
, it says:
• DTCs P0AFA and P0AFB are type A DTCs.
• If any of these DTCs are set, the vehicle will operate in a reduced power mode and charge sustaining mode.
• Once Vehicle Power has been turned OFF all of the contactors will be prevented from closing
. [emph mine]
Which means (probably anyway, now that we've had 10 years looking at it) that one battery cell group is critically low, the car is desperately running the generator trying to charge it up, the DTC may clear when it is charged up enough, and if you turn the car off before that charging up happens, the car will disconnect the main battery and you'll need to be towed to a dealership to get it unlocked. So your best course of action is to drive straight to your dealership anyway so they can just push it into a service bay when they have one. It's in
the manual, but it takes a long time to find it and suss out what it means.
So what does that mean for the EQ? That DTC is probably going to be in there, in some form, somewhere in another 8000 page manual. A code that says a battery cell in one of the Ultium modules is way out of line with the others, and what happens when that condition exists is going to need to be puzzled out so that owners know the best way to handle the condition: is the car going to recover with charging? Is it going to disable the whole main battery? Is it going to lock out a module? Half the modules? The whole pack? We'll need to sort that kind of thing out. As a community and with reports from people experiencing problems so we can read an index and find the page where it says "battery will be disabled if you turn off vehicle power" and tell people "if this happens when it 'shouldn't', then DO NOT TURN OFF POWER, drive to someplace safe with plenty of room in front of you for a tow truck before you turn it off." Or whatever it is for whatever condition that comes up.
But putting that in a display in the car isn't feasible.