So this is a cautionary note about using battery chargers whilst the battery is still connected.

Typically I keep the battery connected when charging, simply because my radio loses all it's settings and stations when disconnected, a real PAIN !

Back on Jan 5th my Tech2 died, shortly after that the truck battery went very flat, the weather was cold and we were locked down do to the Covid plandemic, so the truck stood idle for a couple of weeks

When I connected the charger, a few relays started clicking (probably the AS) so I quickly disconnected the battery and charged it separately.

When I re-connecting it, I got the "Service Air Suspension" message, but without a Tech2 it was hard to troubleshoot.

With my Tech2 repaired I saw the AS DTC C0563 was set, meaning as follows:-

"On the power-up self test, the calibration data stored in the electronically erasable programmable read-only memory (EEPROM) is copied to shadow RAM. Data checksums are generated and verified, and the data in shadow RAM is verified against the contents of the EEPROM. In certain situations data is written to the EEPROM. In these circumstanced any checksums are recalculated, and the data written to the EEPROM is read back and compared with the original data."

So effectively the Air Suspension Moudle's data had become scrambled, probably caused by the battery charging activity.

Of course until this DTC is cleared i.e. ride height re-calibrated, the compressor will not operate, so I couldn't drive the truck!

It was a quick fix, and for some reason the ride-height returned to it's original point when re-calibrated.

This was all my fault entirely, but I wonder how many times this has happened to other people, particularly as flat batteries are a common theme ..?

 

Hmmm.... I always do the same as well and connect a charger up when working on it. The GM docs even state to have one connected when doing any programming with the Tech2 to assure that things cannot die partway through a write function. When I do disconnect the battery I have a OBDII connector that I plug on first with a 12V power supply connected to that so I do not lose any settings (as well as potentially losing long term fuel trims, etc which can take a bit to settle back in). The OBDII one I got on Amazon. Was like $10 and is a nice gadget to have handy.

Another I did find out recently. Do NOT weld on your frame without disconnecting the battery...... Used my MIG on my GMC truck to re-attach the trailering plug bracket back onto the tow bar (bolted to the frame). Figured I'd seen exhaust welded on with MIG welders dozens on times without issue so I just clamped the ground onto the tow bar and went at it. Totally ruined my battery.

 

2A charge MAX(battery connected)!

 

Indeed I'd set it to trickle charge, of course it may be just coincidence.

 

I use Optimate battery (tenders) and recently bought a the top of the line Optimate 7 and it has a neat feature where you can supply a straight 14.7 volts to use while programing or scanning your vehicle.

 

Also took out my HVAC controller module....just found out.