I did some work on my 09 RAV4 today to install heated seats. Since it would involve disconnecting some of the airbags, I removed the negative terminal from the battery and waited for the system to discharge so I wouldn’t have one of them blow up on me.
After I was done I put the battery terminal back and started the car, and it started and seemed to run normally but the dashboard was lit up like a Christmas tree with seemingly random warning lights that did not go out. I stopped it immediately. 10 minutes later I tried again and the lights went out after a few seconds as normal and everything seemed fine. Did I mess up on the wiring or did the engine computer get confused at having power removed? Any thoughts?
IANA mechanic but yes, it’s possible for the computer(s) to glitch when they reboot after a battery disconnect. I once had my dashboard instrument lighting not work after a battery disconnect – at night the whole dash was dark. It turned out to be a known glitch that sometimes happens on computer restart. In my case the problem didn’t go away, the solution was to pull a particular fuse and reinsert it to force another restart, and my dash illumination was back. It’s amazing how much stuff those onboard computers control, it’s not just the PCM.
same deal as WolfPup, It happens occasionally with my car, due to a glitch, I lose all function of the IPC (instrument cluster panel) and I have to literally touch the + and - wires together then reconnect them to the battery for it to come back. I don’t know why it works, but it does (it doesnt make any sense) That being said, my car also does that when I remove the battery, everything lights up and sticks around until i shut it off and turn it back on (at least in accessory mode). Its normal on many cars, somewhat like a diagnostic mode or POST (power on self test)
I have a Citroen C5 - not available in America.
There is a quite involved procedure to disconnecting/removing the battery and replacing it - they are also very sensitive to reduced battery voltage.
Failing to follow the procedure can in some models cause havoc and bricked navigation aids.