# Dashboard lights on after disconnecting battery?
**URL:** https://boards.straightdope.com/t/dashboard-lights-on-after-disconnecting-battery/798260
**Category:** Factual Questions
**Created:** [October 7, 2017, 9:28pm UTC](https://boards.straightdope.com/t/dashboard-lights-on-after-disconnecting-battery/798260 "2017-10-07T21:28:14Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Mdcastle](https://boards.straightdope.com/u/Mdcastle)
#### Post date: [October 7, 2017, 9:28pm UTC](https://boards.straightdope.com/t/dashboard-lights-on-after-disconnecting-battery/798260/1 "2017-10-07T21:28:14Z")
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?
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### Author:  [@wolfpup](https://boards.straightdope.com/u/wolfpup)
#### Post date: [October 7, 2017, 9:57pm UTC](https://boards.straightdope.com/t/dashboard-lights-on-after-disconnecting-battery/798260/2 "2017-10-07T21:57:11Z")
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.
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### Author:  [@anomalous1](https://boards.straightdope.com/u/anomalous1)
#### Post date: [October 8, 2017, 6:51am UTC](https://boards.straightdope.com/t/dashboard-lights-on-after-disconnecting-battery/798260/3 "2017-10-08T06:51:53Z")
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)
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### Author:  [@Myglaren](https://boards.straightdope.com/u/Myglaren)
#### Post date: [October 8, 2017, 11:15am UTC](https://boards.straightdope.com/t/dashboard-lights-on-after-disconnecting-battery/798260/4 "2017-10-08T11:15:49Z")
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.