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No power to speedometer, odometer, driver information center heat or ac

Hey all, I just changed out my battery on my Oldsmobile Aurora and hours later, I have no power to my speedometer, odometer, ac or heater (blower no power) and my driver information center. I can’t find a blown fuse and there are fuses at the driver kick-panel and 2 boxes under the rear seat. Any clues what would cause this mass power outage? Please I at least need my speedometer and blower for defrosting (belt and motor just replaced)

The body control module may have lost bus communication with other computers/modules.

https://www.aa1car.com/library/battery_disconnect_problems.htm

Tester

1 Like

You might try a hard reset by disconnecting the battery overnight and try again. Sometimes it is necessary (with the battery totally disconnected first of course) to connect the + harness connector to the - harness connector so that any charge that has built up in the car’s electronic modules is drained too.

Hey George, Always nice to see the guys who keep this site reliable still here, and thank you for not telling me to get a new car (I am very soon finally, but need to keep this one alive for 2-4 months if possible). If it helps you to guess, and I do realize troubleshooting car electronics is hard enough in person BTW, I checked the fuses but not the relays/breakers as I don’t know how. There are fuses in 3 locations in a car with the Northstar motor, maybe 4…by the drivers left knee as always, then under the removable back seat, there is a box behind the driver and another behind the passenger with many fuses and breakers under the seat. I’ve been told there is a 4th under the hood but I never found it. I will try your suggestion. Thanks GSJ

Hey Tester, as with George, thanks for reaching out, this sounds plausible as with GSJ, was your copy/paste an article about this possibility? If it helps, I have had electronic problems with this car for years but couldn’t spend the $ to have it diagnosed, I will if this doesn’t work as I’m finally buying a new/used car soon, but need to keep this alive for just 3 months if possible, but I need my speedo and temp and air to defrost my windows. Just FYI I have burned out 3 new batteries this past year alone (huge $200 battery in this car) so there is a big vampire drain. Before I changed the battery on Friday I had no power to the engine temp gauge, the drivers side power seat, power windows, all interior lights, the cruise control, both rear view mirrors, but now I have no power at all to the air, no speedo/odometer, no drivers info center…and this is no pinched wire, too much of a coincidence that it all happened when I swapped a new battery. Oh, the radio and dash lights do work BTW, but no air whatsoever (blower motor is brand new and the belt is turning under the hood) Tommy

Hey Tester, it appears you have something here, almost everything in the article is what I’m dealing with, nice shot,…can you help me by suggesting what I can try if George’s idea doesn’t help? (disconnect the battery for 12 hrs). I have had the following I didn’t mention 1) The check engine light was on prior to me “going dark”, I was getting idiot lights telling me to check the coolant (it’s full and the radiator was operating fine, not overheating so false code) and the change oil message (which I do every 3,000 religiously). The car runs like a top so no engine troubles, I did do frequent OBDII scans and two codes came up in the last year, the downstream O2 sensor and the KAM module, I didn’t fix either, codes went away eventually, I just need to keep my car alive a bit longer so I need my air and gauges back. Thanks Tester

Please see my reply to Tester, there were other issues I forgot to mention. I am actually pretty good with electronics including auto but that was in my youth (I worked on Inertial Navigation systems of the F15A Eagle Jet Fighter in the USAF so I get basic electronics, but modern auto is much different. It is very unlikely that I have a single frayed wire causing this mess, and it wouldn’t have happened overnight, now the vampire draw I have killing batteries every 3 months surely caused the first list I gave you (no power seat drivers side only, power mirrors, cruise control not working, no interior lights at all). If it helps, long ago I pulled the drivers door panel off to replace a power window module and I did a sloppy job, tearing the plastic and I left the windows open when it rained, likely rain got inside the door and either shorted out something or I pinched a wire pulling the door cover off.

Does it really need an “overnight” time period? I’d see keeping it disconnected for 10 minutes to allow any discharge, but how does 8 hours etc affect any change? Thanks

George, I thought you meant the positive battery cable, where/which is the positive harness
connector on a 1996 Oldsmobile Aurora? Thanks

It might take longer than 10 minutes, but certainly should take less than overnight.

Not sure what you mean. If you aren’t certain what I mean, you should ask for some local professional assistance.

fyi … There’s capacitors all over the car that charge to 12 volts when the battery is connected. Disconnecting the battery can leave some of them charge at 12 volts which will power their circuitry for a certain amount of time. Those capacitors are connected on one end to the + harness connector, and on the other end to the - harness connector. So when you connect the two harness connectors together (with the battery completely disconnected) all the charge is drained from the capacitors, so they can no longer power the circuitry.

Don’t misunderstand, I’m more than grateful and acquiesce to your experience, asking questions is just how I learn…and your reply makes sense. I’m finally, after over 15 years getting a new (used) car as this one’s got more problems than I can afford to fix (all electrical), but I can’t drive a car safely with no speedometer, engine temp, any dash info from the ECM and not even air to defrost my window in the am, dangerous…So can you tell me where the positive harness connector is GSJ? Thanks

There is a small fuse box under my hood I just found, none of the fuses under the hood respond to a test lamp