Weird thing happened..

"LJ909" (lj909) 03/15/2016 at 00:59 • Filed to: None

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So I got a new battery in my car about two and a half weeks ago now, and since then ( as you can obviously see above) my odo and trip computer won't work and I'm not sure why. Before anyone thinks the guy that changed it did something wrong, he didn't. It was a simple unscrew the connectors, take the battery out,red crew connectors and drive off. Since the day I left the trip computer and odo won't read. I get my odo readings from OnStar who keep track of it apparently. So anyone knows what could have gone wrong?

bob and john > LJ909 03/15/2016 at 01:02

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needs to be re-programmer? IDK, i’ve heard of BMWS needing something to be re-done with a battery change.

that OFC, you have to take to a dealer to do.

TheOnelectronic > bob and john 03/15/2016 at 01:11

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I think the thing with BMWs is they have special programming to “condition” the battery, and if you change to a different type without altering that programming the battery dies really quickly.

Flynorcal: pilot, offshore sailor, car racer and panty thief > bob and john 03/15/2016 at 01:41

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Registering a battery isn’t that hard and it’s not the case here.

The magnetic doodad that senses your cam shaft turning broke at the same time you replaced your battery. Wire knocked loose, I’d imagine. Batteries are heavy. Shit happens. It’s not the battery but probably where you rested the ingoing or outgoing battery that pulled a wire lead off of the sensor.

AMGtech - now with more recalls! > Flynorcal: pilot, offshore sailor, car racer and panty thief 03/15/2016 at 02:18

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It’s not a loose cam sensor wire. If that were the case there would probably be starting issues and probably a CEL. And it’s got odo issues, not tach issues, I don’t know of any cars that use any engine sensors for odo (tach of course, but not for mileage). The odo is going to get its signal either from a discreet line to the ABS or powertrain (wheel speed sensor or vehicle speed sensor) module or over a CAN network.

Flynorcal: pilot, offshore sailor, car racer and panty thief > AMGtech - now with more recalls! 03/15/2016 at 02:50

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You’re right. Also, you’re right. The CAN network ties into both odo and trip computer, yes? I was thinking lousy input but it might not be the sensor end but the reporting end of things. The trip computer would incorporate a fuel level and/or fuel flow.... which does show up though. Hrm.

Hey LJ909, have you checked your fuses? Also, why did you change out your battery? If you alternator is malfunctioning it’d explain everything from needing a battery to your display not working correctly really. Agreed AMGtech?

AMGtech - now with more recalls! > Flynorcal: pilot, offshore sailor, car racer and panty thief 03/15/2016 at 03:08

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Presumably, the whole instrument cluster is it’s own module which controls the outputs for everything it displays. So it would likely have a single CAN connection from which it received all necessary information (temps, fuel info, speeds of all sorts, etc). Though I’m not familiar with whatever this car is specifically.

Possible, though I suspect other issues would be present along with a faulty alternator. Considering how I suspect the cluster works I’m leaning towards either a faulty cluster or some coding/programming/registration/resetting/teach-in sequence or procedure. Basically, a logic problem is my suspicion, because all other functions appear to fine which rules out data delivery. Although if it gets its data from more than a single CAN connection (i.e. more than two CAN wires) then the issue may not be the cluster but rather the data source or conveyance. I would need to run faults for the whole vehicle and see a diagram for the cluster. Though a tech familiar with this car will probably know what to do immediately.

Flynorcal: pilot, offshore sailor, car racer and panty thief > AMGtech - now with more recalls! 03/15/2016 at 04:05

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I just looked up what the battery registration was all about as I had forgotten. It’s for AGM batteries. The charging cycles is battery dependent and you can fry a battery by not re-registering it. So ‘good to know, but won’t affect the ODO’ as B.I.G. used to say. (I made that up.)

My advice to the OP would be to disconnect the new battery and let the car sit for an hour. This will cause the car’s brain to forget and re-learn re-adapt everything from the battery to the clutch, depending. Things like airbags have their own battery and will outlive the car, so you won’t break your shit by having the power off a while. If it’s logic or coding, which seems super likely and AMGtech seems really on the money, that’ll reset your vehicle’s computer. So possible solution.

Not knowing your vehicle and speaking generally, when you shut off your car the computer goes into standby. Then it’ll go into a deeper standby after the alarm is set and 15-20 minutes go by. It’s possible that you hit a hole in one and the computer is confused about WTF state it’s in and yanking the power and leaving it out a while will re-set it.

It won’t hurt anything, that’s for sure. An OBDII code reader will tell you what’s wrong too, but if you haven’t gone that way already on your own it’s too much of a subject for here.

jimz > AMGtech - now with more recalls! 03/15/2016 at 06:49

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depending on the electrical architecture, the cluster is frequently a “gateway” between multiple CAN buses.

jimz > Flynorcal: pilot, offshore sailor, car racer and panty thief 03/15/2016 at 06:50

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are you just guessing here?

functionoverfashion > LJ909 03/15/2016 at 09:43

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Before changing the battery on my wife’s 2007 X3, I had done some “research” by which I mean reading PanickyPete’s posts on the bmw forums. Sure enough, PanickyPete was out to warn the world of potential dire consequences (such as a trip to a dealer) of disconnecting the battery while changing it.

Rather than face the wrath of the internet - or have to drive an hour and a half each way to the nearest dealer - I used a small power supply to give 12V to the car while swapping around the batteries. I can’t say if there would have been any issue, but it was too easy to provide continuous power not to do it.

Just a thought for next time.

TheDudeAbides_(version 2.0) > functionoverfashion 03/15/2016 at 09:52

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I did the exact same thing in my ‘06 3 Series a few months ago. I connected the jumpstarter pack I have to the jumpstarter leads under the hood, and then very carefully removed and replaced the battery. Happy to report that even though I don’t know if it was necessary, I’ve had no issues since, and I didn’t have to reset my radio presets either; that alone made it worth it.

This also works for Hondas that basically brick the head unit if power is removed and you don’t have the code to reset it.

LJ909 > functionoverfashion 03/15/2016 at 10:09

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I thought about something like that might be it, but the thing is all the other information in my Drivers Information Center saved, such as my average MPG, engine hour timer, etc. Its just the trip computer and odo that arent showing up for some reason.

AMGtech - now with more recalls! > Flynorcal: pilot, offshore sailor, car racer and panty thief 03/15/2016 at 10:26

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Yeah, AGM blah blah blah. But you never know what kinds of glitches or weird logic sequences might be in play here that are related to battery registration or whatever that manufacturer calls it.

Disconnecting modern car batteries isn’t as effective as it was 10-15 years ago. Not everything will reset, some cars do a better job of this than others. Airbags have no battery. Some modules may have capacitors that take a little while to power down. But most cars still only have one battery, maybe two (one very small one) if they have engine start/stop features. You are correct though that leaving the disconnected won’t hurt anything. But to be honest I don’t think it will help either, since that’s how we got into this whole situation.

Unfortunately a generic code reader won’t get you anywhere in this situation. You need a factory compatible tool that can read more than just powertrain, SRS, or even ABS faults. And even more importantly it needs to be able to read UXXXX codes, which denote communication issues. Even more importantly than that it will need full menu and function access to every module on the car.

AMGtech - now with more recalls! > jimz 03/15/2016 at 10:30

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True. But I’m not familiar with this car specifically. Assuming it isn’t a German car I’m going back about ten years in my head as far as terminology goes, in which case the car maybe only has one CAN (pretty sure most cars do still only have one).

jimz > AMGtech - now with more recalls! 03/15/2016 at 10:38

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I can only speak about the domestics, but when Chrysler went to CAN in 2004 they had 2 or 3 depending on vehicle; high-speed for powertrain, and medium/low speed for body and interior. some of the newer Fords have 3 or 4 networks. I’ve no idea about GMLAN though, I think they’re using single-wire.

AMGtech - now with more recalls! > jimz 03/15/2016 at 15:04

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Yeah I don’t know anything about them either. I haven’t worked on domestic or Asian cars regularly in almost ten years, and even ride were well out of warranty and typical didn’t have a CAN at all. Everything I work on these days is minimum 5, plus MOST, plus LIN, and maybe flex-ray. That’s before we even start talking internal wi-fi and bluetooth communication.