Combination Meter Out After 12v Battery Replacement

@Liamzoot

Well I think it's a weird coincidence that the same "coincidence" happened to me and about a dozen other folks I've come across so far - within a week of replacing my 12V battery MY CM started to intermittently fail.

It's been occasionally going dark for the past year but it's so rare that I just keep driving cross-country and not worrying about it...I always have a maps app open and since it shows you if you're going above the speed limit I just keep track of how far I've gone (gas gauge gone of course) and when I stop I unplug the 12V battery for a minute or two and voila, it resets.

Someone is going to figure out the connection soon...not to say that there isn't also a massive problem with either construction or software as well, but there are too many actual instances of "coincidence" for me to believe that's 100% true!

 

ME TOO!!! Just posted to Liamzoot original inquiry about the battery replacement...that's not a coincidence although it appears to be multifactorial and perhaps ONE trigger is the battery replacement...other people have mentioned that lead was removed from the sodder, making it more susceptible to vibration...and perhaps multiple things can trigger malfunction of stuff on the CM but I'm super bummed that Toyota isn't just doing an optional recall if such a thing exists...

 

It could be (but I think this would be a rare convergence in the "force" LOL) that the old battery was low in voltage and the old cap was handling that OK, but was not up to the task of the higher correct voltage with the new battery. I can see how that could cause the event, but have no idea if it really did.

 

I have been living with intermittent CM black-out for the past 2-3 years. (2006 Prius)
The authorized dealer (Singapore) quoted the equivalent of about 2000 USD. Never mentioned extended warranty coverage. Pfft.
The black-out tends to happen when the aux voltage is higher. More often with a new 12V batt, and becoming less frequent as the 12V batt gets to the end of its usual ~2-year life.

Reviving the CM is a matter of doing this ritual:
- From power OFF, with key fob in slot, with driver door open
- turn on hazard blinkers
- turn on headlights and highbeam
- pump brakes slowly to get the vacuum pump to go
- usually the car will notify you when voltage is low enough by resuming the key-in+driver-door-open beeping. Otherwise you may also need to add key-fob insertion/removal once every 0.5 min to the above ritual.

 

2 years is not a normal length of service for an AGM 12 V battery.

It almost sounds like doing that procedure drags down the 12 V battery to a level where the CM can start successfully. This does not likely help your 12 V battery's longevity.

Wouldn't you rather spend US$150 (Matt @Texas Hybrid Batteries) to fix the CM once and for all and put an end to replacing batteries, and the inconvenience of that protracted ritual?

Start a conversation with Matt and see if he can help.

 

Perfect. I knew it had something to do with the battery swap I did. I had a weak 12v battery for last two years and the combo meter would sometimes come on and sometimes not. During the last few months it would come on 90% of the time as the 12v battery was on it's last legs. And if it did not I unplugged the white plug at the positive battery terminal and plug it back it to make it work. But since the 12v battery swap even that wasn't working. When I read your post, it made sense. Gave it a try. And Walla! The object is to drain the 12v battery to about 11.5v for it to work the combo meter(for my car). I turned all the inside cab lights on, high beam on, turned the car to on position with the AC fans on high and did brake pump. With the driver door open, the annoying open door chime came on after a couple mins. This is a temporary fix but works

 

As per my reply to pnerd, you do realize that draining the battery to this low level (technically beyond flat) that you are irreversibly damaging your expensive brand new AGM battery, don't you? This "workaround" is a very expensive one.

I hope this means you will be repairing your CM in the very near future. Matt @Texas Hybrid Batteries has a very affordable solution if you are a DIY person.

 

Well mine is not AGM battery. I put in a used refurbished battery for $50 bucks. Don't expect it to last more than a year.

Yes I know there is a permanent fix option with Texas hybrids but prob fix it myself when I get around to it.

 

Thanks, but I always get the cheapest batteries for it, "Amaron" or "Exide".
Anyways, about 2 weeks ago, I finally got around to doing the capacitor replacement for the combination meter of my 2006 Prius.
I followed the well-known YT videos about dashboard removal, like SB1dVFa3ofM , pb19p8zYeTg , and this video about the capacitors: 55cYjgZ0LBg .

Surprisingly, the PCB of my combination meter has a different layout. (Right Hand Drive for Singapore) But it was still pretty clear which were the capacitors in question. I replaced all 3 of them with thru-hole types, of equal or greater capacitance and voltage. They were significantly larger in size, but they seemed to fit. I used a normal fine-tip soldering iron (I had no hot air tools). My large solder-sucker wasn't very helpful in removing the SM caps. So in the end I just heated the pads while tugging on the cap with needle nose pliers. Tugged too aggressively on the largest cap, and tore off 75% of one pad! You can see it is the pad nearest to the "C2" label.
The green tape in the photos contains one of the new caps.

The capacitors I used were:
ELNA 35V 220 uF, 105C, 8x20 mm
ELNA 63V 330uF 125C, 18x22 mm
ELNA 50V 10uF 85C, 6x11 mm

Anyone else notice those curious Lichtenberg branching marks on the inside of the white plastic cover though?

The most difficult parts of the job for me:
- The two large bolts holding the front passenger's airbag were overtightened and seized. Applied WD40 and more muscle. This consumed about 1 hour, searching for different tools.
- Removing the dashboard after all fasteners were dealt with was hard.
- Putting the dashboard back in place was even harder. A kind of 3D puzzle.

So despite the ugly solder job, the Prius has been functioning perfectly for the past 2 weeks.

 

Why did you replace all three? Thought only one of them needed the replacement to fix the issue?

 

Yes, C3 is the one.

But I did all 3, just because I knew the difficult part was the disassembly and re-assembly, the capacitors are cheap and easy enough for me to buy, from my part of the world. And I saw that some other people also replaced all three, for these reasons. BTW, none of the old caps appeared bulging or leaking to my eyes, and all tested to have normal capacitance by my cheap multimeter.

 

I’ve read all the posts here and I thank you all for the info. Knowledge is power, right? I had an experience similar to many of you. I went into a store and may have left my 2007 Prius on and when I came out, all the dashboard lights were on and I couldn’t start the car. AAA came out and jumped my battery (no replacement) and all seemed fine. Two weeks later, I get in my car and start it and the back up camera would not come on and dashboard is dark. When I got to my Destiination, I couldn’t turn the car off. Googled what to do and finally got the car turned off. I am a 65-year-old grandma, not a DIY person, And will most likely end up taking my car to a dealer. Any idea what this should cost and what I should tell the mechanic or any other suggestion?

 

I think it will cost up upwards of $1k at the dealers. Why don't you buy the fixed combo meter online and take it to you indy mechanic to put it in.

 

Thank you very much for the info and for the suggestion. Unfortunately, I don’t know an independent mechanic around here to take it to, But at least I know now how much I Should expect to pay. It’s at the car dealer now but I haven’t heard back from them yet. It’s worth mentioning that my car started up like normal today and everything worked but I still figured I should take in

 

I'm sure you are solution oriented, however, I find it oddly suspicious that everyone's answer is to call Matt. A problem this consistent and there is only one seller? And what if I don't want to DIM?

My 2007 Prius 180k miles just went out after installing new duralast platinum battery so after reading all these posts I think it's safe to say it's no coincidence. Matt's website makes sense about the cold as I just moved from LA to Seattle but there is no DIY info nor links to an installer. Sounds like disconnecting and reconnecting are best bets this issue feels like it was made to happen on purpose if a random repair like this requires a solder. Tf?

 

There were more repair options in the past but Toyota had put out an extended warranty for this problem- up to 9 years, So most independent repair folks stopped doing them. Now that time limit is expired and there aren't many who will do this work.

If you don't want to do the repair yourself, or remove the CM yourself, then your options are to pay a shop to pull the CM for someone like Matt to fix, pay lots $$ to a dealer for a new CM, or just live with it.

Just be aware, eventually (few months, few years, who knows?) the problem will deteriorate enough that the CM won't work at all, which can make it difficult to turn the car on or off.

 

I would talk to a local mechanic, it is pretty simple to replace the meter. Unless you want to pay him twice it is best to order an upgraded or fixed meter online. I would say a regular mechanical could swap it out in about 1-2 hours. The part is between $50-$200 (depending on what you get) and a $50/hr mechanical should have the skills to do the job. It is more important that they be careful than skilled (as they will cost you more by breaking your vents and damaging your airbags).

 

So what happened?

 

Mine is a 2006, 160k km. Intermittent non-lightup of the dashboard, which got worse after a battery replacement. Temporary workaround is to lower the battery voltage by using high beam and pumping brakes before retrying the power button.

I crudely DIY-replaced the CM's capacitors in July 2020, and the CM, power-button have all been 100% reliable ever since.

 

Coincidence that I had just had my 12 v battery replaced?...same problem!