combination meter repair - DIY

There isn't the same kind of PriusChat record of gen 3 having a notorious meter capacitor issue, the way there is for gen 2. I suppose that doesn't mean one can't occasionally flake out.

 

Thank you for your response. I'm unlucky in that sense then. Started playing up when it got really cold in the winter recently.

I'm from the UK. Helps to know it could be more than one particular issue though. Thank you.

 

I followed a youtube vid to get it out

Another one for the repair

(I only changed the 10u)

And my vents crumbled so found replacements on Amazon that fit like and look OEM for $99
Edit: Seems like the site keeps trying to change my link to media for amazon. But search
4Pcs A/C Dash Air Vent Trim Plate Panel, Air Vent Outlet Frame Cover, Compatible with 2004-2009 Toyota Prius 1.5L, Replaces# 55670-47060, 55680-47020, 55475-47020, 55474-47020

Hope that helps!

 

so where is the repair thread? interested in knowing my options

 

You're replying to as good a thread as any. Read the first two pages then jump to about page 15 and read pp 15, 16, and 17. After that, you can read as much of the rest as you like.

 

Thanks for all of the info! I joined the forum today. Just inherited a 2007 Prius from my mom when she upgraded.

Just finished reading through 19 pages of this before starting to tackle this combo meter repair job.

I just put together a Digikey order for Combo meter parts today. I bought all of the surface mount and thru hole caps and the 5V regulator IC.
(I hope I got them right!, they're all low impedance/low ESR)
the whole order was $6.83 + $4.99 shipping - about $13 with tax.

I was going to post all of the links, but I'm not able to share links before I have 4 posts on the forum. If anyone feels like current links to digikey parts / part numbers / descriptions would be helpful, let me know and I saved it to post later on. Or I guess PM if you need it ASAP.

 

On my Gen 2 Prius I had the combo meter go out and I soldered in a new capacitor a few times. I didn't take the old one out, just put the new one in parallel. The first few times it worked for a few months until my solder broke, but the most recent solder job has lasted about a year. I also once damaged a ribbon cable with a screwdriver and had to order one from a local Toyota dealership. The worst part about the whole job here is taking the dash apart and putting it together. I've broken lots of brittle pieces of the air vent assemblies. I've also lost a few bolts into the void, and my car rattles when driving due to random bolts somewhere in the dash.

 

Don't leave the old capacitor in. It could potentially short out in the future which would negate any replacement capacitor in parallel with it.

For broken vents a source of (some) replacements is mentioned in this thread:

Dash vents I came across today while browsing.... | PriusChat

and aftermarket ones can be found on Amazon. For instance, on that site search for B0C7L4VWV7 and it will turn up a full set of 4 for $93.

 

Adding advice to NOT leave the old cap in. They do short out or just present a resistance that should not be there. Just pop it out. Not difficult to do. I used through-hole replacement cap on mine and it worked just fine. Several years and going. Car now has over 302K miles.

 

I was under the impression the old capacitor just slowly had less capacitance over time. Good thought about the shorting that would be really bad.

Putting two resistors in parallel reduces the overall resistance, so it shouldn't add any resistance to put them in parallel.

 

I don't understand your point. What matters is that any resistance in parallel with your new capacitor will cause it to discharge faster, essentially making it a lower value capacitor. Not what you want since you changed the capacitor because the old one had too low a capacitance.

 

When you put two capacitors in parallel, the capacitance adds together. If the bad capacitor was measuring zero capacitance, maybe it could be an issue, but I think the combo meter fails because the capacitance gets only slightly too low. There wasn't enough factor of safety designed into it.

I know that real capacitors aren't ideal capacitors, but the hope is that our capacitors mainly just add to the reactive part of the impedance and the real part is negligible.

Perhaps as the capacitors wear out this is a bigger problem, but I think the capacitors still measurably have most of their capacitance when the combo meter fails. I am under the impression the main design flaw here on the combo meter was that the capacitor they used was too small to begin with and just barely works.

 

That is all correct.

When repairing electronic equipment a defective component is typically removed from the circuit board and the replacement installed in its position. The circuit can be made to work by piggy backing components and other similar hacks, and that's OK for testing purposes, but if a change is supposed to hold up long term that sort of work is not so good.

 

Great thought. I definitely wouldn't want to do something hacky like this professionally. If it fails again I'll take the old capacitor off.

 

Might be a silly question, but anyone able to point me in the direction of someone near-ish Detroit that is capable of pulling off this repair start to finish? I'm reaaaallly out of practice on board level repair skills, and most definitely do not have the time to deal with a dash pull

 

From my experience and knowledge when i looked this up the issue was always the capacitor loosing its capacity to hold its rated/need charge. If you addressed that capacitor then the issue would be fix. It is like a 1$ part but the labor and other work to get to it to either add a capacitor to the weak one or remove it and replace is sad panda mode.

My CM went and replaced the capacitor and it worked fine.

I also read that you can have issues if you try to replace the CM . Stuff not meshing right computer wise. So its very beneficial to try and get your cm fix if anyone around is willing to do that work.

 

Don't do this.

If you're going to all the trouble to get to the CM, remove the failed capacitor and replace it with a new one.

 

Yup. I have on occasion temporarily soldered a second capacitor on in parallel in some piece of equipment, but it was always just to verify that there was a weak capacitor in that position. Because I couldn't test the capacitor properly since I don't own the needed test equipment.

 

Gosh, I haven't posted in a long time. I recently experienced the intermittent combo meter issue on my 2006 Prius. In my infinite wisdom, I sourced a complete dash (plastic cover with attached combo meter, airbag etc) from a 2008 Prius thinking it would be easier to replace the whole thing than just the PCB. After installing the new dash and making all the connections, I am getting just a check engine light when trying to start the car. MFD is working with a single press of the power button but nothing else. I am able to lock/unlock the car. Any ideas? Is a 2008 CM not compatible with 2006? Is there reprogramming involved?

 

Well, at the very least the odometer will be wrong, since that information is stored in the combination display. (Ours was replaced under a warranty by a dealer, they entered the odometer value from the previous visit when they ordered the replacement, so the odometer is off by a couple of hundred miles.) It would surprise me not at all if there wasn't some sort of identification handshake between the combination display and the rest of the car. Perhaps something like, "my VIN is XYZ, what's yours?" To which some other module responds "ZYX, intruder alert! Do not READY!"