combination meter repair - DIY

Pics with VFD removed, wrong byte order and correct order.

Unless you are familiar with and have the proper tools, I'd have to say removing the VFD and eeprom is not DIY.

Ordinarily the eeprom is in-circuit-programmed but that is military grade secret to be kept out of the wrong hands!!

Hope that helps.

Big shout out to Matt at Texas Hybrid Batteries :O)

 

I agree with OBJUAN, removing the VFD without damaging it is not easy and I'd definitely leave that to the professionals. Fortunately, if you're repairing your own meter (instead of a donor from a different car) then pulling the VFD and EEPROM shouldn't be necessary, and swapping out the three suspect capacitors is fairly straightforward.
I'm really impressed by the number of people giving good advice and willing to delve so deeply into this car's technology.

 

If you are repairing a failing/failed CM then replacing the regulator may be necessary as the failed
cap could have cause the regulator to self oscillate and possibly damaging it. My CM units never failed,
just doesn't get so hot here (great white north) to thermally stress the caps and dry them out. I replaced
the usual suspects since I had the CM out, takes a few dollars in parts and 1/2hr. Replacing the regulator
will take a little longer. I did check the ESR of the old caps, they were still in spec. I also added another cap
to C5, literally stacking it on top of the original. This doubles the restart time giving the regulator more time
to stabilize. The blue goop can be pulled off (sometimes) but 99% isopropyl will dissolve it. Exercise anti static practices....

 

It's my turn to deal with a failed combination meter on my 2007 (125K miles on odometer). It's not easy to remove the dashboard panel; kudos to all who have taken this path previously. I decided to get a replacement from Matt at Texas Hybrid, thanks to him for freely sharing his knowledge with the group earlier in the thread and providing a reasonable alternative to those who do not wish to deal with the surface mounted components.

I broke the vent panel immediately to the left of the MFD, as the silver plastic near the top had cracked. I'll probably get a used replacement from autobeyours.com, or else buy a new part as those aren't too expensive.

I'm not pleased with the solder workmanship on the original combination meter. Most of the through hole pin solder connections are cold solder joints, although they are not in the immediate vicinity of the surface mount electrolytic capacitors that are the suspect parts. The photo showing these poor joints depict the pins associated with the transformer located on the far right of the board, as well as some of the through hole electrolytic capacitors.

 

Sort out your CM yet? Lots of DIY info here....

 

Considering the number of VFD pins, I am amazed you were able to remove/replace that display two times and not cause damage to it.

This is the first report I've seen about the through-hole capacitors failing. Clearly those are much easier to replace. Why not replace those failed parts, then reinstall the board in your car? Then you don't have to worry about reprogramming the odometer reading on your new board...

This is a very interesting finding. The mating plug for the small socket has six wires, which connect to two three-terminal modules. Maybe they are inductors, I can't tell for sure.

I have no idea why the North American CM would have this while the European CM does not. The only difference I am aware of (other than miles vs. km odometer) is the 5,000 mile MAINT REQD light in the North American CM.

 

Electronics tech for 40yrs, a pace desoldering station and a hot air station for the eeprom...
Each attempt took about 40 minutes, all to manually read/program the eeprom..
Not something to even attempt with solder-wick or a manual solder sucker.

For the through hole caps, make a blob of solder to cover both leads (0.1 to 0.3 spacing) heating them
simultaneously while gently pulling on the cap body(<10 secs). Done right, the cap will almost drop out
(minimal force) and a manual solder sucker will easily clear the holes. Pencil soldering iron about 25 watts,
standard 60/40 electronic solder. Clean with 99% isopropyl alcohol. Practice on scrap circuit boards..........

 

I think the modules are the famous "inclinometers" that are used along with the in-tank sensor to guess at the fuel level in our bladder-equipped gas tanks. European models don't have the bladder, and therefore I assume they use a different tank that doesn't care as much about how tilted the car is - so the inclinometers aren't used.

 

I'm pretty certain this is correct. That was also the speculation in the (now very old) tear-down analysis from EE Times: https://www.eetimes.com/document.asp?doc_id=1281285.

 

Obijuan - I did buy an expensive capacitor tester but have gone no further. I could order the parts soon I guess. I'm not sure I have a small enough soldering iron for those surface mount caps.

Love all the info available on this forum. When I get up the nerve I probably will tackle the repair.

 

This thread has mostly been a discussion of the failed combination meter components: what they are, how to replace them, and potential repair sources for those who do not wish to personally repair the CM. I would like to expand the discussion to cover issues I faced and resolved in removing the black plastic dashboard. Also refer to post 19 in this thread which provided the factory repair manual info relative to removal of the CM.

1. Removing the four silver plastic vents: They pull out horizontally. A plastic trim removal tool might help you to exert that horizontal force to loosen the clips holding the vents in place. I broke the top of the left inner vent (the one that the shift knob pokes through and the P button fits within) as the plastic started to crack as I was pulling the vent out. The new part costs around $150 if you buy from one of the dealers that sell discounted parts over the web.

2. Separating the yellow plastic wiring harness connector for the passenger airbag: After you remove the upper glove box lid, you will see an oblong hole and a large yellow connector. That is for the passenger airbag. The way to separate the two parts of the connector is to first pry the connector up, away from the tubular pipe that runs the width of the instrument panel. Then, look at the far right end of the connector assembly, which was not visible until you've removed the connector from the pipe. Insert a small flat blade screwdriver between the latch on the far right and the connector, to release the two parts. This took me a pretty long time to figure out.

3. Removing the plastic trim that covers the A pillar interior and the curtain airbags: You first have to pry up the small plastic pieces that cover the defrost vents at the base of the A pillars. Use a plastic trim removal tool or a flat blade screwdriver whose tip has been taped to avoid scratching the plastic, Also use masking tape at the base of the A pillar legs, so that as you pry up the small plastic, the edges do not scrape the A pillar trim. After you've removed the small plastic pieces, the A pillar trim is secured by one clip at the middle of the A pillar, as well as a strange looking hook near the top of the A pillar. You have to rotate the hook 90 degrees using a flat blade screwdriver tip, or maybe long nose pliers, to fit the hook through the rectangular hole that it mates with. On my car, the driver's side trim rectangular hole had a crack in it, and on the passenger side the hook was beginning to break as the plastic was becoming brittle. (The instrument panel had previously been removed by a dealer a few years ago, related to replacing the skid control ECU under warranty.)

4. Removing the two ribbon cables that connect to the combination meter circuit board: The connectors that mate with the cables have a lock that can be removed by pushing down on both sides of the lock using a small flat blade screwdriver. Be gentle with that to avoid damage to the plastic lock or to the cabling.

 

Didn't need the cap meter if your intention is to just swap the caps, no need to test them.
Texas Hybrid batteries supplied the component list links on page 4 in this thread, copied here.
If your CM did fail, then replacing the regulator would be prudent. Mine did not fail(yet)
and the new regulators had not arrived so I just did the caps, works fine...
The gnd pins of the smd elect caps take a lot heat. I ended up using two pencil irons simultaneously like hot tweezers,
to take them off quick.

Texas Hybrid batteries:
"From Post #3 the regulator chip is an Infineon TLE4278G 5V Low Drop Fixed Voltage Regulator. Link
From Post #46 the upgraded 16V 220uF Cap that Toyota is using is a Nichicon UUD series. Link (Thank you Ben Edwards)
From Post #34 the other 2 Caps are 35V 10uF and 330uF, you can choose which ever brand you like but we use Panasonics.
10uF Link. 330uF Link."

 

I also would like to thank Matt at Texas Hybrid for offering this important service at a very fair price:

- the replacement CM he sent me was in perfect condition and looked like a new part
- the soldering quality for the surface mount capacitors is indistinguishable from the soldering on the original CM. The one capacitor which was 100 uF in the original board was upgraded to 220 uF on the replacement CM
- all solder joints for the through hole parts are perfect and covered with a clear coating to prevent oxidation
- the odometer reading was set as I requested
- 2-day USPS Priority shipping in both directions included in the price
- fast credit issued to my PayPal account upon his receipt of my failed CM
- lifetime warranty

 

I read a bunch of good information here. I bought a 2007 Prius with 40k miles a month ago. I believe the reason why the retired people sold it is because of the start failing CM plus the 12V battery. So far, I love the car with its issues. After I replaced the 12V battery, the random failing CM went dead. I've bought a 2004 CM and swapped my CM ( plus the side signal light << the 2004 and 2007 are not supposed to be compatible: there is no tire pressure sensor for example). I did a reset on the maintenance light, a re-calibration of the fuel tank sensor and so far, except the mileage going from 40k to 123k, every thing is working good ( maybe except the fuel gauge that shows empty when I'm in the low 1/4 tank). This is winter and I don't want to mess up with the plastic in the car. I will start playing with my own CM and try to find what is in its guts. From the reading, about ROHS, and through components capacitors, the trick here is to cut the wire when you can and remove one side at a time. second option is using lead soldering wire. I know it is not eco but for the tiny quantity compare to your 12v battery... I'm in the middle of other projects but will spend time before the end of the year. I have oscilloscope and some tools but not a capacitance-meter. I'm commuting between Atlanta and N Florida, just in case someone is also interested to share experience

 

For $150, make life easy. Contact Matt at Texas Hybrid Batteries: solid reputation. NO fleeBay seller. NO scamList.org poster.

 

I hear you Exstudent. My background is electronic and RF engineer. I've repaired TV, digital camera, I've switched TFT connectors on LCDs. All the CAN, modbus, jbus are not scaring me. I just want to learn and sure, I will send it to Matt if too busy. thank you for the advice.

 

Alright guys, can someone post the non-nerd answer to what parts from Mouser are required to fix this issue? I love AND hate PriusChat because a lot of guys will get into the weeds for an issue and find really good solutions, but you have to read several pages of it and extract the nuggets from it while a few nerds argue about which part works best, and then once they sort of agree on that, they'll argue about which repair process works best. Some of these nerds come from extremely technical backgrounds where they would only attempt the repair using their professional several thousand dollar setup and aerospace industry training, and others have been able to do so with the bare minimum tools using experience they've accumulated over the years.

TL;DR: what are the damn Mouser part numbers and can I do this repair with good soldering skills and an iron/desoldering braid/solder?

 

See post 71 and buy the three surface mount capacitors. If you have experience soldering surface mount components then no worries. If you don’t, this is not a good starter project.

 

You are a true American Hero.

 

From Post #3 the regulator chip is an Infineon TLE4278G 5V Low Drop Fixed Voltage Regulator.
From Post #46 the upgraded 16V 220uF Cap that Toyota is using is a Nichicon UUD series. (Thank you Ben Edwards)
From Post #34 the other 2 Caps are 35V 10uF and 330uF, you can choose which ever brand you like but we use Panasonics.
10uF . 330uF.
from another web, there is also a mention of the epitaxial power transistor NEC c4552.
I did not find the reference on Mouser. >> I can't post link yet