Replaced Combination Meter at 195,000 km

[lucky1]

Starting at about 150,000 km I would start my Prius taxi up in the morning and have nothing showing on the dash for the speed and fuel gauge. I would solve the problem by disconnecting the negative connection on the battery and reconnecting. This problem would happen once every 2 weeks or so. Recently it was almost every day I would have to disconnect the battery.
I had to replace the combination meter to solve the problem. Cost me around $700 for parts and labor.
There are 12 Prius taxi's on our fleet and this is the 6th one to develop this problem. All around 150-200,000 km.

The parts guys at the local Toyota dealer tell me that it is only for our taxi's that they have had to order this part in.
Between the Motorola Radio and the Mentor Computer (gps system we receive our calls on) and my security camera we have a lot of extra stuff wired in to the taxi's.

Has anyone heard of the combination meter being a problem with the Prius or am I correct being suspicious about all our equipment being the problem.
Our mechanics do all the wiring and that alone makes me nervous.

Appreciate any input

[Patrick Wong]

Here's another string relating to Prius taxi and non-taxi failures (see posts #1 and #13):
Instrument Panel Problem (with video!!!)

I wouldn't blame your mechanics for causing the fault since the problem has been noted elsewhere. However it's unclear what is the root cause of the problem.

[lucky1]

Thanks for the info Patrick--- Looks like I will be replacing the combination meter every 18 months. Cutting into my fuel savings!

[brick]

That's bizarre. Has anyone taken a crack at diagnosing a busted cluster? Some of our electronics-savvy members were able to trace the early MFD failures to the root cause. (Something to do with a bad solder joint IIRC.)

[lucky1]

Brick- not sure if anyone has. Sure would be nice to know what is causing the problem.
My other Prius taxi acts up about once a month, it loses the speedometer for a short period (usually less than 20 min) and then comes back and won't act up for a month or two.

[northwichita]

150,000 km converts to close to 100k miles which is not that much in my opinion. The number of taxes involved (6 of 12- 50%) I would think the problem is related to the added equipment.
Assuming the wiring is added to dash wiring , I would ask the mechanics to wire the extra equipment differently.

There is a lot of information on the link Patrick provided, concerning the fuses etc which should be helpful.

[BAllanJ]

I wouldn't have thought a connection to the combination meter would be required for the taxi meter, since kms driven is available at the OBD port (since my scangauge knows), I thought they could use that... or since the taxi meter has gps, couldn't they use the gps idea of km driven? Maybe not since the taxi regs were probably written before that was available.

[lucky1]

Funny thing is that since I replaced the Combo meter the car is showing better gas mileage than it did throughout the summer. In the summer of 2008 it was normal for me to end a shift and see that I had used 4.5 to 4.8 litres per 100km. The car was in an accident last January. This summer it seemed that it was normal to end up the shift at 5.2 to 5.5 litres. I assumed that when the car was fixed that maybe it was not as aerodynamic as before and that it had changed the cars performance.
Today it was -1 celcius this morning and I haven't blocked the grill yet. I ended up the shift today at 4.7 litres per 100km. Same thing on Friday.
The car had been acting up for around 50,000 km before it got to the point where I had to change the combo meter because it was every day I had the problem.
I assume my fuel consumption hasn't changed and I was getting a false reading when I was seeing 5.2 to 5.5 while my combo meter was acting up.
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My other Prius has twice now lost the kph reading etc. on the dash but gets it back in about 15 min. This has been over 3 months. This car was also in an accident last winter and had $13,000 damage. Once again when I never seemed to do better than 5.2 litres per 100 km this summer I assumed it was because of the accident and major damage. I drove this car this morning for about 180 km and was 5.3 litres.I have the grill blocked on this car. I later drove the other Prius (with no grill block)that had the combo meter replaced, for 120 km and ended up at 4.7 litres burned per 100 km.
It has me scratching my head as to why the Black Prius with the new combo meter appears to be getting better fuel economy than it did on the hot summer days.
It is also performing better than the grey car that has the grill blocked and seems to be at the start of the problems that will cause me to have to replace the combo meter.

[lucky1]

After checking all the links to other posts about this problem I have noticed that almost everyone that has to replace the combination meter live in a cold climate. My problem that would occur every couple of weeks all of a sudden started acting up every day once the mornings started to get down to just below freezing.
I got tired of having to disconnect and reconnect the negative terminal on the 12v battery every morning so I replaced the combination meter.

I would assume that Toyota knows about this problem and hopefully will correct it before I replace my Prius taxi's in a couple of years.

[lucky1]

Just sent an email to one of the people who was hired by Toyota many years ago to build the hybrid engine for them. He has told me a couple of times to email him with questions about the motor. Going to see if he can get me any answers about whether or not Toyota is working to solve the Combination meter problem.
Better chance of getting an answer out of him than trying to contact Toyota and get an answer.