SO, I run a taxi cab co in Berkeley, Ca, one of our prius 05 fleet is acting up as some times the car will start up and run perfectly but the dash meter will be totally dark, Since this is a taxi cab vehicle, the taxi meter is connected with the odometer(the taxi meter reads the odometer to calculate the taxi fare), if the odometer is not working the taxi meter(Taxi fare meter ) will not work as well, meaning the driver will not make any money, the meter will show only the base price $3.50 no matter how many miles he drives the passenger. most of the time in this situation, the car becomes stubborn to shut off and have to use the safety override (holding the power button for 3 seconds to shut it off). And then the problem will be fixed on its own after over night rest. I have also figured that problem can be fixed temporary by resetting the on board computer system, meaning disconnection the auxiliary battery. My question is, is this a good practice resetting the car so frequently, will it lead to bigger problem?
I don’t think resetting will really do any harm. But ecu will learn characteristics of engine and forget them when resetting. So resetting will increase your fuel consumption. But you could probably get that combination meter replaced for free. Combination Meter Warranty Enhancement | Page 8 | PriusChat
What's the condition of the 12v? I trust you'll have checked the connections from the speed sensor to the meter to make sure it's getting the pulse? What's the history of the driver? Is he trusted or has he been tinkering with the meter and messed it up?
If car is less than 9 years old should qualify for free combination meter replacement, talk to the dealer. If you have to pay out of pocket, the part can be purchased form RockAuto.com for about $200, they need VIN, odo reading + $300 core charge (you get back when you send them the old one). Arrives in a few days after ordering. Takes an experienced tech about 60-90 minutes to replace. Doing it the first time might take longer (entire dash top has to come out). Kensington Garage in the Berkeley hills is a nice Prius friendly shop if you want a shop to do it.
Part number for 06-09 Prius is Dorman 599551 but they should still be covered by Toyota dealer for free. (9 years from when car entered service)
I work on taxis, this is a common problem due to the fact that taxis run 24/7 most of the time, your instrument cluster is going bad and will either need to be replaced or rebuilt, due to the many hours the speedo/cluster is on it's showing wear, the current Prius I have has 150k miles on it due to an instrument cluster replacement last recorded mileage was 214k miles early this year. A "trick" just to get the cluster to work is to disconnect & reconnect the speedo plug (square white plug) which is located behind the round power on switch. If you decide to replace the cluster you will need either yrs 2004 or 2005.
I have found a way to get the cluster to come on. It may sound crazy but it works more often than not. When you get into the car leave the door open, put the key in, place foot on the brake, and then press the power button and turn the headlights on at the same time. Weird but it works most of the time. Any comments please post. Thanks
ALL Years of Gen 2 are interchangeable. I just replaced a 2004 with a 2009. You must replace both of the matching combination meter and light cluster circuit boards most easily found as an assembly (20"+ long, of many plastic parts and the two matching circuit boards) from salvage. Not having tires with TPMS I now wish I would have removed the TPMS LED light from it's circuit board by simply breaking it off the circuit board. The reboot & start failed as before UNTIL I SET the PARKING BRAKE. From then forward dash instruments worked fine. See this post. Combination Meters that stop at 299,999 miles, Who's affected and what you can do about it. | PriusChat
