After 18 years of daily usage, our 2005 Prius was starting to have issues with its gauge cluster. It seems to be a common issue, possibly related to an under-sized capacitor that eventually gets too weak. The car will still function, however the speedometer, odometer, gear indicator, fuel gauge, etc is all integrated into this one display. In this state it would not pass a California SMOG check, since the check engine light and warning lights would also not work.
There are services that will take your old circuit board, repair it, and send it back. Other services will take your VIN and mileage and send you a replacement programmed for the car. I went the DIY route instead, following the steps on priusnotworking.com.
Repair at your own risk! I’m posting my experience because I had fun doing it and the extra pictures may help someone else attempting the same thing.
The most annoying part is that most of the dash needs to be opened up to get this circuit board. Here is the before picture:
I wish I had turned the steering wheel the correct way around. It drives me a bit nuts looking at the pictures again. And here is the after:
This youtube video was a big help in step-by-step removing all the panels, disconnecting the passenger air bag, etc.
Next warning, I am not the best electronics repair person, however it got the job done and it’s been working for 6 months now. The problem capacitor is the small one in the middle labeled 100uf 16v.
My soldering iron was having issues, so had to revert to a soldering gun but it’s sufficient for large components like this. I used solder wick to remove the old solder and release the capacitor. Before installing the new capacitor, it’s a good idea to test that the new one for proper capacitance. My meter showed it as 220uf as expected.
My new capacitor is now soldered on. I was concerned about vibration over time, but the legs are soldered on such large pads I think it will be fine.
The dash was re-assembled, minus one of the dash trim pieces I broke, and it worked! There are several wire looms and plugs, so be careful and make sure all are plugged back in.
If any trim pieces broke during the dash removal, check ebay for a good used piece or an aftermarket replacement. I went with an aftermarket one, and while the glossiness of the piece wasn’t exactly the same, in an 18 year old car it’s fine and not noticeable from all the other wear and tear.
That’s it! I enjoyed doing the job, and besides breaking a trim piece it went smoothly with no extra screws or disconnected wire looms at the end.