I got a new (used) prius a couple weeks ago. Apparently sold by a weasle. It's never started reliably, and the red triangle light comes on / off. Jumping it would start it though. I replaced the low voltage battery. It started 4 more times, then won't start at all. Not even with a jump. Also, the red triangle + CEL, and several other dash lights stayed on now.

The toyota dealer gave me a very vague diagnosis.

I was told 2 parts and 5 hours labor. Part 1: Hybrid Battery Computer - ECU - Computer Assembly, Battery - $960

Part 2: Hybrid Computer - ECU Computer, Hybrid Vehicle - $544

Labor - 5 Hours @$130 / HR

I'd really like to get some feedback before I spend $2500. Honestly, after like 2 hours on the web, I can't even figure out what the parts are that they need replacing.

I'm skeptical that these both actually need to be replaced. And even so at 5 hours, for 2 jobs, it's probably something I can DIY with some direction.

My standard cose reader doesn't show any code, so I figure the CEL is something with the hybrid system.

Below are screenshots from the written estimate.

EstimateDesc Estimate

  • Not hard to replace the parts but you may have trouble programming them unless you have and are familiar with techstream. If you try and replace with used ones the your dealer may refuse to program them. Have you called around to any independent shops? Tell them your looking on cost to replace BCM and HV Control and Hybrid Batter ECU. 2500 sounds a bit steep.
    – narkeleptk
    Commented Apr 3, 2020 at 14:08

1 Answer 1


Turns out, I just swapped the hybrid batter computer with a used one. No programming necessary. And no need to swap the computer up front. I read around, and the DIY crowd seemed to indicate that's pretty common. Just make sure the model number on the new part is compatible based on your vin.

The only problem is my wiring harness connector was fried where it hit the computer so I had to swap that. Took buying linesman gloves since it requires opening up and wiring to the hybrid battery. Not the most DIY friendly. Just easy wrench and bolts, but you gotta be careful with the electricity.

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