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abs main fuse

Discussion in 'Gen II Prius Care, Maintenance and Troubleshooting' started by jsrichjr, Jan 11, 2012.

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  1. jsrichjr

    jsrichjr Junior Member

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    My 2005 prius with 166500 miles has these lights on dash, (!) BRAKE and ABS, and there is a high pitch alarm, also brake pedal is hard and brakes don't work as well as they did just before warnings came on. Toyota dealer says the abs main fuse is blown. $300+ to replace main fuse. Service rep says he cant be sure the new fuse wont blow. He says complete abs system diagnosis could cost as much as $700. Anyone heard of this problem and have any advice? Thanks.
  2. seilerts

    seilerts Battery Curmudgeon

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    Any history of accidents or other electrical problems/repairs on this car? Did it happen during a rainstorm or in the car wash?

    There are many fuses that feed the ABS system. The risk here is that the brake actuator is dead and will just blow the fuse again. I'm not sure which fuse or relay that they mean to have a $300 repair quote.
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  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The 30A ABS-2 fuse is part of Unit A within the main relay/fuse box near the inverter. Unit A is the collection of fusible links, hence the $300 cost to remove that and replace. That price is relatively reasonable given dealer labor rates.

    The ABS-2 fusible link provides power to the ABS MTR 2 relay, which then provides power to the brake actuator assembly.

    I would suggest that 1) the dealer should assign the best Prius tech to this and that 2) the tech should use a digital multimeter to measure the resistance from the ABS MTR 2 relay switched contacts to ground. With the ABS-2 fusible link open, the resistance will be infinite at one switched contact. The other switched contact will measure a low resistance, but it should be at least 0.5 ohms or so. If it is lower, then the fusible link will blow again and the brake actuator will need to be replaced.

    Of course, this particular measurement will take around 2 minutes and is not worth paying $700 for.
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  4. northwichita

    northwichita .

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    $700 just to diagnosis the problem? Time to find another mechanic in my opinion.
    I looked up your other posts, you bought the car new, used as a rural mail vehicle, now has 166k, that is a lot! of stops ( I also deliver mail with my prius).
    My brake actuator is making that ratcheting sound for longer periods of time, lately I counted out 15 sec of clicking when I get into the car in the morning. I think mine may soon hit the dust.

    For what its worth, I would replace the fuse and brake actuator with salvage parts, then find someone to bleed the brake system.
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  5. jsrichjr

    jsrichjr Junior Member

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    Thanks for the info. Probably should have mentioned that I use it on a mail route (600 stops/day) That ratcheting noise is louder and longer than it used to be as northwichita said. Thanks again. This is a great site. Very helpful.
  6. seilerts

    seilerts Battery Curmudgeon

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    A full brake fluid drain, fill, and bleed is probably in order. It's worth a shot, given the time and money for the repair that it could prevent.

    A mail carrier's car is about the worst case scenario for the hydraulic brake system. jsrichjr, meet northwichita. You two should start a club.
    2 people like this.
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