ABS codes?

Tiny
BHAMDOC1973
  • MEMBER
  • 2008 LEXUS LS 460
  • V8
  • 2WD
  • AUTOMATIC
  • 160,000 MILES
Friend's car has these codes. It also has a brake light switch code but I don't see anything broken on the switch. It is intermittent comes and goes. I have never encountered this relay code, any advice?
Sunday, October 9th, 2022 AT 7:16 PM

4 Replies

Tiny
STEVE W.
  • MECHANIC
  • 13,577 POSTS
Okay, you show codes C1253, and C1256. These could both be related to the brake switch issue. As such I would replace it first, then clear the codes and see if they return.
The reasoning is that the 1253 code is saying that the brake controller relay is on longer than it should be to generate the accumulator pressures programmed in. The 1256 code says that the accumulator pressures are lower than they should be and it's having trouble keeping up with the braking system. One of the causes of this could be excessive brake usage. That could mean that the bad brake switch is telling the accumulator to dump some pressure while at the same time the EBCM is saying the pressure is too low and turns the relay on. It would sort of be like you turning on the faucet and waiting for the sink to fill up, but the drain plug isn't in the drain.
As for the brake switch, there are multiple contacts and a potentiometer inside it to tell the EBCM the amount of braking and how hard as well as telling it to activate the brake lights. These systems are active even if the key is off, so it is possible the stroke sensor is telling the brakes to activate at night when the car is parked and constantly cycles the system.
I'll attach the removal of the sensor, to install the new one it's a reversal of that process except it will come with a pin securing it. You install the switch, then connect it to the brake lever and then step on the brake to fracture the pin, remove the broken pieces and plug it in.
Because of the way the system operates you need to disconnect the battery first.
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Sunday, October 9th, 2022 AT 9:42 PM
Tiny
BHAMDOC1973
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Thanks, yes, that makes sense. By a pin in the new sensor you mean a weak pin that can be broken by pressing the brake, similar to a pin in the belt tensioner? Just to keep the moving plastic piece from being exposed when sensor is new and shipped?
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Monday, October 10th, 2022 AT 6:14 AM
Tiny
STEVE W.
  • MECHANIC
  • 13,577 POSTS
Yep, the pin holds it in place so you can align the sensor, then it breaks as soon as you step on the pedal.
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Monday, October 10th, 2022 AT 6:27 AM
Tiny
BHAMDOC1973
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Smart.
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Monday, October 10th, 2022 AT 6:44 AM

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