C1252 on Toyota
Brake Booster Pump Motor on Time Abnormally Long
C1252 on Toyota vehicles indicates brake booster pump motor on time abnormally long. Au7o has documented this code across 4 Toyota models — most commonly on 4Runner, Camry, Highlander. Toyota/Lexus manufacturer-specific chassis code on models with a hydraulic (pump-and-accumulator) brake booster — that includes the Electronically Controlled Brake (ECB) system on hybrids like the Prius, but also non-hybrid trucks and SUVs such as the FJ Cruiser and 4Runner, where it lives in the vehicle stability control section. The skid control ECU drives the brake booster pump motor to charge the accumulator, and Toyota's factory detecting condition is simply that the motor operates for 3 minutes or more, which means the system cannot build or hold target pressure. Toyota's factory trouble areas are the brake booster pump assembly, the hydraulic brake booster (accumulator pressure sensor), and the master cylinder solenoid, which houses the pump motor relay and the skid control ECU. Expect brake and ABS warning lights, a warning buzzer, and a hard, high pedal with reduced power assist — treat this as a braking-performance fault, not a nuisance light. Typical repair costs on Toyota range from $1,200 to $3,500, depending on the specific model and root cause.
Common Causes of C1252
- •Worn or failing brake booster pump motor / brake booster pump assembly (Toyota's first listed trouble area)
- •Internal leak in the hydraulic brake booster or accumulator that stops it holding pressure (on hybrids this typically pairs with C1391, Accumulator Leak)
- •Faulty accumulator pressure sensor inside the hydraulic brake booster, so the ECU never sees target pressure
- •High resistance, damage, or loose screws in the pump motor wire harness (MT+/MT-) between the booster and the pump
- •Master cylinder solenoid / skid control ECU fault (the pump motor relay is built into it)
- •Companion codes C1253, C1254, or C1256 set at the same time — Toyota says to diagnose and repair those first
C1252 on Toyota by Model
Toyota 4Runner(2 issues)
- Brake Booster / Master Cylinder Internal Leak Causing Hard Pedal and Reduced Braking Assist2003-2009
Multiple 4th-generation 4Runner owners report the brake pedal becoming hard, requiring excessive effort to stop, often accompanied by ABS/VSC/TRAC warning lights and a buzzing or continuously running brake actuator. Toyota issued service information for brake booster pump/master cylinder concerns on related platforms, and owner complaints frequently describe internal accumulator or actuator failure rather than simple pad/rotor wear. Repairs are expensive because the booster/master/actuator assembly is typically replaced as a unit.
- ABS Actuator / Master Cylinder Assembly Failure Triggering ABS/VSC/TRAC Lights and Brake Pump Noise2003-2009
On 4th-gen 4Runners the integrated ABS actuator/brake master cylinder assembly (with electric pump motor and accumulator) fails internally. The pump motor or accumulator wears out so the pump never reaches pressure and runs continuously; owners get simultaneous ABS, BRAKE, VSC and TRAC warning lights, a loud continuous in-cabin alarm, electronic noise when braking, and a hard or sinking pedal with reduced assist. It is a safety-relevant failure and the assembly is one of the most expensive non-drivetrain parts on the truck. This is distinct from the brake booster/master-cylinder internal-leak issue: this is the ABS hydraulic actuator/accumulator unit.
Toyota Camry(1 issue)
- Camry Hybrid Brake-Booster Internal Leak - T-SB-0130-19 / CSP ZKK2012-2014
Toyota T-SB-0130-19 and Customer Support Program ZKK apply to certain 2012-2014 Camry Hybrid vehicles with brake, ABS and/or TRAC warning lights or a Check VSC message. Verification requires C1391, C1252, C1256 or C1253. Toyota attributes the specified condition to a small internal brake-fluid leak in the brake-booster assembly with master cylinder. Warning lamps can have other causes, and the documents do not support extending this record to gasoline Camrys or other model years. ZKK's primary coverage ended March 31, 2021; its secondary coverage was 10 years or 150,000 miles from first use, so its published coverage period has expired for this model-year range as of 2026.
Toyota Highlander(1 issue)
- Hybrid Brake Booster / ABS Actuator Assembly Failure (Accumulator Leak) — C13912006-2013
The regenerative-braking brake actuator (the integrated ABS/booster/accumulator pump module) is a known weak spot on the Highlander Hybrid. The accumulator develops an internal leak and the pump runs constantly, triggering a loud, repetitive whirring/buzzing and warning lights; in some cases brake assist is reduced, which owners describe as a serious safety concern (the same family of actuators drove early Prius brake recalls). CarComplaints documents repeated brake actuator complaints on the 2006 Highlander Hybrid, and the repair is rarely covered out of warranty.
Toyota Prius(1 issue)
- Brake Booster and Brake Booster Pump Assembly Internal Leak (DTC C1391)2010-2015
The electro-hydraulic brake booster/accumulator assembly on third-generation Prius develops an internal fluid leak, so the accumulator can no longer hold pressure. The pump then runs constantly to keep pressure up (loud buzzing/grinding from under the driver's footwell) and eventually the system sets C1391 (often with C1252, C1253 or C1256), turns on the brake, ABS and hybrid warning lights, and falls back to unassisted braking with a hard, long pedal and much longer stopping distances. Toyota acknowledged the failure with Customer Support Program ZJB covering 2010-2015 Prius and Prius PHV brake booster and brake booster pump assemblies (10 years/150,000 miles; primary coverage has now expired).
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View C1252 across all makes →Frequently Asked Questions
What does C1252 mean on Toyota?▼
C1252 stands for "Brake Booster Pump Motor on Time Abnormally Long." Toyota/Lexus manufacturer-specific chassis code on models with a hydraulic (pump-and-accumulator) brake booster — that includes the Electronically Controlled Brake (ECB) system on hybrids like the Prius, but also non-hybrid trucks and SUVs such as the FJ Cruiser and 4Runner, where it lives in the vehicle stability control section. The skid control ECU drives the brake booster pump motor to charge the accumulator, and Toyota's factory detecting condition is simply that the motor operates for 3 minutes or more, which means the system cannot build or hold target pressure. Toyota's factory trouble areas are the brake booster pump assembly, the hydraulic brake booster (accumulator pressure sensor), and the master cylinder solenoid, which houses the pump motor relay and the skid control ECU. Expect brake and ABS warning lights, a warning buzzer, and a hard, high pedal with reduced power assist — treat this as a braking-performance fault, not a nuisance light. On Toyota specifically, this code is documented across 4 models.
What causes C1252 on Toyota vehicles?▼
Common causes on Toyota: Worn or failing brake booster pump motor / brake booster pump assembly (Toyota's first listed trouble area), Internal leak in the hydraulic brake booster or accumulator that stops it holding pressure (on hybrids this typically pairs with C1391, Accumulator Leak), Faulty accumulator pressure sensor inside the hydraulic brake booster, so the ECU never sees target pressure, High resistance, damage, or loose screws in the pump motor wire harness (MT+/MT-) between the booster and the pump, Master cylinder solenoid / skid control ECU fault (the pump motor relay is built into it). Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix C1252 on a Toyota?▼
Repair costs on Toyota range from $1,200 to $3,500, depending on the specific model and root cause.
Which Toyota models have C1252 documented?▼
Au7o has documented C1252 on 4 Toyota models: 4Runner, Camry, Highlander, Prius.