If your scan tool displays C0274, your vehicle’s Electronic Brake Control Module (EBCM) has detected a short to ground in the ABS delivery solenoid circuit inside the Hydraulic Control Unit (HCU).
The ABS delivery solenoid—also known as the isolation solenoid—controls hydraulic brake pressure during anti-lock braking events. When the EBCM senses that a wheel is beginning to lock, it energizes the delivery solenoid to isolate brake pressure while the return solenoid and ABS pump motor regulate pressure. If the EBCM detects that the delivery solenoid circuit has become shorted to ground, it stores C0274 and usually disables the Anti-lock Braking System (ABS), Traction Control (TCS), and Electronic Stability Control (ESC/StabiliTrak) to prevent further electrical damage.
Unlike C0273, which indicates an open circuit, C0274 means the delivery solenoid circuit has an unintended connection to ground, causing improper current flow and preventing normal ABS operation.
For additional chassis diagnostics and repair guides, visit our Complete OBD-II Trouble Code Guide:
https://my.prostreetonline.com/dtc-obdii
Quick Facts
| Item | Information |
|---|---|
| OBD-II Code | C0274 |
| Description | ABS Delivery Solenoid Circuit Short to Ground |
| Category | Chassis (C) Codes |
| System | Anti-lock Braking System (ABS) |
| Severity | ★★★★☆ High |
| Safe to Drive? | Yes, but ABS and stability systems will likely be disabled |
| Common Causes | Shorted wiring, internally shorted delivery solenoid, damaged connectors, Hydraulic Control Unit failure, faulty EBCM |
| Typical Repair Cost | $100–2,000 |
What Does C0274 Mean?
The C0274 code indicates the Electronic Brake Control Module has detected that the ABS delivery (isolation) solenoid circuit is shorted directly to ground.
Normally, the EBCM controls current flow through the delivery solenoid to precisely regulate hydraulic brake pressure. If the circuit unintentionally contacts the vehicle chassis or another grounded conductor, current bypasses its intended path, preventing the solenoid from operating correctly.
The EBCM continuously monitors:
- Circuit voltage
- Current flow
- Solenoid resistance
- Driver output
- Commanded versus actual operation
If the circuit voltage drops unexpectedly because of a short to ground, the EBCM stores C0274 and disables ABS-related functions.
Symptoms of C0274
Drivers may notice:
- ABS warning light illuminated
- Traction Control warning light
- Electronic Stability Control warning
- Service Brake System message
- Service StabiliTrak message (GM vehicles)
- ABS disabled
- Traction Control unavailable
- Stability control disabled
- Stored C0274 diagnostic code
The vehicle’s standard hydraulic braking system typically continues to function normally.
Common Causes
Chafed or Damaged Wiring
The most common cause is wiring that has rubbed against:
- Frame rails
- Suspension components
- Brake lines
- Engine components
Eventually the insulation wears through, allowing the wire to contact ground.
Internally Shorted Delivery Solenoid
The delivery solenoid coil can fail internally, creating a direct short to ground.
Melted Wiring Harness
Excessive engine or exhaust heat may melt wire insulation, allowing adjacent conductors or chassis metal to create a ground fault.
Water Intrusion
Moisture inside connectors or the Hydraulic Control Unit can create conductive paths that short the circuit.
Damaged Electrical Connectors
Inspect connectors for:
- Bent terminals
- Corrosion
- Moisture
- Broken locking tabs
Hydraulic Control Unit Failure
Since the delivery solenoid is integrated into the Hydraulic Control Unit on many vehicles, an internal short often requires replacement of the HCU.
Faulty Electronic Brake Control Module
Although uncommon, an internal EBCM failure can falsely detect or create a short-to-ground condition.
How Serious Is C0274?
High.
When C0274 is present, the Electronic Brake Control Module generally disables:
- Anti-lock Braking System
- Traction Control
- Electronic Stability Control
- Brake Assist
The vehicle can still be driven, but emergency braking performance is significantly reduced.
Can You Drive With C0274?
Yes—but with caution.
Normal hydraulic braking usually remains available.
However:
- Wheels may lock during emergency braking.
- Steering control under heavy braking is reduced.
- Traction control becomes unavailable.
- Stability control cannot correct skids.
Repairs should be completed as soon as possible.
How to Diagnose C0274
1. Scan the ABS Module
Use a professional scan tool capable of reading manufacturer-specific ABS codes.
Look for related codes including:
- C0271
- C0272
- C0273
- C0275
- C0265
- U-series communication codes
2. Inspect Battery and Charging System
Verify:
- Battery voltage
- Charging voltage
- Ground integrity
Electrical system problems can complicate ABS diagnosis.
3. Inspect Wiring Harness
Carefully inspect wiring for:
- Chafed insulation
- Melted wiring
- Pinched harnesses
- Rodent damage
- Contact with sharp metal edges
Pay close attention near suspension components and frame rails.
4. Check for Short to Ground
Using a digital multimeter:
- Disconnect the EBCM connector.
- Disconnect the Hydraulic Control Unit connector if applicable.
- Measure continuity between the delivery solenoid circuit and chassis ground.
Continuity where none should exist confirms a short to ground.
5. Measure Delivery Solenoid Resistance
Compare measured resistance with manufacturer specifications.
Very low resistance often indicates an internally shorted solenoid.
6. Perform Active Solenoid Testing
Many professional scan tools allow technicians to command the delivery solenoid.
Verify:
- Solenoid activation
- Current draw
- Driver feedback
- Circuit operation
Failure to activate combined with a confirmed short typically identifies the fault.
7. Inspect the Hydraulic Control Unit
If wiring tests good but the solenoid remains shorted, replacement of the Hydraulic Control Unit may be necessary.
Some vehicles allow separate replacement of the Electronic Brake Control Module, while others require replacement of the complete ABS hydraulic assembly.
Common Repairs
| Repair | Estimated Cost |
|---|---|
| Repair damaged wiring | $100–350 |
| Replace damaged connector | $75–200 |
| Repair ground fault | $75–200 |
| Replace Hydraulic Control Unit | $700–1,800 |
| Replace Electronic Brake Control Module | $800–2,000 |
| Module programming | $100–250 |
Common Diagnostic Mistakes
Technicians commonly:
- Replace wheel speed sensors unnecessarily.
- Replace the Hydraulic Control Unit before checking the wiring harness.
- Overlook chafed wiring near suspension components.
- Fail to perform resistance testing.
- Ignore moisture inside electrical connectors.
- Skip continuity testing to ground.
Vehicles Commonly Affected
C0274 is commonly reported on:
- Chevrolet Silverado
- GMC Sierra
- Chevrolet Tahoe
- GMC Yukon
- Chevrolet Avalanche
- Chevrolet Suburban
- Cadillac Escalade
- Chevrolet Express
- GMC Savana
- Chevrolet TrailBlazer
- GMC Envoy
Similar short-to-ground delivery solenoid faults may also appear on other manufacturers equipped with Bosch ABS hydraulic control systems.
How to Prevent C0274
Reduce the likelihood of C0274 by:
- Inspecting ABS wiring during brake service.
- Securing loose wiring harnesses.
- Keeping electrical connectors clean and dry.
- Repairing damaged insulation immediately.
- Preventing moisture intrusion.
- Addressing ABS warning lights promptly.
Frequently Asked Questions
What causes C0274?
The most common causes include chafed wiring, internally shorted delivery solenoid coils, damaged connectors, Hydraulic Control Unit failure, or an Electronic Brake Control Module fault.
Is C0274 serious?
Yes.
Although conventional braking remains functional, the loss of ABS, traction control, and stability control reduces vehicle safety during emergency braking.
Can damaged wiring cause C0274?
Absolutely.
A wire rubbing against the chassis is one of the most common causes of a short-to-ground condition.
Does C0274 mean the Hydraulic Control Unit is bad?
Not necessarily.
The wiring harness should always be inspected before replacing expensive ABS components.
Does C0274 affect engine performance?
No.
The code only affects the braking and chassis safety systems.
Final Thoughts
The C0274 code indicates a short-to-ground condition in the ABS delivery solenoid circuit, preventing the Electronic Brake Control Module from properly controlling hydraulic brake pressure during anti-lock braking events. While the vehicle’s standard braking system generally continues to operate, the loss of ABS, traction control, and stability control significantly reduces braking performance in emergency situations.
Most repairs involve locating damaged wiring, repairing ground faults, testing the delivery solenoid, and determining whether the Hydraulic Control Unit or Electronic Brake Control Module requires replacement. Performing thorough electrical testing before replacing major ABS components can prevent unnecessary repair costs.
For additional chassis diagnostics and repair guides, browse our complete Chassis (C) OBD-II Code Library:
- Complete OBD-II Code Guide: https://my.prostreetonline.com/dtc-obdii/
- (B) Code Library: https://my.prostreetonline.com/dtc-doctor/b-code-obd-ii-codes/
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