What Does C1186 Mean?
The ABS power relay output circuit is open, meaning there is a complete break in the circuit that delivers power from the relay to the ABS hydraulic pump or module. The ABS system is non-functional because the pump motor cannot receive power to modulate brake pressure. ABS, traction control, and stability control warning lights will all be illuminated.
Safety Warning
ABS is fully disabled. The hydraulic pump cannot run, so the system cannot modulate brake pressure. Conventional brakes still function normally. Exercise extra caution on wet or icy roads and during emergency stops. Have repaired as soon as possible.
Common Causes
35%
Broken or corroded wire between the ABS relay output and the ABS hydraulic unit
25%
ABS power relay with internally open contact (contacts not closing)
20%
Loose or corroded connection at the ABS hydraulic unit power input
15%
Fusible link between the relay and ABS unit burned open
5%
Corroded fuse box relay socket causing high resistance or open circuit
Diagnostic Steps
1
With the ABS power relay installed, command the ABS pump to run via the scan tool's ABS actuator test. Measure voltage at the ABS hydraulic unit power input connector. If 0V, the circuit is open between the relay and the unit.
2
Remove the relay and jumper pins 30 to 87 in the relay socket briefly. If the ABS pump runs, the relay is faulty — replace it. If the pump still does not run, the open is in the wiring or at the pump.
3
Check for a fusible link in the ABS power supply wire between the fuse box and the ABS unit. These can burn open invisibly inside their insulation — gently tug on the wire and flex it to check for a hidden break.
4
Inspect the ABS hydraulic unit power connector for corrosion, pushed-back pins, or heat damage. Clean and reseat the connector.
5
Trace the power wire from the relay socket to the ABS unit, checking for breaks, cuts, or rodent damage along the entire length.
Estimated Repair Cost
$30 - $400
Parts + labor, varies by vehicle and location
The ABS power relay output circuit is open, meaning there is a complete break in the circuit that delivers power from the relay to the ABS hydraulic pump or module. The ABS system is non-functional because the pump motor cannot receive power to modulate brake pressure. ABS, traction control, and sta...
The most common cause of C1186 (ABS Power Relay Output Open Circuit) is: Broken or corroded wire between the ABS relay output and the ABS hydraulic unit
Typical repair costs for C1186 range from $30 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
ABS is fully disabled. The hydraulic pump cannot run, so the system cannot modulate brake pressure. Conventional brakes still function normally. Exercise extra caution on wet or icy roads and during emergency stops. Have repaired as soon as possible.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1186 to identify the root cause.
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Quick Info
Category
Chassis
System
ABS / Traction Control
Difficulty
Type
Manufacturer
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