C1097

Code

Generic C — Chassis

ABS Hydraulic Pump Motor Circuit Short To Ground

Brand: Generic

Type: C — Chassis

Views: UK: 23 EN: 48 RU: 24

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Page language: EN

Causes

Damaged or chafed wiring harness (insulation worn through) with conductor contacting chassis ground
Corroded or damaged pump motor connector or terminal making a low-resistance path to ground
Internal short inside the pump motor windings to motor housing (ground)
Shorted driver transistor or output stage inside the ABS control module
Incorrect or damaged aftermarket electrical equipment tied into ABS wiring
Blown fuse or failed relay causing abnormal circuit behavior (may be related)

Symptoms

ABS warning lamp illuminated on dash
Possible loss of ABS function (braking behaves like non-ABS during hard stops)
Unusual pump or relay noise (may not run) or pump not activating when commanded
Other stability/traction warnings may be present depending on vehicle

What to check

Read and record all ABS/traction codes and freeze frame data with a suitable scan tool
Visual inspection of pump motor wiring, connectors, and ABS module connector for damage or corrosion
Check related fuse(s) and ABS pump relay for correct operation
Measure battery voltage at rest and with ignition ON to ensure proper supply
With ignition OFF, check for continuity between pump motor positive feed and chassis ground (expect open/high resistance)
Backprobe pump motor connector with a DVOM or current clamp while commanding pump ON via scan tool to observe voltage and current

Signal parameters

Battery supply voltage at pump feed (ign ON): approx. 12.0–13.0 V (varies with battery/charging)
When ABS pump is commanded ON: feed voltage should be ~battery voltage or a PWM duty signal depending on design
Pump motor winding resistance (disconnected): typically low ohms (vehicle-specific); should not be near 0 Ω (short) or infinite Ω (open)
Running current: several amps (often in the single-digit to low double-digit amp range); excessive current indicates internal short
No continuous low resistance to chassis ground on feed circuit when motor disconnected (DVOM should read high/open)

Diagnostic algorithm

Connect a scan tool, record codes and freeze frame, and attempt to actuate the ABS pump using a bi-directional control if available.
Perform a thorough visual inspection of the harness, pump motor connector, and ABS module connector. Look for pin damage, corrosion, crushed wires, or recent repair splices.
Verify fuses and relay operation for the ABS pump circuit. Replace if faulty and retest.
With ignition OFF, disconnect the pump motor connector. Measure resistance between the pump feed terminal and chassis ground. A low reading indicates a short in the motor or harness.
Check continuity between the ABS module output pin and the pump motor connector pin. Repair any low/shorted wiring found. Wiggle test the harness while monitoring continuity/voltage to find intermittent faults.
With the pump disconnected, command the pump ON via scan tool and measure voltage at the module output pin. If the output is shorted to ground at the module, suspect module output driver failure.
If pump motor shows low resistance to ground when disconnected, bench-test or replace the pump motor. If wiring checks good and module output is correct, replace pump motor.
If wiring and pump test OK but output is shorted at the module, replace or repair the ABS control module per manufacturer procedures.
After repairs, clear codes, perform ABS pump activation tests, and road test to confirm normal ABS operation.
Safety note: isolate battery power before performing connector repairs or when replacing modules. Follow vehicle manufacturer safety procedures.

Likely causes

Wiring abrasion where the harness crosses pinch points or near suspension/engine components
Corroded connector pins at the pump motor or ABS module (water ingress)
Pump motor internal failure producing low resistance to housing ground
Failed ABS module output driver causing apparent short on feed circuit