P0877

Code

Generic P — Powertrain

Transmission Fluid Pressure Sensor/Switch D Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 20 EN: 39 RU: 37

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Page language: EN

Causes

Damaged or shorted wiring in sensor D circuit (short to ground)
Poor or corroded connector or terminal at the sensor or harness
Failed transmission fluid pressure sensor/switch D
Low or missing reference voltage from PCM/TCM
Intermittent circuit connection due to vibration or damaged insulation
PCM/TCM input fault or internal short (less common)

Symptoms

Check Engine/Transmission warning lamp (MIL) illuminated
Transmission may go into limp or fail-safe mode
Harsh, delayed, or incorrect shifting
Stored transmission-related trouble codes
Possible abnormal transmission line/noise or inability to shift into certain gears

What to check

Retrieve freeze frame and live data with a scan tool; note conditions when code set
Visually inspect sensor D connector, pins and harness for corrosion, damage or moisture
Check transmission fluid level and condition; correct if low/contaminated before further tests
Backprobe sensor connector and measure reference voltage, signal voltage and ground with scan tool or multimeter
Perform wiggle test on harness while monitoring signal for intermittent change
Check continuity and resistance of wiring to the PCM/TCM and to ground

Signal parameters

Typical pressure sensor uses PCM reference (≈5 V) and provides an analog output 0–5 V proportional to pressure (varies by manufacturer)
Circuit low condition: sensor output near 0 V or significantly below expected range for given operating condition (often
Expected behavior: output voltage should change in response to transmission pressure changes (voltage rises with increasing pressure)
Reference and ground should be stable (reference ≈5 V, ground ≈0 V); significant deviation suggests wiring/PCM issue

Diagnostic algorithm

Read and record freeze-frame data and live sensor D voltage with a scan tool. Confirm P0877 is active and note operating conditions when set.
Visually inspect sensor D connector and harness for damage, corrosion, pushed-out pins, or water ingress. Repair any issues.
Check transmission fluid level and condition; top or change fluid if required and clear codes to see if it returns.
With ignition ON (engine off), backprobe sensor connector: verify reference voltage (≈5 V) from PCM and good ground. If reference or ground missing, trace and repair wiring to PCM/ground.
Measure sensor output voltage with engine running and transmission in required state. Verify voltage changes with throttle/pressure changes. If output remains near 0 V (circuit low), suspect sensor or short to ground.
Check continuity between sensor signal wire and PCM input. Check for shorts to ground using an ohmmeter. Repair damaged wires or insulation.
If wiring and connectors are good, substitute a known-good pressure sensor D (if available) or bench-test the sensor per manufacturer procedure. Replace sensor if it fails output tests.
If new sensor and wiring are good but code persists, inspect PCM/TCM input circuit for internal fault or seek module bench testing/programmable reflash from dealer/qualified shop.
After repairs, clear codes and perform a road test / operating cycle while monitoring live data to ensure proper sensor response and no return of P0877.

Likely causes

Corroded/loose connector at the pressure sensor D
Frayed harness with exposed conductor contacting vehicle ground
Failed pressure sensor D (internal electronics)
Broken ground or poor PCM/TCM ground connection

Fault status

⚠️ Status

Transmission Fluid Pressure Sensor/Switch D Circuit Low — low or missing signal detected on transmission pressure sensor D circuit; inspect sensor, wiring, connectors, grounds, and PCM input.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 3.0 hours