P0752

Code

MERCEDES-BENZ P — Powertrain

Shift Solenoid A Stuck On

Brand: MERCEDES-BENZ

Type: P — Powertrain

Views: UK: 22 EN: 30 RU: 39

AI status

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Page language: EN

Causes

Shorted solenoid coil to battery voltage
Stuck or mechanically seized shift valve/solenoid
Contaminated transmission fluid or clogged valve body
Damaged wiring harness or poor connector contact
Faulty shift solenoid assembly
Faulty transmission control module (less common)

Symptoms

Transmission stuck in a single gear (limp/home mode)
Harsh or delayed shifting
Failure to shift into certain gears
Check Engine / Transmission warning light illuminated
Poor acceleration or unusual transmission behavior

What to check

Read and record all transmission-related DTCs and freeze frame data with a capable scan tool
Check transmission fluid level and condition (color, smell, debris)
Visually inspect wiring, pins and connectors at the valve body and TCM for damage or corrosion
Monitor live data: solenoid A command vs actual status (if supported)
Measure solenoid coil resistance at the connector (compare to OEM spec)
Backprobe solenoid connector to check for constant battery voltage or grounding when not commanded

Signal parameters

Solenoid coil resistance: typically consult OEM spec (commonly ~10–40 Ω depending on design)
Command voltage: switched +12 V or pulsed ground depending on system (use scan tool/oscilloscope to confirm)
Expected behavior: solenoid should be de-energized with no command and show open/low duty. When commanded ON it should show pulsed or steady drive per TCM strategy
No continuous battery voltage or continuous ground on the solenoid circuit when TCM is not commanding

Diagnostic algorithm

Connect a factory-level scan tool, read and save codes and freeze frame. Clear codes and attempt to reproduce to confirm persistence.
Check transmission fluid level and condition. If fluid is severely contaminated or burnt, consider fluid service and further diagnosis.
Visually inspect the wiring harness, connectors, and pin terminals for damage, corrosion, bent pins, or signs of overheating at the valve body and TCM.
With ignition on, backprobe the solenoid A connector and observe voltage while commanding solenoid ON/OFF with the scan tool. Note if the circuit is constantly hot or grounded regardless of command.
Remove connector and measure coil resistance between solenoid pins with the harness disconnected. Compare to OEM spec. If open or shorted, replace solenoid.
If resistance appears normal but circuit shows constant voltage or ground, perform wiring tests: check for shorts to battery or ground, wiggle test harness, and inspect continuity to TCM.
If wiring and connectors are good, remove valve body or access solenoid to bench-test operation and inspect for contamination or mechanical sticking. Replace solenoid or valve body components as required.
If all transmission-side components test good, evaluate the TCM outputs and grounds; substitute or bench-test TCM only after exhausting mechanical and wiring causes.
After repair, clear codes and perform functional road test and confirm normal shift operation and no return of P0752.

Likely causes

Short to power in solenoid A circuit (pin-to-power)
Corroded/loose connector at solenoid or valve body
Failed solenoid coil internally shorted
Valve body contamination causing sticking
Low/overheated transmission fluid causing solenoid/valve malfunction

Fault status

⚠️ Status

P0752 — Shift Solenoid A Stuck On: TCM detected Solenoid A circuit continuously energized or valve stuck ON. Causes include short to power, failed solenoid, stuck valve, contaminated fluid, or wiring/connector fault.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5 - 4.0 hours

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