P1757

Code

MAZDA P — Powertrain

Transmission Shift Solenoid B Circuit Shorted

Brand: MAZDA

Type: P — Powertrain

Views: UK: 30 EN: 49 RU: 38

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Page language: EN

Causes

Short to ground in the shift solenoid B wiring
Short to battery / power feed on the solenoid circuit
Failed shift solenoid B (internal short)
Damaged, corroded, or poorly connected solenoid connector
Chafed or pinched wiring harness contacting chassis or other conductors
Blown transmission-related fuse or relay causing abnormal voltage

Symptoms

Check Engine Light / Transmission warning light illuminated
Erratic or harsh shifting, or gear selection problems
Transmission stuck in limp/limitation mode (single gear)
Delayed engagement or failure to shift into certain gears
Possible no-go or limp-home behavior
Stored diagnostic trouble code P1757 (and sometimes additional transmission codes)

What to check

Read and record all stored codes and freeze-frame data with a scanner capable of Mazda transmission modules
Inspect harness and connector for shift solenoid B for corrosion, pin damage, melted insulation or exposed conductors
Visually follow the wiring from the solenoid connector toward the transmission and TCM for chafing or contact with metal
Check relevant fuses and relays for the transmission circuits
Measure DC resistance of the solenoid with connector disconnected (compare to spec)
Backprobe the solenoid connector and activate the solenoid (command ON) to observe voltage and signal behavior

Signal parameters

Typical solenoid DC resistance: approximately 10–40 ohms (varies by model) — consult vehicle spec
Shorted condition indicated by very low resistance (e.g.,
Open circuit indicated by infinite/OL resistance
Activation supply: battery voltage available at feed side (~12 V) while TCM switches ground (or vice versa depending on design)
Activated signal: pulsed/PWM from TCM; duty cycle varies with shift control strategy
Current draw when activated normally modest (hundreds of mA); abnormally high current suggests short or internal solenoid fault

Diagnostic algorithm

Connect a full-function scan tool and confirm P1757 plus any related codes. Record freeze-frame and live data while attempting shifts.
Inspect the solenoid B connector and harness for visible damage, corrosion, loose or pushed-out pins. Repair or clean as needed.
With ignition OFF, disconnect the solenoid connector and measure DC resistance of the solenoid coil between its terminals. Compare to spec. If highly low or shorted, replace the solenoid.
Check for short to ground or battery: measure resistance from each solenoid lead to chassis ground and to battery positive with connector disconnected. Low resistance to ground indicates a short.
With the connector back on, backprobe the control wire and command the TCM to activate solenoid B while observing voltage and waveform on a DVOM or scope. Look for proper supply voltage, switching and absence of shorted condition (voltage collapse).
Perform a wiggle test on wiring and connectors while monitoring the signal for intermittent shorts. Repair any damaged sections and secure harness away from heat/chafe points.
If wiring and solenoid check good, inspect the TCM connector and pins for damage and measure continuity from TCM driver pin to the solenoid connector. Replace or repair harness if open/shorts found.
If wiring, connector and solenoid are good but fault persists, consider TCM driver failure; confirm with isolation tests (disconnect solenoid and verify TCM behavior) before replacing TCM.
After repairs, clear codes, perform functional tests and a road test to verify normal shift operation and that the code does not return.

Likely causes

Wiring insulation damaged where harness passes near sharp edges or heat sources, creating a short
Solenoid connector corroded allowing unintended conductor contact
Shift solenoid has failed internally with very low resistance
Connector pins pushed out, bent, or shorting together
Aftermarket work or prior repairs produced a mis-routed or crushed harness
Intermittent TCM driver transistor failure

Fault status

⚠️ Status

TCM detected Shift Solenoid B circuit short (low resistance/short to power or ground).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 3.0 hours

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P1757 — Transmission Shift Solenoid B Circuit Shorted