Code
P0750
MITSUBISHI
P — Powertrain
LR solenoid
Views:
UK: 17
EN: 31
RU: 24
AI status
Completed
Completed
100%
Causes
- Open or short in the LR solenoid wiring harness
- Poor or corroded connector(s) at the solenoid or TCM/PCM
- Defective LR solenoid (coil shorted or open)
- Faulty TCM/PCM driver transistor or internal electronics
- Low battery/voltage supply or charging system issues
- Contaminated or degraded transmission fluid causing solenoid sticking
Symptoms
- MIL (check engine light) illuminated
- Transmission may fail to shift, shift late, or slip
- Erratic or harsh shift feel
- Transmission stuck in one gear or limp/limitation mode
- Stored transmission-related trouble codes
- Possible abnormal noises from the transmission
What to check
- Read and record all stored transmission codes and freeze frame data
- Check battery voltage and charging system condition
- Inspect transmission fluid level and condition (burnt smell, contamination)
- Visually inspect wiring harness and connectors for damage and corrosion
- Measure resistance of LR solenoid coil at the connector
- Backprobe solenoid connector to observe PCM drive signal during cranking/shift
Signal parameters
- Nominal supply voltage: 11–14.5 V (battery/ignition ON)
- Typical solenoid coil resistance (typical range): ~10–50 Ω (check specific service data)
- PCM drives solenoid with switched ground or PWM; duty cycle varies with command
- Activation frequency for PWM control: commonly tens to low hundreds of Hz (vehicle-specific)
- Expected continuity: low ohms (not open); no high resistance or short to ground/power
Diagnostic algorithm
- Connect a scan tool, read/record P0750 and any additional codes; note freeze frame and conditions when the code set.
- Verify battery voltage is within specification; charge or repair charging system if low.
- Visually inspect LR solenoid connector and wiring to the transmission and TCM/PCM for damage, corrosion, pin pushed out, or chafing.
- Unplug the LR solenoid connector and measure coil resistance at the solenoid pins; compare to the vehicle's service specification. Replace solenoid if open or out of range.
- With connector disconnected, check for short to battery or ground from the harness using an ohmmeter (check continuity to ground and to +B).
- Backprobe the harness at the solenoid connector with ignition ON and during commanded shifts; verify PCM supplies battery voltage or switched ground/PWM and that the circuit response changes when commanded by the scan tool.
- Wiggle test the harness/connector while monitoring signal and resistance to detect intermittent faults.
- If wiring checks good and solenoid good, test for proper TCM/PCM drive: inspect PCM connector pins for damage; if PCM output is absent or stuck, consider PCM fault or intermediate harness/relay/fuse.
- Check transmission fluid condition and level; replace if contaminated or burnt as contaminated fluid can cause internal solenoid sticking.
- After repairs or replacement, clear codes and perform a road test and functional tests with scan tool to confirm proper operation and that P0750 does not return.
- If fault persists after solenoid and wiring verified, consult manufacturer technical service information for PCM testing or reprogramming, and consider professional diagnosis of internal transmission faults.
Likely causes
- Broken wire or chafed insulation to LR solenoid
- Corroded pins or water ingress at solenoid connector
- High resistance in circuit due to poor ground
- Solenoid coil failed (open or shorted)
- PCM output transistor fault
- Low battery voltage during operation
Fault status
Status
Transmission LR solenoid circuit malfunction detected by control module. MIL illuminated; code stored and freeze frame captured. Transmission performance may be limited (limp mode) until fault is resolved.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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