Code
P1758
LAND ROVER
P — Powertrain
Incorrect current of the pressure solenoid control system
Views:
UK: 9
EN: 13
RU: 17
AI status
Completed
Completed
100%
Causes
- Open or short in solenoid feed or ground wiring
- Corroded, loose, or damaged connector or pin at solenoid or TCM
- Faulty pressure control solenoid (stuck, shorted or internally open)
- Low battery voltage or poor battery/charging system condition
- Faulty TCM or internal driver circuit
- Contaminated transmission fluid or internal hydraulic fault causing abnormal load on solenoid
Symptoms
- Check Engine / transmission warning lamp illuminated
- Harsh, delayed, or erratic shifting
- Transmission may enter limp mode or default gear
- Reduced driveability or inability to change gears
- Stored DTCs related to other transmission solenoids or pressure faults
What to check
- Retrieve freeze-frame and all related codes with scan tool; note engine/transmission operating conditions when the code set
- Inspect wiring harness and connectors at the pressure solenoid and TCM for corrosion, damage, pin push-out or moisture
- Check battery voltage and charging system under load
- Measure solenoid coil resistance (with ignition off) and compare to specification
- Monitor live data: solenoid current, commanded duty cycle, and transmission pressure (if available)
- Perform back-probe voltage/current checks while operating (use proper clamps/meter rated for automotive use)
Signal parameters
- Solenoid coil resistance: consult factory service manual (typical range often ~5–100 Ohms depending on design)
- Control current when activated: varies by model; commonly up to a few amps — consult spec
- Control voltage at solenoid connector (commanded): 0 V (off) to battery voltage or PWM duty as commanded by TCM
- PWM duty cycle (%) when pressure control is commanded
- Transmission hydraulic pressure (kPa or psi) vs. commanded value
Diagnostic algorithm
- Verify the code and note freeze frame. Confirm the code is current and repeatable.
- Visually inspect connectors and wiring for damage, corrosion, or loosened pins at the solenoid and TCM. Repair any damage.
- Check battery voltage and charging system; ensure proper supply voltage to TCM/solenoid circuits.
- With ignition off, measure solenoid coil resistance and compare to spec. Replace solenoid if out of range.
- With safe access, back-probe the solenoid connector. With engine running/gear engaged as required by procedure, monitor voltage, duty cycle, and measure current with a clamp meter while commanding the solenoid through a scan tool.
- If current is too high or too low with correct command and good supply voltage, suspect a faulty solenoid or internal short. If current is intermittent or changes with harness movement, repair wiring/connector.
- If wiring and solenoid check good, test TCM output stage by measuring driver signals. If driver is faulty, replace or reprogram TCM per manufacturer guidance.
- After repair, clear codes and perform road test under the same conditions that caused the code to confirm repair.
- If transmission hydraulic pressure is abnormal despite correct solenoid operation, investigate internal transmission faults or valve body issues.
Likely causes
- Damaged wiring or poor connector (most common)
- Failed pressure control solenoid
- Corroded ground or poor battery/charging condition
- TCM driver fault (less common)
Fault status
Status
Pressure solenoid control circuit current out of range / incorrect current detected
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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