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DTC codes / P09xx · Transmission / P0952

P0952Auto Shift Manual Control Circuit Low

P0952 indicates that the transmission control module (TCM) has detected a low-voltage condition on the electrical circuit for the auto shift manual control, which is the driver-operated gear selection input for an automated manual or dual-clutch transmission. The computer expects a specific voltage range on the signal circuit and sees a value below the acceptable threshold, which can prevent the TCM from knowing the driver's intended gear or mode.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaTransmission

Symptoms you may notice

  • The malfunction indicator lamp (MIL) illuminates on the dashboard, often with no other noticeable symptoms.
  • The transmission may refuse to engage drive or reverse, or may stay in a single gear.
  • Gear selection buttons or paddles may feel unresponsive or require multiple presses.
  • The instrument cluster may display a transmission fault message or flash the gear indicator.
  • The vehicle may enter limp mode, limiting engine power and speed.
  • In some cases, the engine may crank but not start because the TCM inhibits starting when it cannot confirm the control position.

Common causes, most likely first

  1. A faulty auto shift manual control switch or selector assembly that internally shorts the signal circuit to ground.
  2. Damaged or corroded wiring in the control circuit, such as a chafed wire touching ground or a broken connector pin.
  3. Water intrusion into the selector assembly or its connector, causing low resistance to ground.
  4. A poor ground connection for the TCM or the control circuit, which skews the signal voltage low.
  5. A failed TCM driver or internal circuit that incorrectly reads the signal as low.
  6. Aftermarket accessories or poor previous repairs that tapped into the control circuit and introduced a ground fault.

How to diagnose and fix it

  1. Connect a scan tool and record all stored and pending codes, then clear codes and test-drive to see if P0952 returns immediately.
  2. Inspect the auto shift manual control switch and its connector for corrosion, water intrusion, or loose pins, and clean or repair as needed.
  3. Disconnect the control switch and measure resistance from the signal wire to ground; a reading below specification indicates a short in the harness or switch.
  4. Check the TCM ground connections and the control circuit ground for excessive resistance using a voltage drop test.
  5. Back-probe the control signal wire at the TCM while operating the selector and compare the voltage to the manufacturer's specification to isolate the switch from the harness.
  6. If the switch and wiring test good, substitute a known-good TCM or perform a relearn/calibration procedure as required by the manufacturer.
  7. After repairs, clear codes and perform a road test to confirm the transmission selects gears correctly and the code does not reset.

What the low circuit reading really means

  • A low signal voltage often comes from a switch that is internally shorted to ground, not from a failed TCM, so test the switch before condemning the module.
  • Water intrusion into the shifter assembly is a common cause that many technicians miss because the connector looks dry until the housing is opened.
  • The code can set intermittently from a chafed wire that only touches ground when the engine moves under load, so a wiggle test of the harness is essential.
  • A weak battery or charging system can cause the TCM to misread the control voltage, so always verify battery voltage and ground quality first.
  • Aftermarket remote starters or alarm systems that tap into the shifter wiring frequently introduce this fault and are often overlooked during diagnosis.

Can I keep driving with P0952?

You can usually drive the vehicle to a repair shop if it still selects gears and does not enter limp mode, but avoid highway speeds and heavy traffic because the transmission may suddenly refuse to change gears. If the vehicle will not engage drive or reverse, do not attempt to drive it and have it towed.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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