P0952

Code

Generic P — Powertrain

Auto Shift Manual Control Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 33 EN: 42 RU: 28

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Page language: EN

Causes

Open, short to ground, or high-resistance in ASM control wiring or connector
Corroded or loose connector pins at the switch, switch harness, or TCM/ECM
Faulty Auto Shift/Manual switch or position sensor
Blown fuse or poor power/ground to related circuits
Faulty Transmission Control Module (TCM) or PCM input circuit

Symptoms

Malfunction Indicator Lamp (MIL) or transmission warning lamp illuminated
Loss of manual shift function or inability to engage manual mode
Transmission may default to limp/backup mode or default shift program
Shift indicator not matching selected gear or no response from shift command
Intermittent operation or symptoms that change when wiring is moved

What to check

Read freeze frame and live data with a scan tool — note ASM input status and related transmission data
Visually inspect wiring and connectors for damage, corrosion, or pushed-out pins at switch, transmission, and TCM
Check fuses and main power/ground feeds for the transmission/shift circuit
Backprobe the ASM connector and TCM input with key ON to measure voltage and signal state
Wiggle test wiring while monitoring the signal to reproduce intermittent faults

Signal parameters

Reference voltage: often a 5 V reference or switched battery voltage depending on vehicle — confirm with OEM wiring diagram
Low condition (fault reported): signal near 0–0.5 V (indicates short to ground or pulled low)
Normal/High: signal near the reference voltage (e.g., ≈5 V or battery voltage when switched)
Continuity: expected low resistance between switch output and TCM input when closed; open = high/OL
Watch for sudden drops to low voltage when operating the shift selector (live-data behavior)

Diagnostic algorithm

Retrieve freeze frame and live data; confirm P0952 is current and check for related transmission/TCM codes.
Inspect ASM switch, shift lever assembly, wiring harness, and connectors for obvious damage, corrosion or loose pins.
Check relevant fuses and battery/ignition power feeds and chassis/engine/transmission grounds.
Backprobe the ASM switch output and the corresponding TCM input with key ON; record voltage and compare to expected reference.
Perform a wiggle/pressure test on the harness while monitoring the signal to identify intermittent opens/grounds.
If signal is low, disconnect the ASM switch; measure resistance to ground and to the TCM input. Repair short to ground or replace damaged wiring.
If wiring and switch test good, swap or bench-test the ASM switch (if serviceable) or replace. Re-test.
If wiring and switch check OK and fault persists, inspect/replace the TCM or repair the input circuit per OEM procedures.
Clear codes, perform road test and monitor for return of the code.

Likely causes

Wiring harness chafed and shorted to chassis ground near shift lever or transmission
Connector terminal pushed out or corroded at the ASM switch
Failure of the manual shift selector/switch assembly
Blown fuse supplying the circuit or poor ground at transmission or body ground
Internal TCM/PCM input fault (less common)

Fault status

⚠️ Status

Transmission control module detected low voltage/low signal on the Auto Shift/Manual control circuit — check wiring, connectors, fuses, switch, and module input.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours