What Does P0957 Mean?
DTC P0957 indicates the ASM mode selection circuit is producing a voltage signal below the expected minimum threshold. The TCM receives a low signal from the mode switch circuit, which may not correspond to any valid mode position. This typically indicates a short to ground in the mode switch circuit, a failed switch, or a wiring issue pulling the signal voltage down.
Common Causes
30%
Mode switch signal wire shorted to ground
25%
Mode selector switch with internal short to ground
20%
Corroded connector causing low-resistance path to ground
15%
Wiring harness damage under center console (pinched or chafed wire)
10%
Liquid spill on the mode switch creating a conductive path to ground
Diagnostic Steps
1
Step 1: Disconnect the mode switch connector and check the signal voltage at the harness side with the key on. If the voltage rises to the reference voltage with the switch disconnected, the switch is shorted.
2
Step 2: Test the mode switch itself for a short to ground by measuring resistance between the signal terminal and the ground terminal. Compare to specifications for each mode position.
3
Step 3: Inspect the mode switch area for evidence of liquid spills (coffee, water, soda) that could create a conductive film shorting the circuit to ground.
4
Step 4: Check the wiring harness from the switch to the TCM for shorts to ground, particularly where wires route under the center console and through floor panel grommets.
5
Step 5: Replace the mode selector switch if it tests shorted. Clean and dry the switch area thoroughly before installing the new switch. Clear codes and verify all modes register correctly.
Estimated Repair Cost
$80 - $400
Parts + labor, varies by vehicle and location
DTC P0957 indicates the ASM mode selection circuit is producing a voltage signal below the expected minimum threshold. The TCM receives a low signal from the mode switch circuit, which may not correspond to any valid mode position. This typically indicates a short to ground in the mode switch circui...
The most common cause of P0957 (Auto Shift Manual Mode Circuit Low) is: Mode switch signal wire shorted to ground
Typical repair costs for P0957 range from $80 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A low mode circuit will cause the TCM to default to a standard operating mode. The vehicle remains fully drivable but the driver cannot select alternative transmission modes. This is not a safety-critical fault.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0957 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission / Mode Selection
Difficulty
Type
Generic (SAE)
Recommended Tools
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