What Does P0958 Mean?
DTC P0958 indicates the ASM mode selection circuit is producing a voltage signal above the expected maximum threshold. The TCM detects that the mode switch circuit voltage exceeds the highest valid mode position value, typically indicating an open circuit, disconnected switch, or signal wire shorted to the voltage reference. The TCM cannot determine the driver's intended mode selection.
Common Causes
30%
Disconnected mode selector switch connector
25%
Open circuit in the mode switch signal or ground wiring
20%
Mode switch with open internal contacts (broken resistor element)
15%
Signal wire shorted to 5V reference or battery voltage
10%
TCM connector pin backed out for the mode switch input
Diagnostic Steps
1
Step 1: Verify the mode selector switch connector is plugged in. An unplugged connector is the simplest cause of a high-circuit code on a resistor-ladder switch input.
2
Step 2: With the switch connected, measure the signal voltage at the TCM connector. If it reads at or near the 5V reference voltage, the circuit is open between the switch and TCM ground.
3
Step 3: Check the ground wire continuity from the mode switch connector to the TCM. An open ground will cause the signal to float high.
4
Step 4: Test the mode switch resistance in each position. If any position reads open (infinite resistance), the switch has failed internally.
5
Step 5: Inspect the signal wire routing for breaks, especially at stress points like connector entry points and harness flex areas. Repair any open circuits found.
6
Step 6: Replace the mode switch if it tests open in any position. Clear codes and cycle through all mode positions to verify proper recognition.
Estimated Repair Cost
$80 - $400
Parts + labor, varies by vehicle and location
DTC P0958 indicates the ASM mode selection circuit is producing a voltage signal above the expected maximum threshold. The TCM detects that the mode switch circuit voltage exceeds the highest valid mode position value, typically indicating an open circuit, disconnected switch, or signal wire shorted...
The most common cause of P0958 (Auto Shift Manual Mode Circuit High) is: Disconnected mode selector switch connector
Typical repair costs for P0958 range from $80 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A high mode circuit will cause the TCM to default to a standard operating mode. The vehicle remains fully functional and safe to drive. Mode selection is unavailable until the circuit is repaired, but this does not affect basic shifting or drivetrain operation.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0958 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Transmission / Mode Selection
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
