What Does P1780 Mean?
The transmission control switch circuit is reading values outside the expected range during self-test procedures. This typically involves the manual shift selector or transmission mode switch providing incorrect voltage or resistance values.
Common Causes
40%
Faulty transmission control switch or shifter position sensor
30%
Open or short circuit in transmission switch wiring
18%
Corroded or damaged connector terminals at switch
7%
Misadjusted shift linkage affecting switch position
5%
Failed TCM unable to read switch properly
Diagnostic Steps
1
Step 1: Verify proper operation of all transmission switch functions and modes
2
Step 2: Check voltage or resistance values at switch connector in each gear position
3
Step 3: Inspect connector terminals for corrosion, bent pins, or poor contact
4
Step 4: Test wiring continuity from switch to TCM connector
5
Step 5: Monitor switch signal using scan tool live data while moving through positions
Estimated Repair Cost
$175 - $650
Parts + labor, varies by vehicle and location
The transmission control switch circuit is reading values outside the expected range during self-test procedures. This typically involves the manual shift selector or transmission mode switch providing incorrect voltage or resistance values.
The most common cause of P1780 (Transmission Control Switch circuit is out of Self-Test Range) is: Faulty transmission control switch or shifter position sensor
Typical repair costs for P1780 range from $175 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
May cause incorrect gear selection or prevent shifting. Vehicle may be stuck in one gear or fail to respond to driver input.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1780 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission Control System
Difficulty
Type
Manufacturer
Recommended Tools
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