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P18C3 Code - Internal Mode Switch 'S' Circuit Stuck On Invalid Voltage Range

- Code Popularity: 1,392 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
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What are the Possible Causes of the DTC P18C3?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Faulty Transmission Internal Mode Switch
  • Transmission Internal Mode Switch harness is open or shorted
  • Transmission Internal Mode Switch circuit poor electrical connection
  • Faulty Transmission Control Module (TCM)
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How to Fix the DTC P18C3?

Review the 'Possible Causes' mentioned above and visually examine the corresponding wiring harness and connectors. Ensure to check for any damaged components and inspect the connector pins for signs of being broken, bent, pushed out, or corroded.

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P18C3 code, it typically requires 1.0 hour of labor. The specific diagnosis time and labor rates at auto repair shops can differ based on factors such as the location, make and model of the vehicle, and even the engine type. It is common for most auto repair shops to charge between $75 and $150 per hour.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

Code P18C3 Description

The internal mode switch indicates the Transmission Control Module (TCM) which gear position the vehicle operator has selected. The internal mode switch consists of 5 separate hall effect switches. Each hall effect switch is supplied with a 9 V reference circuit and a signal circuit from the TCM. Each signal circuit for each gear selector position will have either a voltage reading of 0.70–0.96 V indicating On or 1.68–2.38 V indicating Off. The voltage values on each internal mode switch circuit will change and are dependent on the position of the gear selector. The state of each internal mode switch A/B/C/P/S signal circuit is displayed on the scan tool. The Diagnostic Trouble Code (DTC) will be set when the TCM has detected has an internal mode switch S signal circuit has an invalid voltage range of 0.70 – 0.96 V, for 2.7 s.

OBDII Code P18C3 - Internal Mode Switch 'S' Circuit Stuck On Invalid Voltage Range - AutoCodes.com
P18C3 Code - Internal Mode Switch 'S' Circuit Stuck On Invalid Voltage Range

Need More Information on the Code?

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Information for Specific Makes

  • P18C3 Buick Internal Mode Switch 'S' Circuit Stuck On Invalid Voltage Range  📷
  • P18C3 Cadillac Internal Mode Switch 'S' Circuit Stuck On Invalid Voltage Range  📷
  • P18C3 Chevrolet Internal Mode Switch 'S' Circuit Stuck On Invalid Voltage Range  📷
  • P18C3 GMC Internal Mode Switch 'S' Circuit Stuck On Invalid Voltage Range  📷

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Code P18C3 comments

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