P18C0 2017 GMC Sierra Code - Internal Mode Switch 'B' Circuit Stuck On Invalid Voltage Range
Quick Answer
The internal mode switch indicates the Transmission Control Module (TCM) which gear position the vehicle operator has selected. Common causes include Faulty Transmission Internal Mode Switch, Transmission Internal Mode Switch harness is open or shorted, Transmission Internal Mode Switch circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P18C0 2017 GMC Sierra indicates Internal Mode Switch 'B' Circuit Stuck On Invalid Voltage Range.
- Common causes
- Common causes include Faulty Transmission Internal Mode Switch, Transmission Internal Mode Switch harness is open or shorted, Transmission Internal Mode Switch circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P18C0 2017 GMC Sierra Description
What are the Possible Causes of the DTC P18C0 2017 GMC Sierra?
- 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)
How to Fix the DTC P18C0 2017 GMC Sierra?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P18C0 2017 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about P18C0 2017 GMC Sierra Code
1. What does the OBDII code P18C0 mean on a 2017 GMC Sierra?
The code P18C0 indicates an issue with the Internal Mode Switch 'B' circuit, which is stuck on an invalid voltage range. This typically relates to the transmission range sensor or associated wiring.
2. What are the common symptoms of P18C0 in a 2017 GMC Sierra?
Symptoms may include the check engine light turning on, erratic shifting, transmission stuck in one gear, or the vehicle not starting.
3. What causes the P18C0 code to appear in a GMC Sierra?
The primary causes include a faulty internal mode switch, damaged wiring or connectors in the circuit, a failing transmission control module (TCM), or corrosion affecting electrical connections.
4. Can a bad internal mode switch cause transmission problems in a 2017 GMC Sierra?
Yes, a faulty internal mode switch can cause the transmission to send incorrect gear signals, leading to shifting issues or the transmission becoming stuck in a single gear.
5. How do I diagnose the P18C0 code on my GMC Sierra?
Diagnosing this code involves checking the internal mode switch, inspecting wiring and connectors for damage or corrosion, and testing the TCM for proper operation using a scan tool.
6. Is the P18C0 code serious on a GMC Sierra?
Yes, this code can lead to drivability issues, including unsafe or erratic shifting. It should be addressed promptly to avoid further transmission damage.
7. Can I drive my 2017 GMC Sierra with a P18C0 code?
While the vehicle might be drivable, it’s not recommended since erratic shifting could cause additional transmission damage or create unsafe driving conditions.
8. How much does it cost to fix the P18C0 code on a GMC Sierra?
Repair costs can vary but may range from $150 to $600 depending on whether the issue is with wiring, the internal mode switch, or the transmission control module.
9. Can I fix the P18C0 code on my GMC Sierra myself?
If you’re experienced with automotive electrical systems, you can inspect and repair damaged wiring or replace the internal mode switch. Otherwise, it’s best to consult a professional mechanic.
10. Will clearing the P18C0 code with a scan tool fix the problem?
Clearing the code will temporarily remove it, but the underlying issue must be resolved to prevent the code from returning.
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