P1838 2017 GMC Sierra Code - Internal Mode Switch 'A' Circuit High Voltage
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
- P1838 2017 GMC Sierra indicates Internal Mode Switch 'A' Circuit High Voltage.
- 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 P1838 2017 GMC Sierra Description
What are the Possible Causes of the DTC P1838 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 P1838 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 P1838 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.
Need more information about the P1838 2017 GMC Sierra code?
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Frequently Asked Questions about P1838 2017 GMC Sierra Code
1. What does the OBDII code P1838 mean on a 2017 GMC Sierra?
P1838 indicates a high voltage issue in the Internal Mode Switch (IMS) 'A' circuit, which is part of the transmission range sensor system.
2. What are the common symptoms of code P1838 in a 2017 GMC Sierra?
Symptoms may include erratic shifting, the transmission stuck in one gear, a check engine light, or reduced performance.
3. What causes code P1838 to appear in a 2017 GMC Sierra?
Common causes include a faulty Internal Mode Switch, damaged wiring or connectors in the IMS circuit, or issues with the transmission control module (TCM).
4. Can driving with the P1838 code damage my 2017 GMC Sierra?
Yes, driving with this issue can cause further transmission damage or unsafe driving conditions due to improper shifting.
5. How is code P1838 diagnosed in a 2017 GMC Sierra?
A technician will use a scan tool to read live data, inspect the IMS circuit for wiring damage or loose connections, and test the switch for proper operation.
6. How can I fix the P1838 code on my 2017 GMC Sierra?
Repairs may include replacing the Internal Mode Switch, repairing or replacing damaged wiring, or reprogramming/updating the transmission control module.
7. What tools are needed to fix the P1838 code on my 2017 GMC Sierra?
Basic tools like a multimeter for testing voltage, a scan tool for diagnostics, and possibly specialized tools for accessing and replacing the IMS.
8. How much does it cost to repair code P1838 on a 2017 GMC Sierra?
The cost can vary, but replacing the Internal Mode Switch typically ranges from $150 to $400, depending on parts and labor.
9. Can a failing battery cause the P1838 code on a 2017 GMC Sierra?
While unlikely, a weak or failing battery can cause voltage irregularities that might trigger transmission-related codes, including P1838.
10. Is the P1838 code specific to GMC vehicles?
No, while the code can appear on other vehicles, it is manufacturer-specific and tailored to GM's Internal Mode Switch circuit issues.
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