P1838 2015 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 2015 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 2015 GMC Sierra Description
What are the Possible Causes of the DTC P1838 2015 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 2015 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 2015 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 P1838 2015 GMC Sierra Code
1. What does the OBDII code P1838 mean on a 2015 GMC Sierra?
P1838 indicates that the Internal Mode Switch (IMS) 'A' circuit is experiencing a high voltage condition, which can affect transmission operation.
2. What are the common symptoms of code P1838 on a 2015 GMC Sierra?
Symptoms may include the transmission stuck in one gear, erratic shifting, the Check Engine Light illuminating, or reduced vehicle performance.
3. What causes the P1838 code in a 2015 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 a loose or corroded connection cause the P1838 code?
Yes, loose or corroded electrical connections in the IMS circuit can lead to high voltage readings and trigger the P1838 code.
5. How do I diagnose the P1838 code on my 2015 GMC Sierra?
Start by inspecting the IMS wiring and connectors for damage or corrosion. Use a multimeter to check for proper voltage levels and test the IMS for functionality.
6. Can driving with the P1838 code damage my 2015 GMC Sierra?
Driving with this code can lead to further transmission issues or unsafe vehicle operation, so it's best to address the issue promptly.
7. How do I fix the P1838 code on a 2015 GMC Sierra?
Repairs may include replacing the Internal Mode Switch, repairing or replacing damaged wiring, cleaning corroded connections, or reprogramming the TCM if necessary.
8. Is the P1838 code specific to the 2015 GMC Sierra?
No, the P1838 code can occur in other vehicles equipped with similar transmission systems, but the exact diagnosis and repair steps may vary.
9. How much does it cost to fix the P1838 code on a 2015 GMC Sierra?
Repair costs depend on the root cause but can range from $150 to $500, including diagnostics, parts, and labor.
10. Can a bad Transmission Control Module (TCM) trigger the P1838 code?
Yes, a malfunctioning TCM could misinterpret voltage signals from the IMS, potentially causing the P1838 code.
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