P185F 2018 GMC Sierra Code - Transfer Case Shift Pending Signal Not Plausible
Quick Answer
The Engine Control Module (ECM) uses the following two ways to determine if the transfer case is in 4WD Low, 4WD High, or Neutral. Common causes include Reprogram Engine Control Module (ECM), Faulty Engine Control Module, Engine Control Module harness is open or shorted. 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
- P185F 2018 GMC Sierra indicates Transfer Case Shift Pending Signal Not Plausible.
- Common causes
- Common causes include Reprogram Engine Control Module (ECM), Faulty Engine Control Module, Engine Control Module harness is open or shorted.
- 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 P185F 2018 GMC Sierra Description
1. The first way is to compare the transmission output speed sensor to the transfer case output speed sensor in order to calculate the transfer case range.
2. The second way is to use a LAN message sent by the transfer case shift control module to the ECM.
The ECM uses this message to determine motor torque required and transmission shifting.
The internal fault detection is handled inside the control module. No external circuit diagnosis is involved.
If the first way and second way of determining transfer case range do not match while in 4WD Low, 4WD High or Neutral, then the Diagnostic Trouble Code (DTC) is set.
What are the Possible Causes of the DTC P185F 2018 GMC Sierra?
- Reprogram Engine Control Module (ECM)
- Faulty Engine Control Module
- Engine Control Module harness is open or shorted
- Engine Control Module circuit poor electrical connection
- Transmission internal mechanical problems
How to Fix the DTC P185F 2018 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 P185F 2018 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 P185F 2018 GMC Sierra Code
1. What does the OBDII code P185F mean for a 2018 GMC Sierra?
The code P185F indicates a "Transfer Case Shift Pending Signal Not Plausible," meaning the transfer case control module is detecting an issue with the shift signal or its plausibility.
2. What are common symptoms of the P185F code in a 2018 GMC Sierra?
Symptoms may include the "Service 4WD" light illuminating, difficulty shifting between 4WD modes, the transfer case not engaging properly, or the vehicle being stuck in a specific drive mode.
3. What causes the P185F code to trigger?
Possible causes include a faulty transfer case control module, wiring or connection issues, a malfunctioning transfer case shift motor, or software-related glitches.
4. Can driving with the P185F code cause damage to the vehicle?
Driving with this code may lead to improper 4WD operation, reduced performance, or damage to the transfer case if not addressed promptly.
5. How do you diagnose the P185F code on a 2018 GMC Sierra?
Diagnosis includes scanning for codes, inspecting the transfer case control module, checking the wiring and connections, and testing the transfer case shift motor for proper operation.
6. What tools are needed to troubleshoot the P185F code?
You’ll need an OBDII scanner capable of reading manufacturer-specific codes, a multimeter for checking electrical connections, and possibly a service manual for the vehicle.
7. How do you fix the P185F code on a GMC Sierra?
Repairs may involve replacing the transfer case control module, repairing damaged wiring or connectors, recalibrating the system, or replacing the transfer case shift motor if faulty.
8. Is the P185F code a common issue in the 2018 GMC Sierra?
While not extremely common, it can occur in vehicles with higher mileage or those frequently used in 4WD conditions.
9. What is the cost of repairing the P185F code?
Repair costs vary depending on the issue. A transfer case control module replacement can cost $300–$800, while wiring repairs or reprogramming may be less expensive.
10. Can the P185F code be cleared without repairs?
You can clear the code temporarily with an OBDII scanner, but it will likely return if the underlying issue isn’t resolved.
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