P1816 GMC Code - Transmission Fluid Pressure Valve Position Switch-Park/Neutral With Drive Ratio
Quick Answer
The automatic Transmission Fluid Pressure (TFP) manual valve position switch consists of five pressure switches (two normally-closed and three normally-open) and a Transmission Fluid Temperature (TFT) sensor combined into one unit. Common causes include Faulty Automatic Transmission Fluid Pressure (TFP) Manual Valve Position Switch, TFP Valve Position Switch harness is open or shorted, TFP Valve Position 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
- P1816 GMC indicates Transmission Fluid Pressure Valve Position Switch-Park/Neutral With Drive Ratio.
- Common causes
- Common causes include Faulty Automatic Transmission Fluid Pressure (TFP) Manual Valve Position Switch, TFP Valve Position Switch harness is open or shorted, TFP Valve Position 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 P1816 GMC Description
The Powertrain Control Module (PCM) supplies ignition voltage for each range signal. By grounding one or more of the circuits through various combinations of the pressure switches, the PCM detects which manual valve position you select. The PCM compares the actual voltage combination of the switches to a TFP manual valve position switch combination table stored in memory.
The TFP manual valve position switch cannot distinguish between PARK and NEUTRAL because the monitored valve body pressures are identical. With the engine OFF and the ignition switch in the RUN position, the TFP manual valve position switch indicates PARK or NEUTRAL. Disconnecting the AT inline 20-way connector removes the ground potential for the three range signals to the PCM. In this case, with the engine OFF, and the ignition switch in the RUN position, D2 will be indicated.
What are the Possible Causes of the DTC P1816 GMC?
- Faulty Automatic Transmission Fluid Pressure (TFP) Manual Valve Position Switch
- TFP Valve Position Switch harness is open or shorted
- TFP Valve Position Switch circuit poor electrical connection
How to Fix the DTC P1816 GMC?
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 P1816 GMC 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 P1816 GMC Code
1. What does the GMC OBDII code P1816 indicate?
The P1816 code refers to a Transmission Fluid Pressure (TFP) Valve Position Switch issue, specifically when the Park/Neutral position is detected while a drive ratio is engaged.
2. What are common symptoms of the P1816 code in a GMC vehicle?
Symptoms may include the transmission stuck in one gear (limp mode), delayed or harsh shifting, the Check Engine Light illuminated, or erratic speedometer readings.
3. What causes the P1816 code to appear on a GMC vehicle?
The code is commonly caused by a faulty TFP Valve Position Switch, wiring issues (corrosion, damage, or loose connections), or internal transmission problems, such as a hydraulic failure.
4. Can driving with the P1816 code damage my GMC transmission?
Yes, continuing to drive with this code can cause further transmission damage due to improper shifting or overheating, so it should be diagnosed and repaired promptly.
5. How do I diagnose the P1816 code on my GMC vehicle?
Diagnosis involves checking the TFP Valve Position Switch, inspecting wiring and connectors for damage or corrosion, and using a scan tool to monitor transmission data for abnormalities.
6. How is the P1816 code typically repaired?
Repairs may involve replacing the TFP Valve Position Switch, repairing or replacing damaged wiring, or addressing any internal transmission issues.
7. What tools are needed to fix the P1816 code on a GMC?
You’ll typically need a scan tool for diagnostics, a multimeter for testing the electrical circuit, and basic hand tools to access and replace components.
8. Is the P1816 code specific to GMC vehicles?
While the P1816 code is commonly associated with GMC vehicles, it may also appear on other vehicles equipped with similar systems.
9. How much does it cost to fix the P1816 code on a GMC?
The repair cost can vary based on the specific issue but typically ranges from $150 to $500, depending on whether a sensor, wiring repair, or transmission service is needed.
10. Can low transmission fluid cause the P1816 code?
Low transmission fluid may not directly trigger the P1816 code, but it can cause transmission issues that lead to similar symptoms or contribute to sensor malfunctions.
Discuss the causes and fixes for P1816 GMC OBDII Code
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