P1818 GMC Code - Transmission Fluid Pressure Valve Position Switch-Drive Without 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
- P1818 GMC indicates Transmission Fluid Pressure Valve Position Switch-Drive Without 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 P1818 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 P1818 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 P1818 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 P1818 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.
Need more information about the P1818 GMC code?
Need more information on how to fix the P1818 GMC code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P1818 GMC code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about P1818 GMC Code
1. What are the common symptoms of OBDII code P1818 GMC?
The common symptoms of code P1818 GMC include harsh shifting, transmission slipping, and difficulty engaging gears.
2. What can cause the OBDII code P1818 GMC to trigger?
The code P1818 GMC is typically triggered by a faulty transmission fluid pressure valve position switch or issues with the drive without drive ratio.
3. How serious is OBDII code P1818 GMC?
Code P1818 GMC can affect the performance and reliability of your vehicle's transmission system. It is recommended to address this issue promptly to prevent further damage.
4. Can I continue driving my vehicle with OBDII code P1818 GMC?
It is not recommended to continue driving your vehicle with code P1818 GMC present, as it can lead to more severe transmission problems if left unaddressed.
5. How can I diagnose the cause of OBDII code P1818 GMC?
Diagnosing the cause of code P1818 GMC typically involves performing a thorough inspection of the transmission fluid pressure valve position switch and related components.
6. Is it possible to repair OBDII code P1818 GMC without professional help?
While some DIY enthusiasts may attempt to address code P1818 GMC on their own, it is advisable to seek professional help to ensure proper diagnosis and repair.
7. What are some repair tips for fixing OBDII code P1818 GMC?
Repair tips for code P1818 GMC may include checking and replacing the transmission fluid pressure valve position switch, inspecting wiring for damage, and ensuring proper adjustment of components.
8. How much does it cost to fix OBDII code P1818 GMC?
The cost of fixing code P1818 GMC can vary depending on the extent of the issue, parts needed for repair, and labor rates. It is recommended to obtain quotes from reputable mechanics.
9. Can OBDII code P1818 GMC be prevented?
Regular maintenance of the transmission system, including timely fluid changes and inspections, can help prevent issues that may trigger code P1818 GMC.
10. Will resetting the OBDII code P1818 GMC resolve the issue?
Resetting the OBDII code P1818 GMC may temporarily clear the code, but it will not address the underlying problem causing the code to trigger. It is important to diagnose and repair the issue to prevent future occurrences.
Discuss the causes and fixes for P1818 GMC OBDII Code
Code P1818 GMC comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
