Transmission Fluid Pressure Valve Position Switch-Drive Without Drive Ratio
Table of contents
P1818 PONTIAC Possible Causes
- 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 do I fix code P1818 PONTIAC?
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.
Tech Notes
- If the Service Engine Soon (SES) light (Code P1818), the power door locks, cruise control, shift interlock, retractable hardtop being inoperative and engine speed revs limited to 4,000 RPM in first gear after a cold start or cold soak with temperatures between 0° to 10°C (32°F to 50°F). These conditions may be caused by the TCM setting a false DTC P1818 (Transmission Fluid Pressure (TFP) Valve Position Switch Indicates Drive without Drive Ratio). Verify the conditions and reprogram the transmission control module (TCM) with the new updated calibration.
Cost of diagnosing the P1818 PONTIAC code
The cost of diagnosing the P1818 PONTIAC code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
P1818 PONTIAC Description
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. The combined unit mounts on the valve body.
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.