Engine-CodesPontiac – P1686 Pontiac

P1686 Pontiac Code - Transmission Control Module Power Up Temperature Sensor Circuit High Voltage

Quick Answer

The P1686 Pontiac code indicates a problem with the Transmission Control Module (TCM) Power Up Temperature Sensor Circuit, specifically detecting high voltage. Common causes include Faulty temperature sensor, Wiring issues in the temperature sensor circuit, Malfunctioning TCM. 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
P1686 Pontiac indicates Transmission Control Module Power Up Temperature Sensor Circuit High Voltage.
Common causes
Common causes include Faulty temperature sensor, Wiring issues in the temperature sensor circuit, Malfunctioning TCM.
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.
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code P1686 Pontiac Description

The P1686 Pontiac code indicates a problem with the Transmission Control Module (TCM) Power Up Temperature Sensor Circuit, specifically detecting high voltage. The TCM is responsible for controlling the transmission functions in the vehicle, such as shifting gears and ensuring optimal performance. The temperature sensor circuit plays a crucial role in monitoring the temperature of the transmission fluid to prevent overheating and ensure smooth operation.

OBDII Code P1686 Pontiac - Transmission Control Module Power Up Temperature Sensor Circuit High Voltage
P1686 Pontiac Code - Transmission Control Module Power Up Temperature Sensor Circuit High Voltage

Common Causes of P1686 Pontiac

  1. Faulty temperature sensor
  2. Wiring issues in the temperature sensor circuit
  3. Malfunctioning TCM
  4. Corrosion or damage to electrical connections
  5. Overheating of the transmission fluid

Symptoms of P1686 Pontiac

  1. Erratic shifting patterns
  2. Hesitation during acceleration
  3. Decreased fuel efficiency
  4. Transmission slippage
  5. Check Engine Light illuminated

How to Fix P1686 Pontiac

  1. Diagnose the root cause of the high voltage in the temperature sensor circuit using a diagnostic scanner and multimeter.
  2. Inspect the wiring and electrical connections for any signs of damage or corrosion.
  3. Test the temperature sensor for proper function and replace if necessary.
  4. If the issue persists, check the TCM for faults and consider reprogramming or replacing it.
  5. Clear the trouble codes, reset the TCM, and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P1686 Pontiac

The cost of repairing the P1686 Pontiac code can vary depending on the specific cause of the issue and the labor rates at the auto repair shop. On average, the repair costs for this issue can range from $200 to $500, including parts and labor. However, it's important to note that the actual cost may be higher or lower based on the extent of the repairs needed and the prices of the replacement parts. It is recommended to consult with a professional mechanic or dealership for a more accurate estimate based on your vehicle model and location.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1686 Pontiac Code

1. What does the OBDII code P1686 mean on a Pontiac?

P1686 indicates an issue with the Transmission Control Module (TCM) Power Up Temperature Sensor Circuit, specifically detecting a high voltage condition.

2. What are the common symptoms of a P1686 code in a Pontiac?

Symptoms may include transmission shifting issues, erratic gear changes, the transmission going into limp mode, or the check engine light being illuminated.

3. What causes the P1686 code to appear?

Common causes include a faulty temperature sensor, damaged or corroded wiring, a malfunctioning Transmission Control Module (TCM), or electrical issues such as a short circuit.

4. Can a bad TCM cause the P1686 code?

Yes, a malfunctioning TCM can cause the P1686 code if it fails to properly process signals from the temperature sensor.

5. How do I diagnose the P1686 code?

Diagnose the code by checking the wiring and connectors for damage, testing the temperature sensor for proper operation, and using a scan tool to monitor voltage readings.

6. Is it safe to drive with a P1686 code?

Driving with a P1686 code may cause further damage to the transmission or other components, so it’s recommended to address the issue promptly.

7. How is the P1686 code fixed?

Repairs include replacing the faulty temperature sensor, repairing or replacing damaged wiring, or reprogramming or replacing the TCM if necessary.

8. Can a software update fix the P1686 code?

In some cases, a software update for the TCM may resolve the issue if it’s caused by a programming error rather than a hardware fault.

9. How much does it cost to repair a P1686 code?

Repair costs vary, but replacing a temperature sensor may cost $100-$300, while TCM replacement or reprogramming can range from $500-$1,200.

10. Can a loose connector trigger the P1686 code?

Yes, a loose or corroded connector can disrupt the sensor’s voltage signal, leading to the P1686 code being triggered.

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