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Engine-Codes – GMC – P0708 GMC

P0708 GMC Code - Transmission Range Switch Circuit High Voltage

Quick Answer

The P0708 code for GMC vehicles indicates a problem with the Transmission Range Switch Circuit High Voltage. Common causes include Faulty transmission range switch, Damaged wiring or connectors in the circuit, Corrosion or water damage to the switch. 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
P0708 GMC indicates Transmission Range Switch Circuit High Voltage.
Common causes
Common causes include Faulty transmission range switch, Damaged wiring or connectors in the circuit, Corrosion or water damage to the switch.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 06, 2024
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Code P0708 GMC Description

The P0708 code for GMC vehicles indicates a problem with the Transmission Range Switch Circuit High Voltage. This switch, also known as the neutral safety switch, is responsible for ensuring that the transmission is in the correct gear before the vehicle can be started. When this circuit detects a high voltage, it means that there is an issue with the switch's operation, potentially leading to incorrect gear selection or failure to start the vehicle. This can result in erratic shifting, stalling, or even the inability to move the vehicle at all.

OBDII Code P0708 GMC - Transmission Range Switch Circuit High Voltage
P0708 GMC Code - Transmission Range Switch Circuit High Voltage

Common Causes of P0708 GMC

  1. Faulty transmission range switch
  2. Damaged wiring or connectors in the circuit
  3. Corrosion or water damage to the switch
  4. Issues with the vehicle's computer system
  5. Wear and tear over time leading to switch malfunction

Symptoms of P0708 GMC

  1. Difficulty starting the vehicle
  2. Incorrect gear selection on the dashboard display
  3. Harsh shifting between gears
  4. Engine stalling when coming to a stop
  5. Inability to shift out of park

How to Fix P0708 GMC

  1. Use a diagnostic scanner to confirm the P0708 code and identify the specific issue.
  2. Inspect the transmission range switch and its wiring for any visible damage or corrosion.
  3. Replace the transmission range switch if found faulty, ensuring proper installation and connection.
  4. Clear the code from the vehicle's computer system and test the switch to ensure proper operation.
  5. If the problem persists, further diagnostic testing may be required to check for underlying electrical issues.

Cost to Fix P0708 GMC

The cost of repairing a P0708 code for a GMC vehicle can vary depending on the extent of the issue and the specific parts needed. In general, the replacement of a transmission range switch can range from $150 to $300, with additional costs for labor. Total repair costs, including parts and labor, could range from $200 to $500. It's important to note that diagnostic time and labor rates vary between auto repair shops, so it's recommended to obtain quotes from multiple sources to get an accurate estimate.

What does this mean?

Tech Notes for P0708 GMC

The Internal Mode Switch (IMS) is mounted to the manual shift shaft detent lever as an assembly. The components of the detent lever/IMS assembly cannot be individually serviced. When the IMS needs replacing, the entire assembly must be replaced.





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Information for Specific GMC Models

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 P0708 GMC Code

1. What are common symptoms of OBDII code P0708 in a GMC related to the Transmission Range Switch Circuit High Voltage?

- Common symptoms include issues with shifting gears, inability to start the vehicle, and the transmission being stuck in a single gear.

2. What are the possible causes of OBDII code P0708 in a GMC?

- The code P0708 can be triggered by a faulty transmission range switch, damaged wiring or connectors in the circuit, or problems with the transmission control module.

3. How can I diagnose the OBDII code P0708 in my GMC?

- Diagnosing the code involves using a scan tool to read the code, checking the transmission range switch for proper operation, inspecting the wiring and connectors for damage, and testing the transmission control module.

4. Can I still drive my GMC with OBDII code P0708 present?

- It is not recommended to drive the vehicle with code P0708 as it can lead to further transmission issues and potential safety hazards. It's best to address the problem promptly.

5. How can I repair OBDII code P0708 in my GMC?

- Repairing the code may involve replacing the transmission range switch, repairing or replacing damaged wiring/connectors, or reprogramming the transmission control module.

6. Are there any DIY tips for fixing OBDII code P0708 in a GMC?

- While some simple checks like inspecting for loose connections or damaged wires can be done DIY, it is recommended to seek professional help for accurate diagnosis and repair of the issue.

7. How much does it typically cost to fix OBDII code P0708 in a GMC?

- The cost of fixing code P0708 can vary depending on the specific cause of the issue, but it may range from a couple of hundred dollars for simpler repairs to over a thousand dollars for more complex fixes.

8. Can a faulty transmission range switch cause OBDII code P0708 in a GMC?

- Yes, a faulty transmission range switch is a common cause of OBDII code P0708 in a GMC, as it can lead to high voltage readings in the circuit.

9. Will resetting the OBDII code P0708 in my GMC make it go away permanently?

- Resetting the code may temporarily clear the error, but if the underlying issue causing the code is not addressed, it is likely to reappear.

10. Is it necessary to get the transmission range switch from the dealership for OBDII code P0708 repair in a GMC?

- While getting the part from the dealership is an option, aftermarket or OEM equivalent parts may also be suitable for repairing OBDII code P0708 in a GMC.

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