Introduction:

The P0985 diagnostic trouble code (DTC) signifies a problem within the control circuit of Shift Solenoid (SS) 5, as detected by the Transmission Control Module (TCM). This code indicates that the TCM has registered a voltage reading in the SS5 control circuit that is below the expected threshold. Addressing this issue promptly is crucial to prevent potential transmission damage and ensure optimal vehicle performance.

Comprehensive Table: P0985 - Shift Solenoid (SS) 5

Category Description Potential Impact
Definition Shift Solenoid (SS) 5 Control Circuit Low Voltage (TCM). The TCM has detected a lower-than-expected voltage in the SS5 control circuit. Malfunctioning transmission shifting, potential damage to transmission components, reduced fuel efficiency.
Location Shift Solenoid 5 is located inside the transmission, typically within the valve body. Access requires dropping the transmission pan and, in some cases, removing the valve body.
Function SS5 controls the hydraulic pressure that affects the engagement of specific gears within the transmission. Incorrect gear ratios, harsh shifting, failure to shift into certain gears.
Possible Causes 1. Short to ground in the SS5 control circuit wiring. 2. Faulty Shift Solenoid 5. 3. Damaged TCM. 4. Corroded or loose connectors. 5. Open circuit in the SS5 control circuit wiring. 6. Low transmission fluid level. 7. Internal transmission damage. Erratic shifting, transmission slipping, complete transmission failure, Check Engine Light illumination.
Symptoms 1. Check Engine Light illumination. 2. Transmission stuck in a particular gear. 3. Harsh or erratic shifting. 4. Transmission slipping. 5. Reduced fuel efficiency. 6. Transmission fails to shift. 7. Limp mode (limited vehicle speed). Vehicle may be undrivable or experience significantly reduced performance.
Diagnostic Steps 1. Scan for DTCs and document freeze frame data. 2. Inspect wiring and connectors related to SS5. 3. Test SS5 solenoid resistance. 4. Check transmission fluid level and condition. 5. Perform a TCM output test. 6. Check for any transmission mechanical problems. Pinpointing the root cause of the low voltage condition.
Common Mistakes 1. Replacing the shift solenoid without properly diagnosing the root cause. 2. Overlooking wiring issues or connector problems. 3. Failing to check transmission fluid level and condition. 4. Incorrectly interpreting diagnostic data. Unnecessary repairs and continued problems.
Related Codes P0986 (SS5 Control Circuit High), P0750-P0770 (General Shift Solenoid Codes), P0962-P0970 (Pressure Control Solenoid Codes). Understanding the broader context of transmission-related issues.
Tools Required 1. OBD-II scanner. 2. Multimeter. 3. Wiring diagram for the specific vehicle. 4. Socket set and wrenches. 5. Transmission fluid. Accurate diagnosis and repair.
Repair Procedures 1. Repair or replace damaged wiring. 2. Replace faulty Shift Solenoid 5. 3. Replace damaged TCM (requires programming). 4. Clean or replace corroded connectors. 5. Add transmission fluid to the correct level. 6. Repair or replace damaged transmission components. Restoring proper transmission function.

Detailed Explanations:

Definition: Shift Solenoid (SS) 5 Control Circuit Low Voltage (TCM) indicates that the Transmission Control Module (TCM) has detected a voltage in the control circuit of Shift Solenoid 5 that is below the expected or programmed threshold. The TCM monitors the electrical signals to and from the shift solenoids to ensure they are functioning correctly. When the voltage drops below a specific level, the P0985 code is triggered.

Location: Shift Solenoid 5 is located inside the transmission, typically within the valve body. The valve body is a complex assembly of channels and valves that directs hydraulic fluid to different parts of the transmission to engage specific gears. Accessing the shift solenoids requires removing the transmission pan and, in some cases, the valve body itself.

Function: Shift Solenoid 5 plays a crucial role in controlling the hydraulic pressure that activates specific gears within the transmission. It acts as an electrically controlled valve that opens or closes in response to signals from the TCM. By regulating the flow of hydraulic fluid, SS5 helps the transmission shift smoothly and efficiently between gears.

Possible Causes: The P0985 code can be triggered by a variety of issues, including:

  1. Short to Ground in the SS5 Control Circuit Wiring: A short to ground occurs when the wiring in the SS5 control circuit comes into contact with a metal part of the vehicle's chassis, creating an unintended path for electricity to flow. This can cause the voltage in the circuit to drop below the acceptable level.
  2. Faulty Shift Solenoid 5: The shift solenoid itself may be defective, causing it to draw excessive current or fail to respond properly to signals from the TCM.
  3. Damaged TCM: A faulty Transmission Control Module (TCM) can send incorrect signals to the shift solenoid or misinterpret the feedback it receives, leading to the P0985 code.
  4. Corroded or Loose Connectors: Corroded or loose connectors in the SS5 control circuit can increase resistance and reduce the voltage reaching the solenoid.
  5. Open Circuit in the SS5 Control Circuit Wiring: An open circuit means there is a break in the wiring, preventing the flow of electricity to the shift solenoid.
  6. Low Transmission Fluid Level: Low transmission fluid can cause problems with hydraulic pressure, which can affect the operation of the shift solenoids.
  7. Internal Transmission Damage: Internal damage within the transmission, such as worn clutches or damaged valve body components, can indirectly affect the operation of the shift solenoids and trigger the P0985 code.

Symptoms: The symptoms associated with the P0985 code can vary depending on the severity of the problem and the specific vehicle. Common symptoms include:

  1. Check Engine Light Illumination: The Check Engine Light (CEL) will typically illuminate to alert the driver of a problem.
  2. Transmission Stuck in a Particular Gear: The transmission may be unable to shift out of a specific gear.
  3. Harsh or Erratic Shifting: The transmission may shift roughly or unpredictably.
  4. Transmission Slipping: The transmission may slip, causing a loss of power and acceleration.
  5. Reduced Fuel Efficiency: The transmission problem can lead to decreased fuel economy.
  6. Transmission Fails to Shift: The transmission may completely fail to shift between gears.
  7. Limp Mode (Limited Vehicle Speed): The TCM may activate limp mode, limiting vehicle speed to protect the transmission from further damage.

Diagnostic Steps: Diagnosing the P0985 code requires a systematic approach:

  1. Scan for DTCs and Document Freeze Frame Data: Use an OBD-II scanner to retrieve all stored DTCs and record the freeze frame data associated with the P0985 code. This data can provide valuable clues about the conditions that were present when the code was triggered.
  2. Inspect Wiring and Connectors Related to SS5: Carefully inspect the wiring and connectors leading to and from the Shift Solenoid 5 for any signs of damage, corrosion, or looseness.
  3. Test SS5 Solenoid Resistance: Use a multimeter to measure the resistance of the Shift Solenoid 5. Compare the reading to the manufacturer's specifications. A reading outside the specified range indicates a faulty solenoid.
  4. Check Transmission Fluid Level and Condition: Check the transmission fluid level and condition. Low or contaminated fluid can contribute to transmission problems.
  5. Perform a TCM Output Test: Some advanced scan tools can perform a TCM output test, which allows you to activate the shift solenoids and monitor their response.
  6. Check for any Transmission Mechanical Problems: If the electrical components appear to be functioning correctly, investigate for potential mechanical problems within the transmission.

Common Mistakes: Several common mistakes can hinder the diagnostic process:

  1. Replacing the shift solenoid without properly diagnosing the root cause: Replacing the solenoid without addressing the underlying issue may only provide a temporary fix.
  2. Overlooking wiring issues or connector problems: Wiring and connector problems are often the cause of electrical issues, so it's crucial to inspect them thoroughly.
  3. Failing to check transmission fluid level and condition: Low or contaminated fluid can contribute to transmission problems.
  4. Incorrectly interpreting diagnostic data: Misinterpreting the data from the scan tool or multimeter can lead to incorrect diagnoses and unnecessary repairs.

Related Codes: Understanding related codes can provide a broader context for the problem:

  • P0986 (SS5 Control Circuit High): Indicates a voltage that is higher than expected.
  • P0750-P0770 (General Shift Solenoid Codes): These codes relate to other shift solenoids within the transmission.
  • P0962-P0970 (Pressure Control Solenoid Codes): These codes relate to pressure control solenoids, which also affect transmission shifting.

Tools Required:

  1. OBD-II Scanner: To retrieve and clear DTCs.
  2. Multimeter: To measure voltage, resistance, and continuity.
  3. Wiring Diagram for the Specific Vehicle: To identify the correct wires and connectors.
  4. Socket Set and Wrenches: To remove and install components.
  5. Transmission Fluid: To replenish fluid levels after repairs.

Repair Procedures: The repair procedures will depend on the root cause of the P0985 code:

  1. Repair or Replace Damaged Wiring: Repair any damaged wiring by splicing in new sections of wire or replacing the entire harness.
  2. Replace Faulty Shift Solenoid 5: If the solenoid is faulty, replace it with a new one.
  3. Replace Damaged TCM (Requires Programming): If the TCM is damaged, replace it with a new or refurbished unit. The new TCM will likely need to be programmed to the vehicle.
  4. Clean or Replace Corroded Connectors: Clean corroded connectors with a wire brush or replace them with new connectors.
  5. Add Transmission Fluid to the Correct Level: Add transmission fluid to the correct level according to the vehicle manufacturer's specifications.
  6. Repair or Replace Damaged Transmission Components: If internal transmission damage is present, the transmission may need to be rebuilt or replaced.

Frequently Asked Questions:

  • What does the P0985 code mean? The P0985 code indicates a low voltage condition in the control circuit of Shift Solenoid 5, as detected by the TCM. This means the TCM is not receiving the expected voltage signal from or for the SS5.

  • Can I drive my car with a P0985 code? Driving with a P0985 code is not recommended as it can lead to further transmission damage. It's best to have the problem diagnosed and repaired as soon as possible.

  • How do I fix the P0985 code? Fixing the P0985 code requires diagnosing the root cause, which could be a faulty shift solenoid, damaged wiring, a faulty TCM, or other transmission problems. Once the cause is identified, the appropriate repair can be performed.

  • Is the P0985 code serious? Yes, the P0985 code is a serious issue as it can lead to transmission damage and affect vehicle drivability. Prompt diagnosis and repair are essential.

  • How much does it cost to fix a P0985 code? The cost to fix a P0985 code can vary depending on the cause of the problem and the labor rates in your area. A simple wiring repair might cost a few hundred dollars, while replacing the TCM or rebuilding the transmission could cost several thousand.

Conclusion:

The P0985 code, indicating a low voltage condition in the Shift Solenoid 5 control circuit, signals a potentially serious issue affecting transmission performance. A methodical diagnostic approach, focusing on wiring, connectors, the solenoid itself, and the TCM, is crucial for accurate identification and effective repair to prevent further transmission damage.