AutoCodes – Cadillac – P0878 Cadillac

P0878 Cadillac Code - Transmission Fluid Pressure Switch 4 Circuit High Voltage

Quick Answer

The Transmission Fluid Pressure (TFP) switch 4 is part of the Transmission Control Solenoid Valve Assembly which has no serviceable parts. Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty Transmission Control Solenoid Valve Assembly. 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: P0878 Cadillac indicates Transmission Fluid Pressure Switch 4 Circuit High Voltage.
Common causes: Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty Transmission Control Solenoid Valve Assembly.
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.

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Code Popularity 453

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 03, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0878 Cadillac Description

The Transmission Fluid Pressure (TFP) switch 4 is part of the Transmission Control Solenoid Valve Assembly which has no serviceable parts. The Transmission Control Module (TCM) supplies a signal circuit to the TFP switch 4. The TFP switch 4 has an internal case ground. TFP switch 4 is normally closed or LOW. When oil pressure is present at the TFP switch 4, the switch is open or HIGH. The normal LOW pressure control solenoid 5 controls pressure to the 1-2-3-4 clutch regulator valve. The TCM monitors the TFP switch 4 to determine the position of the 1-2-3-4 clutch regulator valve. When the 1-2-3-4 clutch is commanded OFF, pressure is present on the TFP switch 4. When the 1-2-3-4 clutch is commanded ON, the 1-2-3-4 clutch regulator valve moves and pressure to the TFP switch 4 is exhausted through the 1-2-3-4 clutch regulator valve. The Diagnostic Trouble Code (DTC) will be set when the TCM detects that the TFP switch 4 signal voltage remains HIGH after the 1-2-3-4 clutch transitions from a LOW pressure state to a HIGH pressure state. The TCM counts each incident. The DTC sets when 8 counts are accumulated.

OBDII Code P0878 Cadillac - Transmission Fluid Pressure Switch 4 Circuit High Voltage - AutoCodes.com — P0878 Cadillac Code - Transmission Fluid Pressure Switch 4 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0878 Cadillac?

Low transmission fluid level
Dirty transmission fluid
Faulty Transmission Control Solenoid Valve Assembly
Transmission Control Solenoid Valve Assembly harness is open or shorted
Transmission Control Solenoid Valve Assembly circuit poor electrical connection

How to Fix the DTC P0878 Cadillac?

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 P0878 Cadillac 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.

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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 P0878 Cadillac Code

1. What are some common symptoms of OBDII code P0878 in a Cadillac?

The common symptoms of OBDII code P0878 in a Cadillac include harsh shifting, transmission slipping, decreased fuel efficiency, and the transmission going into limp mode.

2. What causes the OBDII code P0878 in a Cadillac related to the Transmission Fluid Pressure Switch 4 Circuit High Voltage?

The P0878 code in a Cadillac is typically caused by issues with the transmission fluid pressure switch 4 circuit, such as a faulty pressure switch, damaged wiring or connectors, low transmission fluid level, or a malfunctioning transmission control module.

3. How can I diagnose the OBDII code P0878 in my Cadillac?

To diagnose the P0878 code in a Cadillac, you can use an OBDII scanner to read the trouble codes, inspect the transmission fluid level and condition, check the wiring and connectors related to the pressure switch, and perform a thorough visual inspection of the transmission components.

4. What are the repair options for fixing the OBDII code P0878 in a Cadillac?

Repair options for addressing the P0878 code in a Cadillac may include replacing the transmission fluid pressure switch, repairing or replacing damaged wiring or connectors, topping up the transmission fluid, and resetting the trouble codes using an OBDII scanner.

5. Can I drive my Cadillac with the OBDII code P0878 present?

It is not recommended to drive your Cadillac with the P0878 code present, as it can lead to further damage to the transmission system and potentially unsafe driving conditions. It is best to address the issue promptly to prevent more severe problems.

6. How much does it cost to repair the OBDII code P0878 in a Cadillac?

The cost of repairing the P0878 code in a Cadillac can vary depending on the underlying cause of the issue, the labor rates of the repair shop, and the cost of any necessary parts. It is advisable to get a few quotes from different mechanics to compare prices.

7. Will resetting the trouble codes make the OBDII code P0878 go away permanently?

Simply resetting the trouble codes using an OBDII scanner may temporarily clear the P0878 code, but if the underlying issue is not addressed and repaired, the code is likely to reappear once the problem resurfaces. It's essential to diagnose and fix the root cause of the code.

8. Is the OBDII code P0878 a serious issue in a Cadillac?

The P0878 code in a Cadillac should be taken seriously as it indicates a problem with the transmission fluid pressure switch circuit, which can affect the proper functioning of the transmission system. Ignoring the code may lead to more significant transmission issues over time.

9. Can I repair the OBDII code P0878 in my Cadillac by myself?

While some DIY enthusiasts may have the skills to address the P0878 code in a Cadillac, it is generally recommended to consult a professional mechanic for proper diagnosis and repair. Transmission systems are complex, and incorrect repairs can lead to more significant problems.

10. How can I prevent the OBDII code P0878 from occurring in my Cadillac in the future?

To prevent the recurrence of the P0878 code in your Cadillac, it is essential to perform regular maintenance on the transmission system, including checking the fluid level, inspecting for leaks, and addressing any issues promptly to avoid more extensive repairs.