AutoCodes – Cadillac – P2635 Cadillac

P2635 Cadillac Code - Fuel Pump Flow Performance

Quick Answer

The Engine Control Module (ECM) supplies voltage to the fuel pump driver control module when the ECM detects that the ignition is on. Common causes include Faulty Fuel Pump, Fuel Pump harness is open or shorted, Fuel Pump circuit poor electrical connection. 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: P2635 Cadillac indicates Fuel Pump Flow Performance.
Common causes: Common causes include Faulty Fuel Pump, Fuel Pump harness is open or shorted, Fuel Pump circuit poor electrical connection.
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 3,146

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 Apr 14, 2023

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P2635 Cadillac Description

The Engine Control Module (ECM) supplies voltage to the fuel pump driver control module when the ECM detects that the ignition is on. The voltage from the ECM to the fuel pump driver control module remains active for 2 s unless the engine is in crank or run. While this voltage is being received, the fuel pump driver control module closes the ground switch of the fuel pump. The fuel pump driver control module maintains correct fuel pressure based on the information from the fuel pressure sensor and varies the pulse width modulated controlled current to the fuel pump.
The Diagnostic Trouble Code (DTC) will be set when the fuel pump driver control module detects a difference of ± 60 kPa (8.7 PSI) at 400 kPa (58 PSI) request or ±45 kPa (6.5 PSI) at 300 kPa (43.5 PSI) request between the desired fuel pressure and the actual fuel pressure for approximately 10 s.

OBDII Code P2635 Cadillac - Fuel Pump Flow Performance - AutoCodes.com — P2635 Cadillac Code - Fuel Pump Flow Performance

What does this mean?

What are the Possible Causes of the DTC P2635 Cadillac?

Faulty Fuel Pump
Fuel Pump harness is open or shorted
Fuel Pump circuit poor electrical connection
Faulty Fuel Pump Control Module (if applicable)

How to Fix the DTC P2635 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 does this mean?

Code Tech Notes

There is a Factory Service Bulletin for the following Cadillac Models:

- 2015-2018 Cadillac Escalade

If the Diagnostic Trouble Codes (DTC) P2635, U0074, and/or U18A2 are set, it may be found that the actual fuel pressure (low-pressure system) will be reading substantially higher than desired fuel pressure, in this case, the cause of the problem is a loss of communication between Engine Control Module (ECM) and Fuel Pump Control Module (FPCM).

- Diagnose for any communication DTCs set (U0074 would take priority over U18A2 if both set) before addressing DTC P2635.
- If DTC P2635 is not resolved by correcting the communication DTCs, only then should diagnose the DTC P2635.
- It has been found that a communication issue between the FPCM and ECM can potentially induce DTC P2635 and result in a pressure differential between actual and desired fuel system pressures.
- If the actual fuel pressure is substantially higher than desired (10 psi / 70 kPa or more), replacement of the fuel pump control module or fuel system components typically will not resolve this issue.
- If the actual fuel pressure is substantially lower than desired (10 psi / 70 kPa or more), this Factory Service Bulletin would NOT apply. It would be recommended to diagnose low actual fuel pressure.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P2635 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 P2635 Cadillac Code

1. What are the common symptoms of OBDII code P2635 in a Cadillac related to fuel pump flow performance?

Symptoms may include poor engine performance, reduced fuel efficiency, stalling, and difficulty starting the vehicle.

2. What are the possible causes of OBDII code P2635 indicating fuel pump flow performance issues in a Cadillac?

Potential causes include a faulty fuel pump, clogged fuel filter, fuel pressure regulator problems, wiring issues, or a malfunctioning fuel pump control module.

3. How can I diagnose the underlying issue causing OBDII code P2635 in my Cadillac related to fuel pump flow performance?

Diagnosis typically involves checking the fuel pump operation, inspecting the fuel filter, testing fuel pressure, examining the wiring and connectors, and scanning for any other related trouble codes.

4. Can a dirty fuel filter trigger OBDII code P2635 in a Cadillac?

Yes, a clogged or dirty fuel filter can restrict fuel flow, leading to fuel pump performance issues and triggering code P2635.

5. Is it safe to continue driving my Cadillac with OBDII code P2635 related to fuel pump flow performance?

It is not recommended to drive the vehicle with this code present, as it can lead to further damage to the fuel system and potential safety risks.

6. How can I repair OBDII code P2635 in a Cadillac indicating fuel pump flow performance problems?

Repair options may include replacing the fuel pump, cleaning or replacing the fuel filter, addressing wiring issues, or repairing/replacing the fuel pump control module.

7. Can a DIY enthusiast perform the necessary repairs for OBDII code P2635 in a Cadillac?

Depending on your mechanical skills and access to tools, some repairs related to code P2635 can be performed by DIY enthusiasts. However, it's always recommended to consult a professional mechanic for accurate diagnosis and repair.

8. Will resetting the OBDII system clear code P2635 in a Cadillac?

Resetting the OBDII system may temporarily clear the code, but it will likely reappear if the underlying issue causing the fuel pump flow performance problem is not addressed.

9. How important is it to address OBDII code P2635 in a Cadillac promptly?

It's crucial to address code P2635 promptly to prevent potential fuel system damage, poor vehicle performance, and safety risks associated with fuel delivery issues.

10. Can extreme weather conditions impact the occurrence of OBDII code P2635 in a Cadillac?

Extreme weather conditions, especially extreme heat, can sometimes exacerbate fuel pump performance issues and contribute to triggering code P2635 in a Cadillac.