AutoCodes – Cadillac – P2603 Cadillac

P2603 Cadillac Code - Auxiliary Coolant Pump Circuit High

Quick Answer

The auxiliary coolant pump and cooling fan system provides a measure of prevention against fuel vaporization due to excessive engine temperatures. Common causes include Faulty Auxiliary Coolant Pump Relay, Blocked pump control passage, Faulty Auxiliary Coolant Pump. 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: P2603 Cadillac indicates Auxiliary Coolant Pump Circuit High.
Common causes: Common causes include Faulty Auxiliary Coolant Pump Relay, Blocked pump control passage, Faulty Auxiliary Coolant Pump.
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 1,186

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 Jan 19, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P2603 Cadillac Description

The auxiliary coolant pump and cooling fan system provides a measure of prevention against fuel vaporization due to excessive engine temperatures. The Engine Control Module (ECM) commands the auxiliary or after boil coolant pump ON when the engine coolant temperature exceeds a calibrated value after engine shut down. The ECM applies ground to the coil side of the auxiliary pump relay. This energizes the coil and applies voltage directly to the pump motor through the switch side of the relay. When the auxiliary coolant pump is activated, coolant is drawn from radiator and pumped into the engine through a tee in the engine coolant inlet pipe. As the colder temperature coolant is drawn into the engine warmer coolant is expelled from the engine and back to the radiator. Removing high temperature coolant from the engine after shut down helps prevent vaporization of the fuel that remains in the fuel injectors and fuel rail during a hot soak.

OBDII Code P2603 Cadillac - Auxiliary Coolant Pump Circuit High - AutoCodes.com — P2603 Cadillac Code - Auxiliary Coolant Pump Circuit High

What does this mean?

What are the Possible Causes of the DTC P2603 Cadillac?

Faulty Auxiliary Coolant Pump Relay
Blocked pump control passage
Faulty Auxiliary Coolant Pump
Auxiliary Coolant Pump harness is open or shorted
Auxiliary Coolant Pump circuit poor electrical connection

How to Fix the DTC P2603 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 P2603 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 P2603 Cadillac Code

1. What are the common symptoms of OBDII code P2603 in a Cadillac related to the Auxiliary Coolant Pump Circuit High?

The common symptoms include overheating of the engine, coolant leaks, and potential illumination of the Check Engine Light.

2. What are the possible causes of OBDII code P2603 in a Cadillac?

Possible causes of this code include a faulty auxiliary coolant pump, damaged wiring or connectors in the coolant pump circuit, or issues with the engine control module (ECM).

3. How can I diagnose the OBDII code P2603 in a Cadillac?

Diagnosing this code involves using a scan tool to read the code, inspecting the auxiliary coolant pump and its connections, checking for any visible damage to the wiring, and testing the coolant pump circuit for proper voltage and continuity.

4. Can I drive my Cadillac with the OBDII code P2603 present?

It is not recommended to drive your Cadillac with this code present, as it can lead to engine overheating and potential damage. It is advisable to address the issue promptly.

5. How can I repair OBDII code P2603 in a Cadillac?

Repairing this code may involve replacing the faulty auxiliary coolant pump, repairing or replacing damaged wiring or connectors, or reprogramming the engine control module, depending on the root cause of the issue.

6. Is it safe to continue driving if the Check Engine Light is flashing due to OBDII code P2603?

If the Check Engine Light is flashing, it indicates a severe issue that requires immediate attention. It is recommended to pull over safely and have the vehicle towed to a professional for diagnosis and repair.

7. Can a DIY enthusiast fix OBDII code P2603 in a Cadillac?

Depending on the level of expertise, a DIY enthusiast may be able to address this code by following repair guides and using proper diagnostic tools. However, complex issues may require professional assistance.

8. Will resetting the Check Engine Light resolve OBDII code P2603 in a Cadillac?

Resetting the Check Engine Light will only clear the code temporarily. The underlying issue causing the code will need to be diagnosed and repaired to prevent the code from reappearing.

9. How much does it typically cost to repair OBDII code P2603 in a Cadillac?

The cost of repairing this code can vary depending on the root cause of the issue, parts needed for replacement, and labor costs. It is advisable to obtain quotes from different mechanics for an accurate estimate.

10. Can a malfunctioning auxiliary coolant pump cause other problems in a Cadillac besides triggering OBDII code P2603?

Yes, a malfunctioning auxiliary coolant pump can lead to engine overheating, poor performance, and potential damage to other components in the cooling system if left unresolved.