AutoCodesBuick – B2503 Buick

B2503 Buick Code - Park Relay Shorted To Battery

Quick Answer

When transaxle is in Park, Platform Zone Module (PZM) controls park relay output low to enable Brake Transaxle Shift Interlock (BTSI). Common causes include Faulty Park Relay, Park Relay harness is open or shorted, Park Relay 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
B2503 Buick indicates Park Relay Shorted To Battery.
Common causes
Common causes include Faulty Park Relay, Park Relay harness is open or shorted, Park Relay 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 586
How popular is this code, among other codes? Low
Table of contents Created and updated by William Orellana on Dec 16, 2019
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Code B2503 Buick Description

When transaxle is in Park, Platform Zone Module (PZM) controls park relay output low to enable Brake Transaxle Shift Interlock (BTSI). PZM will continuously monitor this voltage at PZM. The Diagnostic Trouble Code (DTC) B2503 will set when park relay output is active and PZM determines output is high for 2 consecutive monitoring cycles. DTC B2503 will clear when park relay output is active and PZM determines output is low for 2 monitoring cycles.
OBDII Code B2503 Buick - Park Relay Shorted To Battery - AutoCodes.com
B2503 Buick Code - Park Relay Shorted To Battery

What are the Possible Causes of the DTC B2503 Buick?

  • Faulty Park Relay
  • Park Relay harness is open or shorted
  • Park Relay circuit poor electrical connection
  • Faulty Platform Zone Module (PZM)

How to Fix the DTC B2503 Buick?

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 B2503 Buick 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 B2503 Buick Code

1. What does the OBDII code B2503 mean on a Buick?

The code B2503 indicates that the park relay circuit is shorted to the battery, meaning there is an electrical issue where the relay is receiving power when it shouldn't.

2. What are common symptoms of code B2503 in a Buick?

Symptoms may include the inability to shift out of park, malfunctioning parking lights, a drained battery, or dashboard warning lights.

3. What causes the B2503 code in a Buick?

The most common causes are damaged wiring, a faulty park relay, a short circuit in the electrical system, or a malfunctioning body control module (BCM).

4. Can a faulty body control module cause the B2503 code?

Yes, a malfunctioning BCM can send incorrect signals, leading to the park relay being shorted to the battery.

5. How do I diagnose the B2503 code on my Buick?

Start by inspecting the park relay and its wiring for damage or corrosion. Use a multimeter to check for shorts or continuity issues in the circuit.

6. Can the B2503 code drain my battery?

Yes, if the park relay is continuously powered due to the short, it can cause a parasitic drain on the battery.

7. How can I fix the B2503 code on my Buick?

Repairs may involve replacing the faulty park relay, repairing or replacing damaged wiring, or reprogramming or replacing the BCM if needed.

8. Is the B2503 code specific to Buick vehicles?

No, the B2503 code can appear on other vehicles, but its troubleshooting and repair steps may vary depending on the manufacturer.

9. Can I drive my Buick with the B2503 code active?

It’s not recommended, as the issue may prevent shifting out of park or cause electrical problems that could worsen over time.

10. How much does it cost to repair a B2503 code on a Buick?

Repair costs vary but typically range from $100 to $500 depending on whether the issue is with the relay, wiring, or BCM.

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