AutoCodes – Cadillac – P0687 Cadillac

P0687 Cadillac Code - Engine Control Module Power Relay Control Circuit High

Quick Answer

The powertrain relay is a normally open relay. Common causes include Weak battery, Low voltage while cranking, Faulty Engine Control Module (ECM) power relay. 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: P0687 Cadillac indicates Engine Control Module Power Relay Control Circuit High.
Common causes: Common causes include Weak battery, Low voltage while cranking, Faulty Engine Control Module (ECM) power relay.
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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 2,038

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 Jul 18, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0687 Cadillac Description

The powertrain relay is a normally open relay. The relay armature is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the armature contact at all times. The Engine Control Module (ECM) supplies the ground path to the relay coil control circuit via an internal integrated circuit called an Output Driver Module (ODM). The ODM output control is configured to operate as a low side driver for the powertrain relay. The ODM for the powertrain relay also incorporates a fault detection circuit, which is continuously monitored by the ECM. When the ECM commands the powertrain relay ON, ignition 1 voltage is supplied to the ECM, and to several additional circuits.

OBDII Code P0687 Cadillac - Engine Control Module Power Relay Control Circuit High - AutoCodes.com — P0687 Cadillac Code - Engine Control Module Power Relay Control Circuit High

What does this mean?

What are the Possible Causes of the DTC P0687 Cadillac?

Weak battery
Low voltage while cranking
Faulty Engine Control Module (ECM) power relay
ECM power relay harness is open or shorted
ECM power relay circuit poor electrical connection
Blown ECM fuse
Faulty ECM

How to Fix the DTC P0687 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 P0687 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.

Need more information about the P0687 Cadillac code?

Need more information on how to fix the P0687 Cadillac code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0687 Cadillac code diagnosed by a professional: Find a repair shop in your area

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 P0687 Cadillac Code

1. What are the common symptoms of OBDII code P0687 in a Cadillac?

- Common symptoms include engine stalling, rough idling, poor acceleration, and difficulty starting the vehicle.

2. What can cause the OBDII code P0687 to trigger in a Cadillac?

- The code P0687 is typically triggered by a faulty engine control module power relay or issues with the power relay control circuit.

3. How can I diagnose the cause of OBDII code P0687 in my Cadillac?

- A professional diagnostic scan tool can help pinpoint the exact cause by testing the power relay and related circuits for proper functionality.

4. Can a bad battery or alternator cause the OBDII code P0687 in a Cadillac?

- Yes, a weak battery or failing alternator can sometimes cause voltage irregularities that trigger the P0687 code.

5. What is the recommended repair for OBDII code P0687 in a Cadillac?

- The recommended repair is to replace the faulty engine control module power relay or repair any issues with the power relay control circuit.

6. Are there any DIY tips for fixing the OBDII code P0687 in a Cadillac?

- DIY enthusiasts can check the power relay connections for corrosion, ensure proper grounding, and inspect for any visible damage before replacing the relay.

7. Is it safe to drive my Cadillac with the OBDII code P0687 present?

- It is not recommended to drive the vehicle with the P0687 code present as it can lead to performance issues and potential further damage to the engine control module.

8. Can resetting the OBDII code P0687 in a Cadillac make it go away permanently?

- Resetting the code may temporarily clear the warning light, but if the underlying issue is not addressed, the code is likely to return.

9. How much does it typically cost to repair OBDII code P0687 in a Cadillac?

- The cost of repairing the P0687 code can vary depending on the specific issue, but it generally ranges from $100 to $300 for parts and labor.

10. Will OBDII code P0687 affect the emissions of my Cadillac?

- Yes, the P0687 code can affect the emissions system of the vehicle, potentially leading to increased emissions and failing emissions tests.

Discuss the causes and fixes for P0687 Cadillac OBDII Code

Submit a New Comment

Code P0687 Cadillac comments

No comments found for this page.

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.