AutoCodes – Chevrolet – P0688 Chevrolet

P0688 Chevrolet Code - Electronic Control Module Power Relay Sense Circuit/Open

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: P0688 Chevrolet indicates Electronic Control Module Power Relay Sense Circuit/Open.
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.

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Code Popularity 1,664

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 May 15, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0688 Chevrolet 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 P0688 Chevrolet - Electronic Control Module Power Relay Sense Circuit/Open - AutoCodes.com — P0688 Chevrolet Code - Electronic Control Module Power Relay Sense Circuit/Open

What does this mean?

What are the Possible Causes of the DTC P0688 Chevrolet?

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 P0688 Chevrolet?

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 P0688 Chevrolet 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 P0688 Chevrolet code?

Need more information on how to fix the P0688 Chevrolet code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0688 Chevrolet 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 P0688 Chevrolet Code

1. What are the common symptoms of OBDII code P0688 in a Chevrolet vehicle?

- Common symptoms include rough idling, engine stalling, difficulty starting the vehicle, and decreased fuel efficiency.

2. What does the OBDII code P0688 Chevrolet indicate?

- The code indicates a problem with the Electronic Control Module (ECM) power relay sense circuit, specifically an open circuit.

3. What are some possible causes of the P0688 code in a Chevrolet?

- Possible causes include a faulty ECM power relay, damaged wiring or connectors in the relay circuit, a blown fuse, or a malfunctioning ECM.

4. How can I diagnose the cause of the P0688 code in my Chevrolet vehicle?

- Diagnosis typically involves checking the ECM power relay, inspecting the wiring and connectors for damage, testing the relay circuit for continuity, and verifying proper voltage levels.

5. Can I drive my Chevrolet with the P0688 code present?

- It is not recommended to drive the vehicle with the P0688 code as it can lead to further damage to the ECM and other components. It's best to address the issue promptly.

6. How can I repair the Electronic Control Module power relay sense circuit/open issue in my Chevrolet?

- Repairs may involve replacing the faulty ECM power relay, repairing or replacing damaged wiring or connectors, and resetting the trouble code with an OBDII scanner.

7. Are there any specific tips for preventing the recurrence of the P0688 code in a Chevrolet?

- Regularly inspecting and maintaining the ECM power relay, wiring, and connectors can help prevent the recurrence of the P0688 code. It's also important to address any electrical issues promptly.

8. Can a DIY enthusiast fix the P0688 code issue in a Chevrolet?

- Depending on their skill level and access to tools, a DIY enthusiast may be able to diagnose and repair the P0688 code. However, it's recommended to consult a professional for complex electrical issues.

9. How much does it typically cost to repair the P0688 code in a Chevrolet at a repair shop?

- The cost of repairs for the P0688 code can vary depending on the root cause of the issue, the labor rates of the repair shop, and the cost of replacement parts. It's best to get a quote from a reputable shop.

10. Is it possible for the P0688 code to trigger other trouble codes in a Chevrolet?

- Yes, the P0688 code can sometimes trigger related codes such as P0689 (ECM/PCM Power Relay Sense Circuit Low) or P0690 (ECM/PCM Power Relay Sense Circuit High). It's important to address all relevant codes during diagnosis and repair.