AutoCodes – Pontiac – P0688 Pontiac

P0688 Pontiac 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 Pontiac 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 1,251

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 Pontiac 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 Pontiac - Electronic Control Module Power Relay Sense Circuit/Open - AutoCodes.com — P0688 Pontiac Code - Electronic Control Module Power Relay Sense Circuit/Open

What does this mean?

What are the Possible Causes of the DTC P0688 Pontiac?

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 Pontiac?

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 Pontiac 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 P0688 Pontiac Code

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

- Common symptoms include difficulty starting the vehicle, engine stalling, and potential loss of power to various electrical components.

2. What does the OBDII code P0688 in a Pontiac indicate?

- The code P0688 indicates a problem with the Electronic Control Module (ECM) Power Relay Sense Circuit/Open.

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

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

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

- Diagnosing the issue typically involves checking the ECM power relay, inspecting the wiring and connectors for damage, and testing the ECM for proper functioning.

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

- It is not recommended to drive your vehicle with the P0688 code, as it can lead to engine stalling and potential safety hazards.

6. How can I repair the P0688 code in my Pontiac?

- Repairing the P0688 code may involve replacing the ECM power relay, repairing or replacing damaged wiring or connectors, or replacing the ECM itself.

7. Is it possible to reset the P0688 code in a Pontiac without fixing the underlying issue?

- While you can clear the code using an OBDII scanner, it is important to address the root cause of the problem to prevent it from recurring.

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

- Depending on your skill level and access to tools, you may be able to diagnose and repair the P0688 code yourself. However, seeking professional help is recommended for more complex issues.

9. How much does it cost to repair the P0688 code in a Pontiac?

- The cost of repairing the P0688 code can vary depending on the cause of the issue, the parts needed, and labor costs. It is advisable to obtain quotes from different mechanics or repair shops.

10. How can I prevent the P0688 code from recurring in my Pontiac?

- To prevent the P0688 code from recurring, it is essential to address the underlying issue promptly, perform regular maintenance on your vehicle, and keep an eye out for any signs of electrical problems.