AutoCodes – Toyota – P0ADD Toyota

P0ADD Toyota Code - Hybrid Battery Negative Contactor Control Circuit/Open

Quick Answer

The SMRs (System Main Relays) connect and disconnect the high-voltage power supply circuit in accordance with requests from the HV control ECU. Common causes include Faulty System Main Relay, System Main Relay harness is open or shorted, System Main 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: P0ADD Toyota indicates Hybrid Battery Negative Contactor Control Circuit/Open.
Common causes: Common causes include Faulty System Main Relay, System Main Relay harness is open or shorted, System Main 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 2,109

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 Feb 15, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0ADD Toyota Description

The SMRs (System Main Relays) connect and disconnect the high-voltage power supply circuit in accordance with requests from the HV control ECU. To ensure a reliable operation, they consists of a total of 3 relays (1 for the negative side and 2 for the positive side).
To connect, SMR1 and SMR3 turn ON initially. Then, SMR2 turns ON and SMR1 turns OFF. This process protects the circuit from the high-voltage surge current by allowing the limit current to flow via the resistor.
To disconnect, SMR2 and SMR3 turn OFF in that order. The HV control ECU checks that the relays have turned OFF properly.
The HV control ECU monitors the proper operation of the SMRs (CON1, CON2 and CON3) to check for a malfunction.

OBDII Code P0ADD Toyota - Hybrid Battery Negative Contactor Control Circuit/Open - AutoCodes.com — P0ADD Toyota Code - Hybrid Battery Negative Contactor Control Circuit/Open

What does this mean?

What are the Possible Causes of the DTC P0ADD Toyota?

Faulty System Main Relay
System Main Relay harness is open or shorted
System Main Relay circuit poor electrical connection
Faulty HV control ECU

How to Fix the DTC P0ADD Toyota?

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 P0ADD Toyota 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 P0ADD Toyota Code

1. What does the OBDII code P0ADD mean on a Toyota?

P0ADD indicates a problem with the Hybrid Battery Negative Contactor Control Circuit, specifically an open circuit or control malfunction.

2. What are the common symptoms of code P0ADD in a Toyota hybrid?

Symptoms may include the hybrid system warning light, reduced vehicle performance, failure to start, or the inability to switch between EV and hybrid modes.

3. What causes the P0ADD code to appear on a Toyota?

Common causes include a faulty hybrid battery negative contactor, damaged wiring or connectors, a blown fuse, or a malfunctioning hybrid control module.

4. Can I continue driving my Toyota with a P0ADD code?

It is not recommended to drive with this code active, as it may prevent the hybrid battery from functioning properly and could lead to further damage.

5. How is the P0ADD code diagnosed?

A technician will inspect the hybrid battery contactor circuit, check for damaged wiring or loose connections, and test the operation of the hybrid battery negative contactor and related components.

6. What repairs are needed to fix the P0ADD code on a Toyota?

Repairs may include replacing a faulty hybrid battery negative contactor, repairing or replacing damaged wiring, or reprogramming or replacing the hybrid control module if necessary.

7. How much does it cost to fix the P0ADD code on a Toyota?

Repair costs vary depending on the specific issue but can range from $200 to over $1,000, depending on whether wiring repairs or component replacements are needed.

8. Can a dead 12V battery cause the P0ADD code on a Toyota hybrid?

While unlikely, a weak or dead 12V battery can sometimes contribute to hybrid system errors by affecting the control circuits. Itâ€™s worth testing the 12V battery as part of the diagnostic process.

9. Will clearing the P0ADD code fix the issue?

Clearing the code without addressing the root cause will only temporarily remove the warning. The issue will reoccur until the underlying problem is fixed.

10. Can a DIYer fix the P0ADD code on a Toyota hybrid?

DIY repairs are possible if you have experience with hybrid systems and the necessary tools, but due to high-voltage components, professional diagnosis and repair are highly recommended for safety.