A ‘Stop/Start Unavailable Service Stop/Start System’ notification from your Jeep is a warning that the start-stop feature has been disabled. While several factors could trigger the warning, it is often because of a defective auxiliary battery. However, a loose cable connection, electrical issues, engine problems, and extreme weather conditions can also make the system malfunction.
Jeep’s start-stop technology is an automated system that reduces fuel consumption and exhaust emissions. It shuts off the engine when it detects that the vehicle has come to a halt. And only restart it when the driver releases the brake pedal or accelerates.
The technology relies on several components, and the failure of anyone will make the system malfunction. When the system malfunction, it sets off a ‘start-stop unavailable’ warning to notify the driver that the feature has been disabled.
The ‘Stop/Start Unavailable Service Stop/Start System’ warning is mostly triggered by a faulty battery. And it is often because of a faulty auxiliary battery, otherwise known as the backup battery. The battery is mounted under the passenger seat and is used to power vehicle accessories, including the start-stop system.
Since the system repeatedly draws charge from the battery, they have lower resistance. This allows them to deliver high current on demand. But unlike the main battery, auxiliary batteries have a shorter lifespan. Often lasting between two to three years.
Sometimes, the failure of the main battery can also cause the start-stop system to fail. But whichever battery causes the failure, getting a new one is usually the way forward. And you always want to ensure that you get the manufacturer’s recommendation.
Loose cable connections
Loose cable connections can also cause the start-stop system to malfunction. The battery supplies the system with electricity to stay operational. Thus, it must always maintain a stable connection with the battery. Because without a stable connection, the system will malfunction.
Besides a stable battery connection, the vehicle must maintain a solid ground connection. A bad ground connection is enough to cause the start-stop system to malfunction.
The battery and ground connections are often disrupted due to corrosion. With the ground connection, the corrosion on the nut causes it to arc, consequently welding it to the connector.
The solution is to inspect the battery terminal and connectors for corrosion. If there is any, brush it off using a steel brush. This helps to rekindle the connection between the connectors and the battery terminal. You can also improve the ground connection by cleaning the connector and stud down to the bare metal if you notice any sign of corrosion.
A faulty or poor wiring can also cause the system to malfunction. The system uses a network of wires to interact with the necessary vehicle components.
The vehicle wire network can become frail, creating an unstable connection. Or worse, it triggers a sudden electrical spike, which will cause the system to fail, as they are extremely sensitive to the operating voltage. The unstable connections can also cause the start-stop system to stall intermittently.
The solution is to investigate the vehicle wiring to trace the broken wire. You may want to involve a professional, as diagnosing electrical issues can be tricky.
Blown fuse or relay
Vehicle electrical circuits, including the start-stop circuit, are opened and closed by relays and fuses. This is to protect the electrical systems from overloads during a surge. A surge current can cause the fuse or relay to fail. The start-stop system will stall when the fuse or relay protects it fails.
Ordinarily, finding and replacing the defective relay or fuse should bring the system back online.
Besides the battery, some engine components also play a crucial role in the operation of the start-stop system. The starter motor, spark plugs, and fuel system works together to keep the system running.
When the vehicle comes to a halt, the system shuts off the engine by turning off the spark to the ignition and fuel flow to the cylinder. Both features are instantly restored so the starter motor can restart the engine once the driver releases the brake pedal.
Clearly, the repeated stop-and-start cycles during trips will speed up the wear and tear of these components. This is why manufacturers employ the toughest and most durable materials for these parts.
But regardless of how durable these parts are, they will eventually break down. The failure of any of these components will invariably cause the system to fail.
You can avoid engine issues with preventive maintenance. Preventive maintenance helps prolong the engine components and detect issues before they arise. But once the damage is done, you must replace the failed component.
Extreme operating conditions
The battery management system can also disable the start-stop system. It disables the system during extreme weather conditions. A battery performance takes a hit during cold temperatures. While hot temperatures can also shorten their lifespan.
The BMS deactivates some systems during such situations to reduce the battery load. The start-stop system is often one of the systems that get deactivated. Prompting a ‘Stop/Start Unavailable Service Stop/Start System’ message.
The system should become operational once the operating condition returns back to normal. But if it doesn’t, examine the main and auxiliary batteries to check that they are both working.
The electronic start system shuts down the engine to reduce exhaust emissions and fuel consumption.
The system relies on some components, including an auxiliary battery, starter motor, spark plugs, and fuel system. The failure of any of these components will cause the system to fail. But a blown fuse or relay, loose connection, electrical issues, and extreme weather can also cause it to fail.
When the system fails, it triggers a ‘Stop/Start Unavailable Service Stop/Start System’ to notify the driver that the system has been disabled.