For Jeep Patriot owners looking to customize their vehicles, cell phone OBD2 scan tools offer a tempting blend of convenience and capability. Apps like Jscan promise users the power to modify settings like tire size and Daytime Running Lights (DRLs) right from their smartphones. However, real-world experiences sometimes diverge from advertised features. This article delves into one user’s encounter with the Jscan app and the challenges faced while attempting to adjust settings on a Jeep Patriot, highlighting potential pitfalls and offering insights for those considering similar modifications using cell phone OBD2 scan tools.
The user initially sought to make two key changes using the Jscan app: recalibrating the tire size setting and altering the DRL configuration on their Jeep Patriot. The goal was to switch the DRL activation from high beams to low beams and sidelights, a common customization for improved aesthetics and potentially reduced glare for oncoming traffic. After applying these modifications through the Jscan app, the user encountered a significant issue the very next day. An engine light illuminated on the dashboard, and the Jeep Patriot entered limp mode, severely restricting engine power and vehicle speed. This immediately raised concerns about the reliability of cell phone OBD2 scan tools for certain modifications, especially concerning critical vehicle systems.
Alt text: Engine light illuminated on car dashboard, indicating potential issues after using cell phone OBD2 scan tool.
Diagnosing the problem, the user identified a P0610 TRANS CONTROL code, pointing towards a transmission control system malfunction. Resolving this issue proved to be a time-consuming process, taking two days to fully clear the engine light and restore normal vehicle operation. The troubleshooting steps involved a somewhat complex procedure: disconnecting the battery, draining residual electrical charge by connecting the disconnected battery cables together (circuit draining), and leaving them disconnected for approximately half an hour. Following reconnection, a sequence of ignition cycling (switching off and on multiple times) and idling the engine was necessary. This process appeared to allow the engine control unit (ECU) to relearn settings and stabilize, suggesting the Jscan modifications had disrupted the vehicle’s computer system.
Further investigation within the Jscan app revealed the extent of the changes made. Navigating to the settings section within the app, the user was able to trace and restore the modified parameters back to their original factory settings. After ensuring all adjustments were reverted, an advanced scan was performed using the cell phone OBD2 scan tool. This scan initially revealed the P0610 code along with three additional codes: B1634, B1630, and B1638, all related to high beam control circuit faults. Crucially, after clearing all codes using the app’s diagnostic function and rescanning, the P0610 limp mode code disappeared. While the high beam related codes persisted, the engine light extinguished after driving the car, and normal driving performance returned, indicating the limp mode issue was resolved by reverting the Jscan modifications and clearing the fault codes.
Alt text: Close-up of OBD2 port in a vehicle, where cell phone OBD2 scan tool adapter is connected for diagnostics.
Seeking clarification, the user contacted the Jscan manufacturer regarding the issues encountered with the Jeep Patriot. The response confirmed that the Jscan app was known to have limitations with tire size adjustments on this particular vehicle model. This highlights a critical point for users of cell phone OBD2 scan tools: compatibility and feature reliability can vary significantly between vehicle makes and models. While these tools offer broad diagnostic and customization capabilities, they are not universally flawless and may have specific limitations.
Currently, despite reverting the problematic Jscan settings, the user’s Jeep Patriot still exhibits the B1633, B1634, and B1638 high and low beam related error codes. Functionally, the vehicle operates normally, albeit with a minor speedometer discrepancy due to the previous tire size adjustment attempt and the high beams activating when low beams are selected. Further experimentation with other Jscan features, such as activating HIDs, also resulted in the reappearance of the engine light and limp mode, reinforcing the issues encountered with modifications beyond basic diagnostics on this specific Jeep Patriot.
Alt text: Jscan app interface on a cell phone, displaying vehicle diagnostic information from OBD2 scan tool.
It’s important to note the user’s Jeep Patriot is equipped with aftermarket HID projector headlights, wired through relays. The relay coils are powered by the original headlight wiring, which then provides 12V power to the HID circuits. This aftermarket lighting setup could be a contributing factor to the error codes and issues experienced. The vehicle’s computer system might be detecting the altered electrical load or resistance introduced by the relays and HID system, leading to the fault codes and sensitivity to modifications attempted through the cell phone OBD2 scan tool.
Considering alternative solutions, the user is contemplating trying the Appcar Diagfca app, another cell phone OBD2 scan tool option popular among Jeep owners. However, the experience with Jscan raises a valid question: will similar issues arise when attempting tire size or DRL modifications using a different app? This highlights the need for caution and thorough research before using cell phone OBD2 scan tools for vehicle modifications. While these tools offer user-friendly interfaces and potentially powerful customization options, understanding their limitations, vehicle compatibility, and the potential risks associated with altering critical vehicle settings is paramount. For Jeep Patriot owners, particularly those with modified electrical systems, proceeding with caution and seeking expert advice may be prudent when using cell phone OBD2 scan tools for modifications beyond basic diagnostics.
