Patriot Transmission Nightmare: TCU Failure Warning Signs

I faced similar transmission control issues with my 2012 Compass diesel. Having some experience with transmission problems, I can share what worked in my case. The symptoms matched yours exactly, gear slipping, rough shifting, and the transmission control module eventually failed completely. The car computer showed multiple fault codes pointing to the control unit. After thorough transmission diagnosis at my workshop, they confirmed the automatic gearbox issues were caused by a defective control module. The repair involved replacing the entire transmission control unit, which solved all the symptoms. Total cost was around 1000 Euro including programming and installation. To provide more specific advice for your situation, could you share: Current mileage on your Patriot, When did symptoms first appear, Any previous transmission repairs, Specific fault codes shown This information would help determine if your case matches the pattern I experienced with my vehicle.

Last service was at 93200 KM about 2 months ago. The automatic gearbox symptoms started appearing right after that service. The automotive ECU is showing code P0700 now, but initially there were no fault codes present. During the last service they did a transmission fluid change. Nothing else was done to the gearbox system before. The transmission issues came suddenly while driving on the highway at normal operating temperature. The car computer first showed a warning light, then shortly after the gearbox went into limp mode. I checked my service records and no previous gearbox repairs were done since I bought the car with 45000 KM in 2017.

Based on the timing of your symptoms starting right after the transmission fluid service, we should look beyond just the control module. When I had my Compass serviced, a similar situation occurred. While my electronic issues did ultimately stem from a faulty transmission control unit, the fluid change revealed underlying problems. P0700 is a general transmission fault code that the automotive ECU generates when it detects a transmission system problem. In my case, incorrect fluid levels after service triggered initial warnings before the actual control module failure became apparent. I recommend having the workshop check: 1. Fluid level and quality, improper filling after service can cause similar symptoms 2. Transmission control module connections, servicing can disturb wiring 3. Transmission pressure, could indicate internal wear exposed by the fluid change My transmission problems started similarly but worsened gradually. The sudden onset of your issues after service suggests checking these basic items before concluding its a control module failure like mine was. Worth having these checked while the transmission diagnosis is done. Might save you the cost of replacing parts unnecessarily.

Thank you for sharing those additional details about your case. The timing of my gearbox issues after the fluid service definitely raises similar concerns. Having dealt with transmission repair extensively, I plan to first have them verify the fluid level and quality before jumping to conclusions about the transmission control unit. The P0700 code matches what others experienced with TCU problems, but given the service timing, I will request they perform a complete transmission diagnosis focusing on: 1. Proper fluid fill levels 2. Wiring integrity 3. Pressure testing 4. Control module testing Will update once the workshop completes their evaluation. The automotive ECU codes and symptoms align with several potential root causes, so systematic troubleshooting seems the best approach. Need to rule out service-related issues before investing in costly transmission control components. Thanks for helping narrow down the investigation path. Hoping its just a fluid level issue rather than facing a full TCU replacement like you experienced.