Grinding Transmission + Bad Sensor = Wrangler Troubles

I had a similar issue with my 2012 Jeep Cherokee last year. With some basic car repair experience, I initially tried diagnosing it myself. The symptoms matched yours exactly, transmission warning light, limp mode, and grinding during shifts. Using a pressure gauge on the cooling system showed normal readings, but the transmission was still acting up. Took it to my regular workshop where they found the culprit, a faulty wire connection to the transmission oil cooler sensor. The connector had corroded over time, sending incorrect signals to the transmission control unit. They cleaned the connection points, replaced the damaged wiring, and properly sealed the new connector. Total repair cost was 95 Euro, mostly labor. The transmission returned to normal operation immediately after the fix. No parts replacement was needed besides the wiring. Before suggesting more specific solutions, could you share: Current mileage on your Wrangler, When was the last transmission fluid change, Any previous transmission repairs, Are the issues constant or do they come and go This would help determine if your case is similar to what I experienced with the sensor connection.

Last service was done at 35815 KM and my issues started shortly after. The radiator repair shop confirmed a coolant leak near the transmission lines. When they performed leak detection tests, the cooling fan was working normally but the pressure readings were inconsistent. A fellow Wrangler owner suggested checking the transmission cooler connections first before replacing any major components. The grinding noise seems to get worse when the engine is fully warmed up. So far I have only done pressure gauge testing, but no deeper diagnostics yet. Waiting to book an appointment next week to have everything properly checked. Hoping its just a sensor or connection issue like in your case rather than a complete transmission overhaul.

Since you mentioned getting inconsistent pressure readings, I strongly suspect you have the same underlying issue I faced, a wiring problem affecting the transmission sensor system. The symptoms getting worse with heat matches my experience exactly. When my Jeep had this problem, the coolant leak detection also showed irregular readings initially. However, the real issue was the corroded wiring feeding incorrect data to the transmission control unit. The coolant leak near your transmission lines could be causing the same type of connection problems I encountered. Before authorizing major transmission work, have them specifically check: Wiring connections at the transmission oil cooler, Sensor ground points for corrosion, Coolant contamination in the wiring harness area The grinding noise intensifying after warm-up is very similar to what I experienced before the repair. In my case, cleaning and replacing the damaged wiring connections resolved all symptoms, including the erratic pressure readings and transmission behavior. Since your mileage is relatively low at 35815 KM, major internal transmission issues would be unusual. My repair was straightforward once properly diagnosed, and the car has performed flawlessly since fixing those connections. Let us know what the workshop finds during your appointment. A thorough inspection of the sensor and wiring system should reveal if you have the same root cause I encountered.

Thanks for the detailed feedback about the wiring connections. The workshop confirmed they will do a complete check of all transmission sensor connections and wiring during my appointment. The radiator coolant leak seems minor but could definitely be causing those connection issues you mentioned. Since posting, I noticed the grinding gets much worse after driving about 20 minutes once everything is hot. The pressure sensor readings are all over the place according to the cooling system diagnostic report. The transmission slipping has also become more frequent. Will update once they complete the inspection next week. Really hoping its just corroded wiring causing the erratic sensor behavior rather than internal transmission damage. The relatively low mileage makes me optimistic its not a major mechanical problem. Appreciate you sharing your similar experience, gives me a good starting point to discuss with the mechanics.