Here is the transmission wiring diagrams and there is no TCM control relay. I would think the problem is with the TCM itself, did you check the power ground and fuses?
This guide can help:
https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester
The fault codes you provided indicate potential issues with the Transmission Control Module (TCM), Engine Control Module (ECM), torque converter clutch, communication between modules, and low fluid pressure in the transmission. These issues could be related to one another or separate problems. Troubleshooting these codes will require a systematic approach, and I'll outline some general steps to help you get started:
Check Fluid Level and Condition: Low transmission fluid level or dirty/contaminated fluid can cause various transmission-related issues. Ensure the transmission fluid is at the correct level and looks clean and red. If the fluid is dark or has a burnt smell, it may need to be changed.
Inspect for Leaks: Check for any leaks in the transmission system that could be causing low fluid pressure. Leaks can lead to inadequate lubrication and pressure, affecting transmission performance.
Verify Battery and Connections: Some of the fault codes could be related to electrical issues. Check the vehicle's battery health and the connections to the TCM and ECM for any corrosion or loose connections.
Inspect Wiring and Connectors: Look for damaged or corroded wiring and connectors related to the TCM, ECM, and transmission components. Damaged wires or poor connections can cause communication problems and affect the performance of these modules.
TCM Power Relay: The P0890 code suggests an issue with the TCM power relay sense circuit. Locate the TCM relay, which is typically in the fuse/relay box under the hood or inside the cabin. Refer to the vehicle's service manual or repair guide to find its exact location.
Scan Tool Diagnostics: Use a professional-grade scan tool to access more specific diagnostic information. Check for any additional codes, freeze frame data, or live data to gather more insights into the problem.
Address Torque Converter Clutch (TCC) Issue: The P0744 code relates to the torque converter clutch. It could be a wiring issue, a faulty solenoid, or a problem with the torque converter itself. Further diagnosis will be needed to pinpoint the exact cause.
Check Keep Alive Memory (KAM) Circuit: The P0603 code points to a problem with the ECM's keep-alive memory. It could be an issue with the ECM or related circuits. A thorough inspection is required.
Lost Communication with ECM/PCM: The U0100 code indicates a communication problem between modules. This could be due to a faulty module, wiring issue, or even a software-related problem.
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Tuesday, August 1st, 2023 AT 10:50 AM