I have a 07 base with 326k on it. Recently I went to drive it and the ABS, brake light and a flashing D came on. It threw a code U0121. I’ve checked all the fuses, tested the battery, alternator and replaced the ABS module. Still the same. I tried jumping port 4 and 9 at the obd port to reset and still nothing. Please help me I’m at my wits end.

 

DTC Troubleshooting for U0121 from the Service Manual may be helpful.