Q: How do I fix this? 2002 Hyundai xg350 Transmission Control Relay Always On: I replaced the TCM, no fuses are blown. Still broken.

asked by on August 13, 2017

How do I fix this? 2002 Hyundai xg350, Automatic 3.5 V6: Problem is "Transmission Control Relay Always On", Code P1723. I replaced the TCM, no fuses are blown. Still stuck in 3rd gear and jerks hard when placed in reverse. Fuses look okay, not black or separated, look normal but haven't actually tested them with any equipment... pretty sure they're okay though. How do I fix this issue? Thanks.

My car has 190000 miles.
My car has an automatic transmission.

The only way to fix this issue is to go through the test protocol (diagnostic decision tree) in the Hyundai factory service manual. In particular, for this code (P1723) the circuit to and from the module has to be tested and, in the end, if nothing is amiss with the circuit or the TCM, there are other transmission system components that could be faulty, thus causing this code to set. The P1723 test protocol is lengthy and pointless to reproduce here in this small space. If you desire that the problem be pinpointed by a certified mechanic, please request an on-site diagnostic by using YourMechanic’s check engine light diagnostic page. If you have further questions or concerns, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you to get the best possible results.

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