I’ve been trying to get the heated wheel to work on my 03 for about 2 years now. I’ve tried 3 wheel ecus, 2 wheel switches and have put in a new feed from the fuse box. I now have heat on the wheel, but it’s now on permanently on unless I remove the power. This trying my patience. I’m so close now
The energised steering wheel relay provides a feed to fuse 29. Fuse 29 (C0582) is connected to the rotary coupler (C0374) by a GB wire, allowing the rotary coupler to provide a feed to the heated steering wheel ECU C1948 ) on an N wire. The steering wheel ECU is earthed via the rotary coupler on an R then N wire.
And the wiring diagram;
If it won't turn off to maintain a certain temp then the temperature switch in the wheel must be faulted somewhere. If it won't turn off when you shut the truck off either the relay contact is welded closed or its not being powered from a switched ignition source.