On the Digitrax website it indicates that the DH165IP chip is the correct one for the S4 engine. I installed one in my Bachmann Alco S4 engine, and it doesn't work correctly. I have no speed control. The engine works as it's supposed to with the dummy chip in place as a DC engine. I have sent the Digitrax chip back to them twice and they've returned it to me twice, but the problem persists. Evidently, they don't try it in an actual S4 engine, but they say they returned the chip to factory settings. Well, the factory settings don't work, and their website is incorrect in indicating this is the proper chip for the S4 engine. I'm very dissatisfied with Digitrax.

Does anyone know which chip will work correctly in the Bachmann Alco S4 engine to convert it from DC to DCC?

Which decoder do I need for a Bachmann Alco S4 DCC ready Switcher engine