greenisacolor Posted July 9, 2023 Report Share Posted July 9, 2023 Hello, I am using VR4 link on my dsm and recently swapped the car from 5 speed to automatic. I am using a forced four 100.1 as my standalone TCU, and the TCU requires a tach, speedo and TPS signal from the ECU. Speedo and TPS are outputting fine, but I can't get Tacho to output to the TCU. Previously I was outputting Tach signal to an autometer 5" tach using pin 62 which is Inj Aux 5. I got rid of the autometer tach as I now have the link dash and have wired my TCU to use that same Inj Aux 5 to output tacho signal to the TCU. I have verified the ECU is getting a tach signal, I have tested continuity across the wires and everything checks out. Is this a limitation of the Injector aux driver? Do I need to relocate this to a different aux output? Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 9, 2023 Report Share Posted July 9, 2023 A injector output is low-side drive with no pull-up resistor, possibly your autometer tach had a pull-up resistor built-in and the TCM doesn't. Normal aux outputs have pull-up resistors built-in, Inj auxes and Ign auxes dont. So you could either add an external pull-up resistor into the wiring, or you could move your tacho wire to Aux 2 or 3. The CE light would work fine connected to Inj 5. This is how you would wire an external pull-up: Quote Link to comment Share on other sites More sharing options...
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