Engine speed measurement is available on the display screens of the electronic service tool (ECAP or ET)
6V3121 Multitach Group
The 6V3121 Multitach Group can measure engine speed from a magnetic pickup on the flywheel housing. It also has the ability to measure engine speed from visual engine parts in rotation.
Special Instruction, SEHS7807 is with the 6V3121 Multitach Group and gives instructions for the test procedure.
The 1U6602 Tachometer Group is a phototach for general use. The 1U6602 Tachometer Group is a phototach only and reads only the basic input frequency (1 pulse per revolution per piece of reflective tape) on any visible rotating part. The 1U6602 Tachometer Group does not replace the 6V3121 Multitach Group.
Special Instruction, SEHS8854 is with the 1U6602 Tachometer Group and gives instructions for its use.
NOTE: Engine speed measurement can be set with the electronic service tool. Refer to 3100 HEUI Diesel Truck Engine Electronic Troubleshooting SENR6566, for Engine Speed/Timing Calibration.