HARNESS AS-ENGINE 2490093 - Caterpillar

Introduction
The 4C6821 Injection Line Speed Pickup Group provides a method of sensing engine speed through the fuel injection lines without disconnecting any of the injection lines. The pickup group can be clamped onto any fuel injection line. The pickup group is then connected to the PH (Photo) input of a 6V2100 Multitach with the cable provided. The multitach then displays the engine speed in R/MIN (rpm). The accuracy of measurement is the same as the original specification for the multitach ( 1 R/MIN). Refer to the NOTE below. Modifications must be made to some earlier 6V2100 Multitachs before speed measurements can be taken accurately. Refer to the topic "Modification of 6V2100 Multitach" for this procedure, and to determine if modifications are necessary.The pickup group can be easily installed on any fuel injection line. The only preparation necessary is the removal of a small amount of paint from the injection line where the pickup group is to be clamped. The injection line speed pickup group can be used either for temporary testing or for permanent installation.* The 4C6821 Pickup Group is a direct replacement for the 6V4950 Injection Line Speed Pickup Group.The 4C6821 Pickup Group differs from the 6V4950 Injection Line Speed Pickup Group only by the inclusion of a switch on the 4C6812 Amplifier and use of the newer 1U9139 Universal Style Pickup. The switch adapts the amplifier for use with the 4C6800 Data Logger Group. When used with the 6V2100 Multitach, the switch should always be in the INJ LINE position.4C6821 Injection Line Speed Pickup Group Components
(1) 1U9139 Pickup. (2) 4C6812 Amplifier.Reference: Special Instructions SMHS7504-01, SEHS7807 and SEHS8224.Modification of 6V2100 Multitach
Check the 6V2100 Multitach;* If there is an "A" at the location shown, no modifications are needed.* If there is no "A", Refer to Special Instruction SEHS8224, entitled "Troubleshooting and Repair of the 6V2100 Multitach", for the update modifications needed.These modifications if needed, must be made to the multitach to achieve the correct accuracy of the speed readings.Optional Items for Use With the 4C6821 Injection Line Speed Pickup Group
(1) 6V2100 Multitach. (2) 6V4190 Autoprogrammer. (3) 5P7366 Power Cable. (4) 6V2198 Extension Cable.The 6V2100 Multitach (1) is a programmable digital tachometer used as the speed readout for the injection line speed pickup group.The 6V4190 Autoprogrammer (2) is an accessory for the 6V2100 Multitach, which provides automatic programming whenever the multitach is powered and when switching between PH (photo) and MAG (magnetic) inputs.The 5P7366 Power Cable (3) is used for connecting 11-40 VDC power to the multitach.The 6V2198 Extension Cable (4) is the photo input extension cable, used for connecting the 6V4950 Pickup Group to the 6V2100 Multitach.Specifications
Adaptability: or use on all non-unit injected Caterpillar diesel engines. Engine Speed Range: 40 to 6000 rpm. Pulses Per Revolution: Use .5 P/Rev (pulses per revolution) for all Caterpillar four stroke diesel engines. Output Signal Amplitude: .75 volts peak minimum. Noise: Less than .4 volts peak. Operating Temperature Range: -23°C to +70°C (-9°F to 158°F). Storage Temperature Range: -40°C to +100°C (-40°F