PWM Signal Converter _Caterpillar

Wiring the 9X-9591 Electrical Converter Gp (PULSE WIDTH MODULATED){1421, 1901, 7490} Caterpillar

Usage: 3512B 1PW 3516B 2FW 3508B 3DM 3508B 3DW 3412C 4BZ 3512B 4TN 3508B 5KW 3508B 5PS 3512B 6GW 3508B 6PN 3406E 8AZ 3516B 9AN 3412C 9EP 3406E 9WR 3412C BCW C-10 BCX C-12 BDL 3126B BEJ C-15 BEM C-16 BFM 3456 C1G 3456 C3G C9 C9A 3456 CAH 3516B CBN C18 CKH 3512B CMC 3508B CNB 3126B DCS C18 G4C C9 JSC 3508C LLC 3508B S2D 3508B S2E 3512B S2J 3512B S2K 3512B S2L 3512B S2N 3516B S2X C18 STM C32 SXC

Engine: 3512B (S/N: 1PW1-UP; CMC1-UP; S2J1-UP; S2K1-UP; S2L1-UP; S2N1-UP; 4TN1-UP; 6GW1-UP) 3126B (S/N: BEJ1-UP; DCS1-UP) 3412 (S/N: 4BZ1-UP) 3412C (S/N: 9EP1-UP; BCW1-UP) 3508B (S/N: CNB1-UP; S2D1-UP; S2E1-UP; 3DM1-UP; 6PN1-UP; 5PS1-UP; 3DW1-UP; 5KW1-UP) 3508C (S/N: LLC1-UP) 3516B (S/N: CBN1-UP; 9AN1-UP; 2FW1-UP; S2X1-UP) C-10 (S/N: BCX1-UP) C-12 (S/N: BDL1-UP) Generator Set: 3406E (S/N: 8AZ1-UP) 3456 (S/N: C1G1-UP; C3G1-UP; CAH1-UP) C18 (S/N: G4C1-UP; STM1-UP) C32 (S/N: SXC1-UP) C9 (S/N: C9A1-UP) Industrial Engine: C-15 (S/N: BEM1-UP) C-16 (S/N: BFM1-UP) C9 (S/N: JSC1-UP) Marine Engine: 3406E (S/N: 9WR1-UP) C18 (S/N: CKH1-UP)

Introduction Do not perform any procedure in this Special Instruction until you read this information and you understand this information. The 9X-9591 Electrical Converter Gp (PULSE WIDTH MODULATED) is used i n some marine, industrial, and generator set applications. The converter is used in order to provide local speed control and remote speed control. The converter provides the inputs for desired speed and droop signal to the engine's Electronic Control Module (ECM).

Illustration 1

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(S) Terminal - desired speed output. Controlled b y an external 1K or 2K potentiometer (D) Terminal - droop output. C ontrolled by an internal 2K potentiometer

The output for the desired speed signal (S terminal) i s a PWM (pulse width modulation) signal that is approximately between 5 percent and 95 percent duty cycle a t a constant frequency. This speed signal varies with the position of an external potentiometer that is connected to terminals 1, 2, and 3. The ECM calculates the desired engine RPM from the signal from the S terminal when the duty cycle is between 5 percent and 95 percent. If the ECM reads the S terminal signal as invalid, the ECM will take action based upon application and may set engine speed low i dle. The output for droop (D terminal) is a PWM signal between 5 percent and 95 percent duty cycle at a constant frequency. The output of the droop signal varies with the position of an internal potentiometer. The ECM calculates the desired engine RPM from the D terminal signal. If the ECM reads the D terminal signal as invalid, the engine will run in isochronous mode. Note: The droop PWM signal may not be used in a ll applications.

Incorrect Wiring If the external potentiometer is not wired c orrectly the inability to run the engine a t the customer specified engine speeds may occur. For example by turning the potentiometer clockwise the engine speed may decrease. Refer t o Illustration 2.

Illustration 2

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Incorrect wiring

Correct Wiring 1. Verify that the external potentiometer is wired correctly to terminals 1, 2, and 3 of the PWM converter. Refer to Illustration 3 for the correct wiring of the external potentiometer to the PWM converter.

Illustration 3

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Correct wiring

a. By turning the wiper clockwise, the resulting voltage will increase. The resistance between terminal 2 and terminal 3 will go down. This will indicate that the connection is between the terminal signal and the high side of the potentiometer. The system response will be an increase in engine RPM.  b. By turning the wiper counterclockwise, the resulting voltage will decrease. The resistance  between terminal 2 and terminal 1 will go up. This will indicate the connection is between the terminal signal and the low side of the potentiometer. The system response will be a decrease in engine RPM. 2. Conduct any additional functional testing and troubleshooting referring to the engine's Troubleshooting manual for further information in r egards to PWM converter.