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

Electric Power Generation:

3412 (S/N: 4BZ1-UP)

Engine:

3126B (S/N: BEJ1-UP; DCS1-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)

3512B (S/N: CMC1-UP; S2J1-UP; S2K1-UP; S2L1-UP; S2N1-UP; 4TN1-UP; 1PW1-UP; 6GW1-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)

Petroleum Engine:

3508C (S/N: LLC1-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 in 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 Electronic Control Module (ECM).

Illustration 1	g01409622
(S) Terminal - desired speed output. Controlled by an external 1K or 2K potentiometer (D) Terminal - droop output. Controlled by an internal 2K potentiometer

The output for the desired speed signal (S terminal) is a PWM (pulse width modulation) signal that is approximately between 5 percent and 95 percent duty cycle at 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 set engine speed low idle based upon application.

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 all applications.

Incorrect Wiring

If the external potentiometer is not wired correctly the inability to run the engine at the customer specified engine speeds may occur.

For example by turning the potentiometer clockwise the engine speed may decrease. Refer to Illustration 2

Illustration 2	g03852340
Incorrect wiring

Correct Wiring

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Illustration 3	g03852319
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.

   1. 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.

   2. 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 Troubleshooting manual for further information in regards to PWM converter.