Table 4-2. Unit Troubleshooting-continued -706880237

TM 5-4210-233-14&P-1

Table 4-2. Unit Troubleshooting - Continued

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

ELECTRICAL SYSTEM - JACOBS ENGINE BRAKE - Continued

JACOBS ENGINE BRAKE WORKS ONLY IN ONE SWITCH POSITION

(Refer to Electrical Wiring Diagrams, Appendix H, Sheet 14 of 16.)

Step 1. Check switch.

Replace switch (see para 4-9.4).

Step 2. Check wiring for continuity.

Replace wiring (see para 4-9.4).

Step 3. Check solenoid valve at engine brake for proper operation.

Replace solenoid valve (see para 4-9.4).

JACOBS BRAKE WORKS WHILE VEHICLE IS SHIFTED TO "PUMP" MODE

(Refer to Electrical Wiring Diagrams, Appendix H, Sheet 14 of 16.)

Step 1. Check wire 1657 from pump shift switch to auto disengage relay for continuity.

Replace wire (see para 4-9.4).

Step 2. Check auto disengage relay for proper operation.

Replace relay (see para 4-9.4).

JACOBS BRAKE WORKS WHEN THROTTLE IS DEPRESSED

(Refer to Electrical Wiring Diagrams, Appendix H, Sheet 14 of 16.)

Step 1. Check wire D508 from DDEC to throttle control relay for continuity.

Replace wire (see para 4-9.4).

Step 2. Check throttle control relay for proper operation.

Replace relay (see para 4-9.4).

Step 3. Check DDEC for ground on pin A1 of connector 1 when throttle is released.

Replace ECM. Notify Direct Support.

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