Table 4-2. Unit Troubleshooting-continued -706880238

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

BRAKE LIGHTS DO NOT ILLUMINATE WHEN JACOBS BRAKE IS ENGAGED

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

Step 1. Confirm that Jacobs brake is functioning properly.

Refer to Jacobs brake troubleshooting procedure.

Step 2. Check Jacobs brake light relay for proper operation.

Replace relay (see para 4-9.4).

Step 3. Check wiring for continuity.

Replace wire (see para 4-9.4).

Step 4. Refer to brake light troubleshooting procedure.

ELECTRICAL SYSTEM - HI-IDLE CIRCUITS

HIGH IDLE SWITCH IN CAB WILL NOT ENGAGE HIGH IDLE

(Refer to Electrical Wiring Diagrams, Appendix H, Sheet 3 of 16.)

Step 1. Check that parking brake is engaged.

Engage parking brake.

Step 2. Check that transmission selector is in N (neutral).

Place transmission selector in N (neutral).

Step 3. Check HIGH IDLE switch.

Replace switch (see para 4-9.4).

Step 4. Check for +12V signal at neutral safe relay (CRY030) coil.

Replace CRY030 (see para 4-9.4).

Step 5. Check CRY032 for 12V signal at coil.

Replace park brake PSI switch (see para 4-9.4).

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