Figure 2-48. Removal of ECU panel assembly.

TM 5-6675-250-34

Table 2-1. TroubleshootingContinued

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

c. Disconnect two electrical connectors (2A1P5 and 2A1P6) by unfastening two screws at each connector.

d. Inspect printed circuit board for visual evidence of cracked circuits, corrosion, burns, or other

evidence of defects.

Replace a bad printed circuit board.

CAUTION

To avoid damaging, the electrical connectors, alternate tightening each of thetwoscrews during reassembly.

(1). Install a good printed circuit board, but do not tighten mounting screws. Connect the two

electrical connectors and secure by tightening two screws. Fasten ten screws that secure printed

circuit board to mounting brackets.

(2). Install electronic control panel assembly incaseand secure with eight captive screws.

Step 3. Check for defective MODE SELECT (2A2S3) switch or BIAS control (2A2R4) on ECU.

a. Loosen the eight captive screws and lift the electronic control panel assembly from the case (fig. 2-48).

CAUTION

TS 006287

Figure 2-48. Removal of ECU panel assembly.

b. Unfasten ten screws securing the printed circuit board to mounting brackets and loosen the board

to obtain access to electrical connectors.

CAUTION

To avoid damage to the electrical connectors, alternately back-off each of the two attaching screws when removing the

connectors.

c. Disconnect two electrical connectors (2A2J5 and 2A2J6) by unfastening two screws at each connector.

and output

d. Use an ohmmeter and check continuity of MODE SELECT switch (2A2S3) between input pins (A, B, and C)

and output pins (1 thru 6).

e. Use an ohmmeter and check continuity between pins 1, 2, and 3 of BIAS control (2A2R4) variable resistor.

If continuity is not present, replace a bad switch.

(1). Place MODE SELECT switch (fig. 2-49) to GC position.

(2). Place TEST SELECT switch to source voltage position.

2-38