Usage:
AP-800 ( 1BF ),
AP-1200 ( 2JD ) Asphalt Pavers;
RR-250 ( 6ED ) Road Reclaimers;
SS-250 ( 6DD ) Soil Stabilizers
- SUPPLEMENT: 03/05/90
SERVICE MAGAZINE; JANUARY 8, 1990; PAGE 14; "Test Box For Electrical Displacement Control," for use on AP-800 (1BF), AP-1200 (2JD) Asphalt Pavers; RR-250 (6ED) Road Reclaimers; SS-250 (6DD) Soil Stabilizers. In "How To Use The Test Box," disregard Steps 1 and 4. The correct steps follow.
1. Use the test box with a 12 volt power supply only. Make a battery center tap connection when using the test box on RR-250 Road Reclaimers or SS-250 Soil Stabilizers. Ensure correct polarity when connecting large battery clips (5) to the battery.
4. Slowly turn potentiometer (1) toward the minimum resistance position (0 ohms) until the machine starts to move. (To reverse the direction of travel, change the position of the toggle switch on the test box.)
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Reference: Service Magazine; December 18, 1989; Page 12; "Procedure For Testing Electrical Displacement Control On Hydraulic System Ground Drive Pump".
Use the parts list and wiring diagram to construct a tool (test box) for checking the Electrical Displacement Control (EDC) on the hydraulic system ground drive pump and for moving the machine in case of an electrical system failure other than the EDC.
For asphalt paving machines only, if an electrical failure causes the brakes to be engaged, use a jumper wire to supply electrical power directly to the brake solenoid. If the brake solenoid has failed, use a portable hydraulic power supply to release the brakes when the machine is to be moved.
One small box [approximately 102 by 102 by 76 mm (4.0 by 4.0 by 3.0")] is required for mounting the components. Use 16 ga. wire for all connections except the battery connections where 14 ga. wire should be used. The wires that connect the test box to the battery and the EDC should be at least 1200 mm (4.0 ft) long. The wires with the mini-clips can be attached to the pins in the EDC connector.
Mark the 0 to 250 ohm potentiometer (1) to show the minimum and maximum resistance positions (0 ohms and 250 ohms respectively). The potentiometer should be at the maximum resistance (250 ohms) when the test box is connected to the machine.
Wiring diagram for constructing EDC Test Box and checking the EDC.
How To Use Test Box
NOTE: Before making the following checks, ensure that the machine is on flat ground with adequate room for movement forward and reverse. With the brake off, manually move the pump control valve at the EDC (see the service manual). If the machine moves, the problem is electrical. Proceed with the following checks. If the machine does not move, the problem is in the hydraulic system and further electrical checks are not necessary.
1. Ensure proper polarity when connecting large battery clips (5) to the battery.
2. Turn the potentiometer (1) to the maximum resistance position (250 ohms).
3. Connect mini-clips (6) to the EDC wiring harness.
4. Slowly turn potentiometer (1) toward the minimum resistance position (0 ohms) until the machine starts to move. (To reverse the direction of travel, reverse mini-clips (6) in the EDC wiring harness.
5. If the machine does not move and/or increase in speed as potentiometer (1) is turned toward the minimum resistance position (0 ohms), replace the EDC.
6. If the machine moves and increases speed, as potentiometer (1) is turned toward the minimum resistance position, the EDC is working correctly. Check for an electrical problem other than the EDC.