The Dee-3 Microcomputer is a generator-set controller. It is used on generator sets from Dee-3, including the Microcomputer Controller.
| Symptom | Cause | Remedy |
|---|---|---|
| Battery voltage must show at connector Pl-12 socket in order for controller to function | Check voltage from Pl-12 socket to ground (Figure 3-8). | |
| Blown Fuse | Defective gauges, Connector P2, socket 1 to ground; Overvoltage, Connector P2, socket 2 to ground; Crank, Connector Pl, socket 1 to ground; Safeguard Breaker, Connector Pl, socket 3 to ground; Generator Field Flash, Connector Pl, socket 4 to ground; Engine Run, Connector Pl, socket 7 to ground | |
| Engine will not crank with Master Switch in RUN position (no power to controller circuit board) | Battery weak or dead, Reversed or loose battery connections, Faulty Pl connector or DC wire harness | Recharge or replace battery. Verify proper operation of battery charger. Check for proper battery connection (negative - ground). Clean and tighten battery connections. |
| Generator set will not start or stops running due to a fault shutdown (fault lamp lit) | Engine Coolant Temperature above 225°F (107°C). Cooling System Malfunction. Engine oil pressure between 5.5-10.5 psi (38-72 kPa) on diesel-powered models; 11.5-18.5 psi (79-126 kPa) on gasoline-powered models. Governed frequency in excess of 70 Hz (all models). More than 45 seconds of continuous cranking. More than 75 seconds of cyclic cranking. Locked rotor. Overcrank Lamp Flashes: Speed sensor signal absent longer than one second. | Consult the Engine Service Manual for detailed information on correcting engine related faults. To reset the set after a fault shutdown, see Section 2. Dee-3 Controller - “Resetting.” |
| High engine coolant temperature | Check coolant level. Check ignition timing. Check for cooling restrictions and radiator cooling air. | |
| K4 (emergency stop) relay: defective | Engine electrics, overvoltage board, circuit board | Isolate the defective component and repair or replace. |
| No fuel | Check for fuel at pump or carburetor. Check for clogged fuel filter. Check engine fuel system. Ignition system. Check for battery voltage at ignition coil. Check ignition points. Check engine ignition system. | |
| Overspeed | Governed frequency exceeding 70 Hz will energize SDR relay and shutdown unit. Overspeed shutdown may be caused by governor malfunction/misadjustment or rapid loss of load. | |
| Unit runs for 30-60 seconds then shuts down | No AC output available to 1 CR relay coil. Safeguard breaker (if equipped) must be closed. | Check for 120 volts AC to controller terminal strip VO and V8. See generator troubleshooting (No Output). If 1CR relay does not energize, normally closed contact of relay will energize ITS thermal switch and shut down unit. |
| Unit will not crank | Reversed or poor battery, Weak or dead battery, Controller fuse blown | (Refer to Figure 3-2) Units require a negative ground. Battery cable connections must be clean and tight. Minimum voltage at battery must be 10 Volts with controller switch in TEST position. Controller fuse blown (15 Amp.) See “Fuse”, Section 2. Will not crank (No voltage to CR coil) Shutdown due to fault protection Press appropriate rest switch. Open SDR or 1TS contacts in Check for battery voltage to lead 44 on master switch. SDR relay must make good contact in socket. Will not crank (CR relay energizes) Open foil pattern on relay circuit Visually inspect; make continuity check. Poor pin connection in P6 Visually inspect pin 8, 1, 2 and 13. Make continuity check. Faulty CR relay 12-volt coil resistance is approximately 125 ohms. Measure between terminals A and B. Normally closed contacts (continuity) are l-7, 2-8, 3-9. |
Fault codes and symptom→remedy steps extracted from this controller’s service/owner documentation; verify against the official manual before servicing. Aggregated from the service documentation of generator sets built on this controller.