ENGINE AR-PRIMARY 4484798 - Caterpillar

Review the procedures before removing and installing the Engine ECM connectors. Do not force the connectors onto the ECM. Do not force the lever lock. Failure to follow the instructions in UENR2328 can cause damage to the ECM pins, may create various faults, and may require ECM replacement.
ECM Memory Test
Table 1
Diagnostic Codes
Code Description Conditions Notes
628-2 ECU Flash ROM Error Key switch is On
Flash ROM error occurs three times or more.
Warning Level 3
Engine stops
651-8 TWV1 driving circuit error (Cylinder #01) Battery voltage is normal
During Injection
ECM CPU is normal Wiring Harness short / open circuit
Engine derates 75%
EGR Stop
652-8 TWV2 driving circuit (Cylinder #02) Battery voltage is normal
During Injection
ECM CPU is normal Wiring Harness short / open circuit
Engine derated 75%
EGR Stop
653-8 TWV3 driving circuit (Cylinder #03) Battery voltage is normal
During Injection
ECM CPU is normal Wiring Harness short / open circuit
Engine derated 75%
EGR Stop
654–8 TWV4 driving circuit (Cylinder #04) Battery voltage is normal
During Injection
ECM CPU is normal Wiring Harness short / open circuit
Engine derated 75%
EGR Stop
1077-2 ECU CPU Error (Main IC) Key switch is On
Battery voltage is 10 V or greater.
Starter switch is Off
CPU abnormality counter-occurs five times or more
Warning Level 3
Engine stops
523527-2 ECU CPU Error (Monitoring IC)
Key switch is On
Battery voltage is 10 V or more
Starter switch signal (P1/J1 Terminal 12) is not activated
Abnormality continuous for 2 seconds or more after the ECU is turned On.
RUN pulse abnormality.
Above conditions occur continuously for .7 seconds or more.
Warning Level 3
Engine stops.
Table 2
Troubleshooting Test Steps Values Results
651-3, 652-3, 653-3, 654-3
1. Measure Resistance
A. Measure the resistance between the engine ECM terminals at the engine ecm harness connector.
ECM
Result: 1.5 Ω or lower
Proceed to Test Step 2.
Result: Not 1.5 Ω or lower
Proceed to Test Step 4.
2. Clear Codes
A. Reconnect engine ecm connector to ECM. Start machine and clear diagnostic codes.
ECM
Result: Code does not return.
STOP
Result: The code returns.
Proceed to Test Step 3.
3. Check the Connectors
A. Check the connectors and wiring harness for poor contact or damage.
Engine Harness
Result: No visible damage to harness.
Proceed to Test Step 4.
Result: There is damage to the harness.
Repair: Replace the harness.
4. Measure the Resistance Between the Fuel Injector Terminals
A. Unplug the fuel injector harness connector and measure the resistance between terminals 1 and 2.
Fuel Injector
Result: 0.4 to 0.7 Ω.
STOP
Result: Not 0.4 to 0.7 Ω.
Repair: Replace the faulty fuel injector.
Contact your Technical Communicator for more assistance.
Table 3
Troubleshooting Test Steps Values Results
1. Keyswitch off. Keyswitch On. Clear the Codes. Try to restart the engine.
Codes
Results: If the code is still active and the engine does not start, proceed to Test Step 2.
2. Check that there is an electromagnetic interference (EMI).
Electromagnetic Interference
Results: There is no EMI in the area.
Proceed to Test Step 3.
Result: There is EMI in the area.
Move the machine from that area and try to restart the engine.
3. Swap Engine ECM from Another Machine
ECM
Results: If diagnostic codes are still active, install a replacement ECM from another machine. If this resolves, contact your local Technical Communicator for DSN support.