The ECM controls the following:
| • | The fuel system pressure |
| • | The fuel injection timing |
The ECM constantly monitors the information from various sensors. The ECM controls the systems that affect engine performance. The ECM performs the diagnostic function of the system. The ECM can recognize operational conditions, alert the driver through the malfunction indicator lamp (MIL), and store diagnostic trouble codes (DTCs). DTCs identify the faulty areas to aid the technician in making repairs.
The main relay supplies electric power.
Diagnostic Aids
Inspect for the following conditions:
| • | Poor connection at the main relay |
| Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection. |
| • | Damaged harness |
| Inspect the wiring harness for damage, shorts to ground, shorts to battery, and open circuits. If the harness appears to be OK, observe the power supply or data list display on the scan tool while moving connectors and wiring harnesses related to the main relay. A change in the scan tool display will indicate the location of the fault. |
Step | Action | Value | Yes | No |
|---|---|---|---|---|
1 | Is the engine oil within the specified viscosity? | -- | Go to Step 2 | Go to Step 10 |
2 | Is the fuel within the recommended specification? | 30-44 API Gravity | Go to Step 3 | Go to Step 11 |
3 | Bleed the air from the fuel lines. Did you complete the action? | -- | Go to Step 4 | Go to Step 12 |
4 | Inspect the engine cylinder compression. Does the compression measure more than the specified values for each cylinder? | 2157 kPa (313 psi) | Go to Step 5 | Go to Step 13 |
5 | Do the glow plugs operate properly? | -- | Go to Step 6 | Go to Step 14 |
6 | Does the exhaust brake switch turn OFF? | -- | Go to Step 7 | Go to Step 15 |
7 | Inspect the injection timing. Is the CKP sensor output normal? | -- | Go to Step 8 | |
8 | Is the voltage at the TWV within the specified range? | 100-120 V | Go to Step 9 | |
9 | Perform cylinder balance test. Do the flow dampers operate normally? | -- | Go to Step 16 | Go to Step 17 |
10 | Replace the engine oil. Is the action complete? | -- | Go to Step 18 | -- |
11 | Replace the fuel with the recommended specification. Is the action complete? | 30-44 API Gravity | Go to Step 18 | -- |
12 | Bleed the air from fuel line. Did you complete the action? | -- | Go to Step 18 | -- |
13 | Repair/replace the piston ring, the valve stem seal etc. Did you complete the action? | -- | Go to Step 18 | -- |
14 | Repair/replace the glow plug and/or the preheating system. Did you complete the action? | -- | Go to Step 18 | -- |
15 | Repair/replace the exhaust brake switch. Did you complete the action? | -- | Go to Step 18 | -- |
16 | Replace the injector assembly. Did you complete the replacement? | -- | Go to Step 18 | -- |
17 | Replace the flow damper. Did you complete the replacement? | -- | Go to Step 18 | -- |
18 | Does the engine start and run? | -- | System OK | Go to Step 1 |
