DDEC III/IV Single ECM Troubleshooting

Section 10.2 Engine Cranks But Will Not Start

Section 10.2
Engine Cranks But Will Not Start

The following procedures will diagnose engine cranks but will not start. ‪

Section 10.2.1
Check Engine Light

Perform the following steps to check the CEL:‪

  1. Turn ignition on while observing the Check/Stop Engine Light.
    1. If the light comes on and stays on, refer to "9.1 First Step for Diagnosing a Fault Within the DDEC System" .
    2. If the light comes on for up to five seconds, and then goes off, refer to "10.4.2 Display ECM Light Status" .
    3. If the lights are off, refer to "10.2.14 Check DDEC Fuses" .

Section 10.2.2
Fuel Check

Perform the following steps to check the fuel supply:‪

  1. Disconnect the fuel return line.
  2. Check for fuel flow while cranking the engine.
    1. If fuel flow is okay, refer to "10.2.3 White Smoke Check" .
    2. If fuel supply is not okay, refuel the vehicle. The system may need to be re-primed. Refer to the appropriate engine service manual.

Section 10.2.3
White Smoke Check

Perform the following steps to check for white smoke:‪

  1. Reconnect fuel return line.
  2. Look for white smoke coming out of the exhaust stack while cranking the engine.
    1. If white smoke is present, refer to "10.2.4 Check Timing Reference Sensor Status" .
    2. If white smoke is not present, refer to "10.2.28 Check Fuel Filters" .

Section 10.2.4
Check Timing Reference Sensor Status

Perform the following steps to check the TRS status via a r/min readout:‪

  1. Select engine speed and active codes on the DDR.
  2. Crank the engine for ten seconds while observing DDR display. A battery voltage surge while cranking with electric starters may blank or reset the DDR.
    1. If the display reads greater than or equal to 60 r/min, refer to "10.2.9 Check for Good Synchronous Reference Sensor Signal" .
    2. If the display reads less than 60 r/min or constantly reads 60 r/min, refer to "10.2.5 Check Timing Reference Sensor" .
    3. If code 41 is displayed, refer to "41.3.1 Check for Signal Open" .
    4. If code 42 is displayed, refer to "42.3.1 Resistance Check" .

Section 10.2.5
Check Timing Reference Sensor

Perform the following steps to check the TRS:‪

  1. Turn vehicle ignition OFF.
  2. Disconnect engine harness connector at the ECM.
  3. Measure resistance between sockets T1 and T2 at the engine harness connector.
    1. If the resistance measurement is greater than 136 Ω, refer to "41.3.3 Open Timing Reference Sensor Line Check" .
    2. If the resistance measurement is less than 100 Ω, refer to "41.3.2 Check for Short" .
    3. If the resistance measurement is between 100 and 136 Ω, refer to "10.2.6 Check Synchronous Reference Sensor / Timing Reference Sensor Mounting" .

Section 10.2.6
Check Synchronous Reference Sensor / Timing Reference Sensor Mounting

Perform the following steps to check the SRS/TRS mounting and the bracket:‪

  1. Inspect SRS/TRS mounting.
    1. If the sensor and mount are secure, refer to "10.2.7 Check Pulse Wheel" .
    2. If the sensor and mount are not secure, tighten the bolt or replace if necessary. Refer to "10.2.27 Verify Repairs" .

Section 10.2.7
Check Pulse Wheel

Perform the following steps to check the pulse wheel:‪

  1. Inspect DDEC® pulse wheel for loose wheel or chipped or missing teeth.
    1. If the pulse wheel is damaged, repair or replace as necessary. Refer to "10.2.27 Verify Repairs" .
    2. If the pulse wheel is not damaged, refer to "10.2.8 Check ECM Connectors" .

Section 10.2.8
Check ECM Connectors

Perform the following steps to check the ECM connectors:‪

  1. Turn vehicle ignition OFF.
  2. Disconnect all connectors at the ECM.
  3. Check terminals at all ECM connectors (both the ECM and harness side) for damaged, bent, corroded or unseated pins or sockets.
    1. If the terminals and connectors are damaged, repair them. Refer to "10.2.27 Verify Repairs" .
    2. If the terminals and connectors are not damaged, replace the ECM. Refer to "10.2.27 Verify Repairs" . (Try a test ECM first.)

Section 10.2.9
Check for Good Synchronous Reference Sensor Signal

Perform the following steps to check for a good SRS signal:‪

  1. Select engine data list on DDR.
  2. Crank engine while observing DDR display of SRS received. Battery voltage surges while cranking with electric starters may blank or reset the DDR.
    1. If the SRS RECEIVED signal is YES, refer to "10.2.11 Check for Open" .
    2. If the SRS RECEIVED signal is NO, refer to "10.2.10 Check Synchronous Reference Sensor" .

Section 10.2.10
Check Synchronous Reference Sensor

Perform the following steps to check the SRS:‪

  1. Turn vehicle ignition OFF.
  2. Disconnect engine harness connector at the ECM.
  3. Measure resistance between sockets S1 and S2 at the engine harness connector.
    1. If the resistance measurement is greater than 136 Ω, refer to "41.3.3 Open Timing Reference Sensor Line Check" .
    2. If the resistance measurement is less than 100 Ω, refer to "41.3.2 Check for Short" .
    3. If the resistance measurement is between 100 and 136 Ω, refer to "10.2.6 Check Synchronous Reference Sensor / Timing Reference Sensor Mounting" .

Section 10.2.11
Check for Open

Perform the following steps to check if the injector return wires are open: ‪

  1. Turn ignition OFF.
  2. Disconnect the 5-way injector harness connector at the ECM.
  3. Measure resistance between the injector return pin and all the power driver pins on both harness connectors.
    1. If the resistance measurement is greater than 5 Ω on any reading, an open circuit exists in one of the injector power driver or return wires. Repair the break. Refer to "10.2.27 Verify Repairs" .
    2. If the resistance measurement is less than or equal to 5 Ω on any reading, refer to "10.2.12 Short to Ground" .

Section 10.2.12
Short to Ground

Perform the following steps to check if the injector lines are shorted to the ground:‪

  1. Disconnect the 5-way injector harness connector at the ECM.
  2. Measure resistance between socket D of the 5-way power harness connector to the following sockets on the injector harness connector: A, B, C, D, E, G, H, J, K and L.
    1. If the resistance measurement is greater than or equal to 10,000 Ω or open on all readings, refer to "10.2.13 Injector Drive Pulses" .
    2. If the resistance measurement is less than 10,000 Ω on any reading, there is a short to ground on the wire where resistance was less than 10,000 Ω. Repair the short and refer to "10.2.27 Verify Repairs" .

Section 10.2.13
Injector Drive Pulses

Perform the following steps to check the injector drive pulses:‪

  1. Turn ignition OFF.
  2. Reconnect all ECM connectors. See Figure "5-Way ECM Power Harness Connector" .
  3. Remove rocker covers.
  4. Disconnect return wire #619 or #620 from one injector.
  5. Place a 6-volt test light across the previously disconnected injector return side and a good ground.
  6. Crank engine and note the test light to see if it lights (flashes).
  7. Reconnect the return wire.
  8. Repeat the above procedure with all other injectors until all have been tested or until one test fails.
    1. If all tests pass, the problem does not appear to be in the DDEC system.
    2. If all tests do not pass and the test light is flashing for one or more tests, check for proper parts (e.g. bull gear) then try a test ECM. Refer to "10.2.27 Verify Repairs" .
    3. If all tests do not pass and the test light is not flashing for one or more tests, refer to "10.2.8 Check ECM Connectors" .
    4. Click to see this graphic in a separate window

      Figure 1. 5-Way ECM Power Harness Connector

Section 10.2.14
Check DDEC Fuses

Perform the following steps to check the DDEC fuses:‪

  1. Check both ECM power fuses or circuit breakers.
    1. If both fuses are okay, refer to "10.2.15 Battery Volts Check" .
    2. If either fuse is not okay, refer to "10.2.25 Check for Blown Fuses" .

Section 10.2.15
Battery Volts Check

Perform the following steps to check for battery volts at the 5-way connector:‪

Note: A high resistance in these wires may prevent engine starting but measure correct voltage. Proper resistance based on wire length and size is listed in Table "Maximum Resistance vs Power Harness Length" .

  1. Turn ignition OFF.
  2. Disconnect the 5-way power harness connector at the ECM. See Figure "5-Way ECM Power Harness Connector" .
  3. Measure voltage from socket A (red lead) of 5-way power harness connector to a good ground.
  4. Measure voltage from socket C (red lead) of 5-way power harness connector to a good ground.
    1. If the voltage measurement is greater than 11.5 volts on all readings, refer to "10.2.18 Check Volts at Ignition Wire" .
    2. If the voltage measurement is less than 11.5 volts on any readings, refer to "10.2.16 ECM Power Line Check" .
    3. Click to see this graphic in a separate window

      Figure 2. 5-Way ECM Power Harness Connector

Section 10.2.16
ECM Power Line Check

Perform the following steps to check if the ECM power lines are open:‪

  1. Measure voltage between battery side of one ECM fuse or circuit breaker (red lead) and a good ground (black lead).
  2. Measure voltage at other ECM fuse or circuit breaker. Note that battery side does not contain #240 or #241 wires. See Figure "Power Harness Diagram" .
    1. If the voltage measurement is less than 11.5 volts on any reading, refer to "10.2.17 Check Battery" .
    2. If the voltage measurement is greater than 11.5 volts on all readings, an open circuit exists in either power wire (#240 or #241). Repair the break; refer to "10.2.27 Verify Repairs" .
    3. Click to see this graphic in a separate window

      Figure 3. Power Harness Diagram

Section 10.2.17
Check Battery

Perform the following steps to check the battery:‪

  1. Connect all connectors.
  2. Turn ignition ON.
  3. Measure voltage at battery (+) terminal (red lead) to the battery (-) terminal (black lead).
    1. If the voltage reading is less than 11.5 volts, service the discharged battery. Refer to "10.2.27 Verify Repairs" .
    2. If the voltage reading is greater than or equal to 11.5 volts, an open circuit or short to ground exists in the battery (+) line. Repair the open circuit. Refer to "10.2.27 Verify Repairs" .

Section 10.2.18
Check Volts at Ignition Wire

Perform the following steps to check for +12 or +24 volts at the ignition wire:‪

  1. Turn ignition OFF.
  2. Disconnect the vehicle harness connector at the ECM. For vehicle harness schematic, see Figure "ECM Vehicle Harness Connector" .
  3. Turn ignition ON.
  4. Measure voltage between socket B3 on the vehicle harness connector (red lead) and a good ground (black lead).
    1. If the voltage measurement is greater than or equal to 11.5 volts, refer to "10.2.19 Ground Wire Check" .
    2. If the voltage measurement is less than 11.5 volts, refer to "10.2.20 Check Ignition Fuse" .
    3. Click to see this graphic in a separate window

      Figure 4. ECM Vehicle Harness Connector

Section 10.2.19
Ground Wire Check

Perform the following steps to check for a good ground wire:‪

  1. Measure voltage between socket B3 on the vehicle harness connector (red lead) and sockets D and E of the 5-way power harness connector. For 5-way ECM power harness schematic, see Figure "5-Way ECM Power Harness Connector" .
    1. If the voltage measurement is greater than or equal to 11.5 volts, refer to "10.2.8 Check ECM Connectors" .
    2. If the voltage measurement is less than 11.5 volts, the ECM ground wire (circuit #150) is open or has a poor connection. Repair open ground wire; refer to "10.2.27 Verify Repairs" .
    3. Click to see this graphic in a separate window

      Figure 5. 5-Way ECM Power Harness Connector

Section 10.2.20
Check Ignition Fuse

Perform the following steps to check the ignition fuse:‪

  1. Turn ignition OFF.
  2. Check 5-amp ignition fuse or circuit breaker.
    1. If both the fuse and circuit breaker are okay, refer to "10.2.21 Check for Open" .
    2. If the fuse or circuit breaker are not okay, refer to "10.2.22 Check for Ground" .

Section 10.2.21
Check for Open

Perform the following steps to check if the ignition wire is open:‪

  1. Measure voltage between battery side (hot side) of the 5-amp ignition fuse (red lead) and a good ground (black lead).
    1. If the voltage measurement is less than 11.5 volts, refer to "10.2.24 Check Battery" .
    2. If the voltage measurement is greater than or equal to 11.5 volts, the ignition line (circuit #439) is open. Repair the break; refer to "10.2.27 Verify Repairs" .

Section 10.2.22
Check for Ground

Perform the following steps to check if the ignition wire is shorted to ground:‪

  1. Replace blown fuse or reset open circuit breaker.
  2. Turn ignition ON for ten seconds.
  3. Run engine for one minute.
  4. Turn ignition OFF.
  5. Check 5-amp ignition fuse or circuit breaker again.
    1. If both the fuse and circuit breaker are okay, refer to "10.2.23 Check Fuse or Circuit Breaker" .
    2. If the fuse and circuit breaker are not okay, the ignition line (circuit #439) is shorted to ground. Repair the short; refer to "10.2.27 Verify Repairs" .

Section 10.2.23
Check Fuse or Circuit Breaker

Perform the following steps to check if the ignition fuse or breaker is okay:‪

  1. Reconnect all harness connectors at the ECM.
  2. Start the engine.
  3. Run engine for one minute.
  4. Turn ignition OFF.
  5. Check 5-amp ignition fuse or circuit breaker again. For 5-way ECM power harness schematic, see Figure "5-Way ECM Power Harness Connector" .
    1. If both the fuse and circuit breaker are okay, no short is currently present. Be warned of an intermittent short that could shut down the engine or blow a fuse due to reverse voltage at the battery. Refer to "10.2.27 Verify Repairs" .
    2. If the fuse or circuit breaker are not okay, refer to "10.2.8 Check ECM Connectors" .
    3. Click to see this graphic in a separate window

      Figure 6. 5-Way ECM Power Harness Connector

Section 10.2.24
Check Battery

Perform the following steps to check the battery:‪

  1. Disconnect the battery cables at the battery.
  2. Measure voltage at the battery (+) terminal (red lead) to the battery (-) terminal (black lead).
    1. If the voltage measurement is less than 11.5 volts, service the discharged battery. Refer to "10.2.27 Verify Repairs" .
    2. If the voltage measurement is greater than or equal to 11.5 volts, an open circuit or short to ground exists in unfused ignition line. Repair the break. Refer to "10.2.27 Verify Repairs" .

Section 10.2.25
Check for Blown Fuses

Perform the following steps to check for blown fuses:‪

  1. Turn ignition OFF.
  2. Disconnect the 5-way power harness connector at the ECM.
  3. Replace blown fuse(s) or reset the circuit breaker(s).
  4. Wait ten seconds.
  5. Check whether fuse(s) or circuit breaker(s) have blown or opened up again.
    1. If the fuse and circuit breaker are okay, refer to "10.2.23 Check Fuse or Circuit Breaker" .
    2. If the fuse or circuit breaker are not okay, refer to "10.2.26 Check for Short to Ground" .

Section 10.2.26
Check for Short to Ground

Perform the following steps to check for a short to ground:‪

  1. Disconnect the batteries.
  2. Measure resistance between #240 and a good ground (black lead).
  3. Measure resistance between #241 and a good ground (black lead).
    1. If the resistance measurement is greater than or equal to 10,000 Ω on all readings, refer to "10.2.8 Check ECM Connectors" .
    2. If the resistance measurement is less than 10,000 Ω on any readings, a short to ground exists. Repair the short. Refer to "10.2.27 Verify Repairs" .

Section 10.2.27
Verify Repairs

Perform the following steps to verify repairs:‪

  1. Turn ignition OFF.
  2. Reconnect all connectors.
  3. Turn ignition ON.
  4. Clear codes.
  5. Start and run the engine for one minute.
  6. Stop the engine.
  7. Read inactive codes.
    1. If the engine starts and no codes are displayed, troubleshooting is complete.
    2. If the engine does not start, refer to "10.2.1 Check Engine Light" .
    3. If the engine starts and codes display, refer to "9.1 First Step for Diagnosing a Fault Within the DDEC System" .

Section 10.2.28
Check Fuel Filters

Perform the following steps to check fuel filters:‪

  1. Turn ignition OFF.
  2. Check primary and secondary fuel filters to be sure they are not clogged and they are filled with clean fuel.
    1. If the fuel filters are clean, refer to "10.2.4 Check Timing Reference Sensor Status" .
    2. If the fuel filters are not clean, replace the filters. Prime the system if required. Refer to "10.2.27 Verify Repairs" .

Note: For information concerning Fuel Filters, refer to section 29.4.11 in the appropriate service manual. For information concerning Fuel Filter Replacement, refer to section 18 in the appropriate service manual.


DDEC III/IV Single ECM Troubleshooting Guide - 6SE497
Generated on 10-13-2008

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