Instructions For Correcting Speed Surge In 3406C PEEC III Truck Engines{1408} Caterpillar

Truck Engine:

3406C (S/N: 4CK1)

Introduction

This instruction addresses the problem of a speed burp (power loss) in the 3406C PEEC III Truck Engines. This speed burp is typically followed by a speed surge (power recovery). This occurs most often during normal driving at varied vehicle speeds. The speed burp with a speed surge is eliminated with the relocation of the engine speed sensor from the fuel injection pump to the flywheel housing.

Speed surge occurs due to wear in the gears in the front gear group. This wear creates excessive clearances between the gears. The fuel pump is driven by the front gear group. There is an engine speed sensor that determines engine speed from the fuel pump camshaft. Because of the excessive clearances in the gears, the engine speed sensor does not sense the most accurate engine speed. Excessive clearances may cause the governor to react erratically. This will cause the governor to undershoot and to overshoot in the actual fuel rack position. The overall effect is a speed burp and a speed surge that is felt by the driver.

The required replacement parts are listed below. These components are designed to work with a speed signal from the flywheel.

This problem is most noticeable with the following horsepower ratings. Any horsepower ratings that are not listed must use one of the available personality modules that is closest to the necessary horsepower rating.

Required Parts

• 165-1594 Harness Assembly

• 165-1595 Harness Assembly

• 115-8109 Wire Splice

• 4P-5820 Pickup Assembly

• 3N-2704 Mounting Plate

Note: The 3N-2704 Mounting Plate can be used to install the speed buffer if a suitable mounting location cannot be found.

Installation Procedure

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Illustration 1	g00600404

1. Install speed buffer (1) on the 165-1594 Harness Assembly in a convenient location. The speed buffer is used to maintain the signal strength from the 4P-5820 Pickup Assembly in the flywheel housing to the ECM. The 3N-2704 Mounting Plate can be used if a suitable mounting location cannot be found.

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Illustration 2	g00600543

2. Remove plug (2) from the right hand side of the flywheel housing.

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Illustration 3	g00600554

3. Install 4P-5820 Pickup Assembly (3) in the flywheel housing.

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Illustration 4	g00600612

4. Install two pin connector (4) from the 165-1594 Harness Assembly to the 4P-5820 Pickup Assembly (3) .

5. Install the wire tie-wraps in order to secure the wiring harnesses.

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Illustration 5	g00600636

6. Remove the P4 connector (5) from the ECM.

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Illustration 6	g00601086

7. Use the following procedure to install the wiring for the electronic control module (ECM):

   1. Remove the green wire "6711" (Z) from pin "28". Wrap electrical tape around the end of this wire because the wire will not be used.

   2. Remove the yellow wire "6704" (W) from pin "18".
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   Illustration 7	g00600703
   New Wiring Schematic At The ECM

   3. Install the yellow wire "6704" in pin "28". See the new wiring schematic.
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   Illustration 8	g00600780

   4. Connect 165-1595 Harness Assembly (6) to the 165-1594 Harness Assembly .

   5. Install white wire (7) from the 165-1595 Harness Assembly in pin "18". See the new wiring schematic.

   6. Remove the green wire "6121" (Y) from pin "1".

   7. Install the red wire from 165-1595 Harness Assembly to pin "1". See the new wiring schematic.

   8. Install the green wire "6121" in the red splice of the 165-1595 Harness Assembly . See the new wiring schematic.

   9. Remove the black wire "6202" (X) from pin "21".

   10. Install the black wire from 165-1595 Harness Assembly to pin "21". See the new wiring schematic.

   11. Install the black wire "6202" in the black splice of the 165-1595 Harness Assembly . See the new wiring schematic.

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Illustration 9	g00600853

8. Install P4 connector (5) to the ECM.

9. Remove cover (8) from the ECM.

10. Remove the personality module from the ECM.

11. Install a new personality module. See Table 1.

12. Install cover (8) .