Relay Inspection and Replacement on Certain Gensets{4460, 4493} Caterpillar

Generator Set:

C15 GEN SET (S/N: C5E2774-2864; C5H1451-1580)

C18 GEN SET (S/N: N1D174-275; EKW1023-1029)

C9 GEN SET (S/N: C9E2024-2153)

Introduction

Do not perform any procedure in this Special Instruction until you read this information and you understand this information.

The above listed C9, C15, and C18 serial number generator sets may have been built with 12V rated relay which powers the Electronic Control Module (ECM). The applications that the12V rated relays are installed in require a 24V rated relay. The undersized relay will function normally but will eventually fail. Failure of the relay will cause the unit to shut down and fail to restart. The relay should be inspected for the affected generator sets. If the relay is rated for 12V, the relay should be removed and replaced with the 24V 206-9427 Relay .

Safety Section

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Do not disconnect equipment unless power has been disconnected or the area is known to be non-hazardous

Relay Inspection and Replacement Instructions

Locate the Connection Box

Illustration 1	g02771278
(1) 166-0845 Connection Box

The connection box (1) is located on the backside of the control box. Illustration 1 shows the general location of the connection box.

Remove Connection Box Face Plate

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Illustration 2	g02776777
(2) Four Phillips head bolts (3) Connection box face plate

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Illustration 3	g02776779
(4) 24V 206-9427 Relay (5) Ground wire

1. The connection box face plate (3) is secured by four Phillips head bolts (2) shown in Illustration 2. Remove the four bolts with a standard Phillips head screwdriver.

2. Gently set the face plate down directly below the connection box since the grounding wire (5) is still connected to the face plate and the connection box. Refer to Illustration 3

Inspect the Existing Relay

Illustration 4	g02776781
(6 ) Relay rating marking location

Illustration 5	g02776784
(7) 12V relay marking

Illustration 6	g02776787
(8) 24V relay marking

Inspect the existing relay to determine if the rating is for a 12V or 24V relay. Look for a "12VDC" or a "24VDC" marking. The markings (6) are found on the right side of the relay as installed in the connection box. Refer to Illustration 4 for an example of an installed relay with the markings. Illustration 5 shows the "12VDC" marking (7) and Illustration 6 shows the"24VDC" marking (8) on the relays.

Replacing the 12V Relay

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Illustration 7	g02776790
(9) Wires to be disconnected (10) Phillips head bolt

1. If the marking on the installed relay is "24VDC", the relay is correct and should be left as is. The connection box face plate should be replaced, and the four Phillips head bolts reinstalled and hand tightened.

2. If the marking on the installed relay is "12VDC", the relay is incorrect and must be removed. Remove the relay by unscrewing the Phillips head bolt (10) on the right side of the relay.

3. Once the bolt is removed, disconnect the wires (9) that are plugged into the terminals on the left side of the relay. Disconnect the wires, by grabbing the plastic connector at the end of the wire and pull directly away from the relay. The connector will not release from the relay if the harness is pulled only by the wire. Refer to Illustration 7 for the location of the bolt and wires.

Reconnecting the 24V 206-9427 Relay

Illustration 8	g02776793
Top view of relay All terminal callouts are from the terminal end of the relay (11) Left side terminal (12) Top terminal (13) Metal mounting tab (14) Right side terminal (15) Wire labeled "2" or "45" (16) Wire labeled "B+" (17) Wire labeled "10"

1. After removing the 12V relay, install the 24V relay into the connection box.

2. Connect the 24V relay to the previously removed wires. Illustration 8 shows the proper wiring of the 24V relay. The relay in Illustration 8 should be installed in the connection box with the metal mounting tab (13) on the bottom, pointing toward the right. In this orientation, only three of the terminals can be seen. The left side terminal (11) in this orientation should be connected to the wire labeled "10" (17). The top terminal (12) in this orientation should be connected to the wire labeled "B+" (16). The right side terminal (14) in this orientation should be connected to the wire labeled either "2" or "45" (15) .

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Illustration 9	g02776795
Side view of relay (18) Wire labeled "A+" (19) Bottom terminal

3. The wire labeled "A+" (18) should be attached to the bottom terminal on the relay (19). Refer to Illustration 9. This connection is shown in with the relay in an alternate orientation. There will be a central terminal that will not be connected to any wires.

Installing the 24V Relay into the Connection Box

After wiring the 24V relay secure the relay inside the connection box. Using the Phillips head bolt removed previously from the 12V relay, reinsert the bolt through the metal tab on the 24V relay. Using a standard Phillips head screwdriver, hand tightened the bolt in the same location inside the connection box. With the same screwdriver replace the connection box front panel by hand tightening the four Phillips head bolts from the previously removed panel.