Article 1002 - Inoperative Accessories Due to Failed Relay Assembly

TSB #60 - February 25, 1967
(1966½ and Early 1967 "W" Series Highway Tractor)


Inoperative accessories (such as temperature warning gauges, air pressure buzzer, heater and air conditioner) on "W series highway tractors, particularly those equipped with air conditioning, may be due to failure of the accessory relay. A new heavy duty relay (C7TZ-13A435-A) and revised wiring to provide increased current load capacity became effective in production approximately December 1, 1966.

To correct the above problem on a customer complaint basis on units built prior to December 1, 1966, it is recommended that the rework of existing circuit be performed as outlined below:

Vehicles with Standard Fuse Panel
    1. Disconnect the battery ground cable.
    2. Remove the hold down screws in the console to allow the console door to hinge back, and remove the radio or cover plate as shown in Illus. S1179.
    3. Disconnect the multiple connector from the accessory relay assembly — Illus. S1179.
    4. Cut the three wires at the connector and discard the connector. Cut off the two larger wires at their entry into the main body of the taped harness. (Illus. S1179).
    5. Strip 3/8" of insulation from cut end of the smaller black wire (#16 gauge wire circuit #71, ignition switch to coil of relay) and securely crimp one Faston Receptacle (Part No. B9A-14294-L) to the stripped end of this wire. See Illus. S1180.
    6. Remove and discard the accessory relay.
    7. Procure a new relay, Part No. C7TZ-13A435-A.
    8. Elongate one mounting hole in the relay assembly bracket as shown in Illus. S1180.
    9. Mount the new relay using the existing holes and attaching bolts.
    10. Connect the female arkless terminal, previously secured to circuit #71 in Step #5, to the center male arkless terminal of the new relay. Wrap the exposed metal of this connection with plastic electricians tape. See Illus. S1180.
    NOTE: Before cutting the wires as directed in the following Steps #11 and #12, check for continuity between the terminations noted and the two larger wires cut previously from the relay. This will guarantee that the proper wires will be cut.
    11. Disconnect circuit #71A (Black wire with white insulator) from the spade terminal located on the under side of the fuse panel as shown in Illus. SI 179. Cut this wire off at its entry into the main body of the taped harness.
    12. Remove circuit #21 (Yellow wire with black insulated eyelet terminal) from the terminal stud shown in Illus. Si 179 and cut off at its entry into the harness.
    NOTE: Do not remove circuit #38 located on this same stud. Retain the existing hold down nut.
    13. Procure a jumper wire, Part No. C7TZ-14A318-A, and connect the two female arkless terminals which are located at one end of the new jumper wire assembly, to the two remaining male arkless terminals on the relay. Illus. SI180.
    NOTE: These connections can be made to either of the two outside terminals for proper function.
    14. Route the jumper wire assembly along the existing wiring and connect the eyelet terminal (circuit #21, yellow wire of jumper) to the terminal stud shown in Illus. S1179.
    15. Connect the remaining female arkless terminal (circuit #71A black wire of jumper) to the male arkless terminal on the fuse panel shown in Illus. Si 179.
    16. Carefully close the fuse panel and install the cover plate or radio, install the retaining screws and reconnect the battery.

Vehicles with Circuit Breaker Panel (Production Option)
    A. Perform Steps #1 through #10 as described for vehicles with fuse panels. NOTE: Check for continuity between the following terminations and the two wires cut from the relay to guarantee the proper wires will be cut or disconnected in Steps "B", "C", "D", and "E".
    B. Disconnect the two-wire eyelet terminal connecting circuits #71A (Black wire) and #232A (Brown wire) to the circuit breaker mounted in the panel door. See Illus. S1181.
    C. Disconnect the eyelet terminal connecting the other end of circuit #232A (Brown wire) from the circuit breaker. See Illus. S1181.
    D. Disconnect the eyelet terminal for circuit #21 (yellow wire) from the lower stud on the headlamp circuit breaker mounted on the wall. See Illus. S1181.
    NOTE: Do not remove circuits #38 and 38-A from this same stud. Retain the existing hold down nut and lock washer.
    E. Cut off the two loose wires disconnected in Steps "B", "C", and "D" at their entry into the taped portion of the harness.
    F. Procure a jumper wire, Part No. C7TZ-14A318-B, and connect the two female arkless terminals which are located at one end of the jumper wire assembly to the two remaining male arkless terminals on the relay. Illus. S1180.
    NOTE: These connections can be made to either of the two outside terminals for proper function.
    G. Route the body of the jumper assembly along the existing wiring and connect the eyelet terminal for circuit #21 (yellow wire of jumper) to the lower terminal stud of the head lamp circuit breaker shown in Illus. S1181 using nut and washer removed in Step "D".
    H. Connect the two eyelet terminals with 3" leads (Circuit #71, black wire and Circuit #232, brown wire) to the circuit breaker stud shown in Illus. S1181.
    I. Connect the remaining eyelet terminal (Circuit #232, brown wire of jumper) to the circuit breaker shown in Illus. S1181.
    NOTE: There should also be another existing eyelet terminal attached with Circuit #232 on the circuit breaker.
    J. Carefully close the circuit breaker panel and install the cover plate or radio, install the retaining screws and reconnect the battery.

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Illus. S1179
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Illus. S1180
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Illus. S1181




WARRANTY STATUS - REIMBURSABLE
Oper: Relay-Accessory Switch Replace — "W" Series Trucks
SP-14088-A-66
Time: 0.8 hrs.

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