BENDIX TCH-008-026 User Manual

Technical Bulletin

Bulletin No.: TCH-008-026 Effective Date: 12/15/95 Cancels: NA Page: 1 of 1

Subject: AD-4 Double Terminal Heater & Thermostat End Covers -

Changeover To Single Terminal Style

General

Those customers desiring to change over from a double terminal heater and thermostat to the single
terminal version of the AD-4 end cover can do so with minor rewiring of the heater and thermostat.
With the exception of the two heater and thermostat terminals and the related wiring, the single and
double terminal AD-4 end covers are virtually identical and totally interchangeable.

Changeover – Rewiring Procedure

After replacing the AD-4 double terminal end cover with the single terminal version, the following
procedure can be used to make the wiring modifications. For information on replacing the end cover
assembly, see the Disassembly and Assembly sections of Service Data Manual, SD-08-2407.

1. Turn the vehicle’s ignition switch to the OFF position.

2. Park the vehicle on a level surface and prevent movement by means other than the brakes.

3. Drain all reservoirs to 0 p.s.i.

4. Locate the two wires which were connected to the original, double terminal end cover.

5. Using a volt-ohmmeter or a test light, determine which of the wires conducts power and which is
connected to ground. Note, if using a test light, it will be necessary to turn the ignition to the ON
position while performing this operation. After identifying the wires, return the ignition switch to the
OFF position.

6. Connect the wire identified as the power wire to the single terminal of the end cover’s heater and
thermostat assembly. Connect the ground wire under the head of one of the eight bolts that
secures the AD-4 end cover to the housing.

7. Secure the wiring every six inches using tie wraps.

8. Using the “Operation & Leakage Tests” section of Service Data Manual SD-08-2407, test the

operation of the heater and thermostat and its wiring.