WARNING
THE CONTROL MODULE MUST BE MOUNTED WITH THE BACK OF THE UNIT FACING THE FRONT OF THE TOW VEHICLE. MOUNTING THE CONTROL MODULE ON THE SIDE OR UPSIDE DOWN WILL CAUSE IMPROPER OPERATION AND MAY CAUSE LOSS OF TRAILER BRAKES.

The mounted position of the control module should be determined by the installer in conjunction with the vehicle owner's preference.

1. Choose a mounting position within arms reach of the driver. Insure proper clearance exist to accommodate wires and fasteners.

2. Securely install the control module bracket on a solid portion of the dash using the self tapping screws (provided) (Fig. 5). DO NOT mount the control module in the glove box, ash tray or any position which has poor air circulation or unstable riding surface.

NOTE 3 - The mounting bracket is slotted and reversible to provide any mounting angle between 5° and 75° degrees (Fig. 6).

3. Align and secure the control module unit in the mounting bracket using the two screws and star washers (provided) (Fig. 5). The star washers MUST be inserted between the module case and the mounting bracket. Improper placement of the star washers could allow the control module to slip, causing possible loss of trailer brakes.

Wiring the Control Module

WARNING
THE HAYES 81750 CONTROL MODULE IS DESIGNED FOR 12V NEGATIVE GROUND SYSTEMS ONLY! IMPROPER WIRING WILL DESTROY THE UNIT AND VOID THE MANUFACTURER WARRANTY.

NOTE 4 - As of 1992, all Ford vehicles with the trailer towing package are provided with all four wires for the control module to splice into for easy installation.

Proper wiring of the control module is very important due to the sensitivity of the high tech electronics involved. Strict adherence to the Hayes wiring procedure is necessary to insure proper operation of the control module.

NOTE 5 - The manufacturer recommends that all connections be made with insulated, solderless, crimp style connectors.

Read the wiring instructions (Fig. 7) completely before you begin wiring the control Connect the four color coded wires in the following order:

1. The white ground wire must be connected directly to the negative ground terminal of the tow vehicle battery using 18 gauge wire or larger.

2. The blue brake wire must be connected to the trailer brake wire using 12 gauge wire or larger.

3. The red stop light wire must be connected to the non-powered wire of the stop light switch using 14 gauge wire or larger.

NOTE 6 - To locate the non-powered wire it may be helpful to use a 12v test light. Connect one test light lead to ground and the other lead to one of the two stop light switch terminals. The non- powered side of the stop light switch is the one that turns the test light on when the brake pedal is depressed and off when and off when the brake pedal is released.

WARNING
1989-91 FORD BRONCO, ECONOLINE, F-SUPER DUTY & F150 350 SERIES: THE RED STOP LIGHT WIRE MUST SPLICE INTO THE TURN SIGNAL CONNECTOR HARNESS. SPLICING DIRECTLY INTO THE STOP LIGHT SWITCH MAY CAUSE INTERFERENCE WITH OTHER ELECTRICAL SYSTEMS.

WARNING
SOME VEHICLES ARE EQUIPPED WITH SEPARATE SWITCHES FOR TRANSMISSION CONVERTER AND CRUISE CONTROL. THE RED STOP LIGHT WIRE MUST BE CONNECTED TO THE COLD (NON POWERED) SIDE OF THE BRAKE SWITCH. IMPROPER CONNECTION COULD RESULT IN NO TRAILER BRAKES IN THE AUTOMATIC MODE.

4. The black power supply wire carries current for both the trailer brakes and the brake lights. This circuit must be connected with 10 gauge wire or larger and a self resetting circuit breaker (Fig. 8), placed as close to the positive battery terminal as possible.

NOTE 7 - THE MANUFACTURER RECOMMENDS THIS WIRE BE ROUTED AWAY FROM THE RADIO ANTENNA TO REDUCE ANY POSSIBLE AM RADIO INTERFERENCE.

WARNING
THE BRAKE CONTROLLER REQUIRES A CLEAN, CONTINUOUS CONNECTION TO THE BATTERY. THE FINAL CONNECTION OF THE BLACK POWER SUPPLY WIRE MUST BE SURE AND CONTINUOUS TO THE POSITIVE BATTERY TERMINAL. WHEN THE BLACK WIRE IS CONNECTED TO THE CONTROLLER, THE FRONT PANEL DISPLAY WILL FLASH. IF THIS DOES NOT HAPPEN, AN ERROR (INTERRUPTION) IN THIS CONNECTION HAS OCCURRED AND MUST BE FOLLOWED BY A MINIMUM 30 SECOND WAITING PERIOD WITH THE BLACK POWER WIRE DISCONNECTED. AFTER 30 SECONDS RECONNECT THE BLACK WIRE AND MAKE SURE THE FRONT PANEL DISPLAY FLASHES. FAILURE TO ALLOW THIS WAITING PERIOD WILL RESULT IN INCORRECT OPERATION OF THE BRAKE CONTROLLER.

WARNING
DO NOT CONNECT THE BLACK POWER SUPPLY WIRE TO THE FUSE BOX OR ANY OTHER VEHICLE SYSTEM WIRING. THE POWER SUPPLY WIRE MUST BE A COMPLETELY SEPARATE CIRCUIT TO THE CONTROL MODULE. PAY CAREFUL ATTENTION NOT TO REVERSE THE POLARITY OF THE POWER WIRES ON THE CONTROL MODULE. A REVERSE BATTERY CONNECTION WILL DESTROY THE UNIT AND VOID THE WARRANTY.

RELAY SIZE REQUIREMENTS (Relay not supplied)

The secret to powerful, efficient braking is the ability to supply a large current to the trailer brakes. Therefore, the gauge of wire and size of relay is essential to safe, reliable trailer brake control. The relay is a self resetting circuit breaker (Fig. 7) used to protect the control module and the vehicle wiring. The recommended connection for the black power supply wire is with 10 gauge wire and through a self resetting circuit breaker. The relay should be placed as close to the battery as possible to protect all wiring.

The 81750 control module supplies current for the brake coils and the brake lights on the tow vehicle and trailer. Therefore, the size of relay varies with each trailer application. From the chart (Fig. 8), find the minimum relay size required to protect your tow vehicle wiring.

Using the relay size chart (Fig. 8)

1. From the top side of the chart, find the number of trailer brakes on your trailer.

2. On the left side of the chart, find the number of brake light bulbs for your tow vehicle and trailer combined.

3. At the intersection of these two values is the minimum relay size requirement for your application (Example 2).

EXAMPLE 2: The customer has 6 trailer brakes on his trailer and 9 brake light bulbs for his tow vehicle and trailer combined. After matching trailer brake column and the brake light row, he/she finds the recommended relay size for the truck is 40 amps.

NOTE 8 - Each trailer brake magnet is assumed to draw 3 amperes of current and each brake lamp bulb is assumed to draw 2 amperes of current.

WARNING
1992-95 FORD TOWING PACKAGES: FOLLOW INSTRUCTIONS INCLUDED WITH TOWING PACKAGE FOR CONTROLLER WIRING. TOWING PACKAGES COME STANDARD WITH A 30 AMPERE RATED BATTERY FEED WIRE WITH A 30 AMPERE MAXIFUSE INLINE, THIS WIRE, FUSE AND CONNECTOR PIN SHOULD BE BYPASSED, IF THE POWER CONSUMPTION TO THE CONTROLLER IS GREATER THAN 30 AMPERES.

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