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TSB 08-33-96

Trailer Tow Wiring Information

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Date: Oct. 11, 1996

Models: 1994 - 1997 (BR) Ram Truck

Discussion:

Chrysler Corporation has offered optional trailer tow packages on all 1994 through 1997 Dodge Ram Trucks and has made trailer tow packages available through Mopar for vehicles that were not built with the trailer tow package. Several changes to the trailer tow wiring have occurred since the Dodge Ram Truck was introduced. This bulletin identifies these changes and provides part numbers for the trailer tow wiring harnesses, relays, and flashers. In addition, this bulletin identifies the part numbers for the Mopar trailer tow packages required to adapt trailer wiring to a vehicle that did not have the trailer tow package installed as original equipment from the factory.  

TRAILER WIRING IDENTIFICATION

The trailer tow wiring 7-terminal connector (located on the receiver hitch), is configured with the following circuits:

 
CAV CIRCUIT FUNCTION
1 Z13 12BK GROUND
2 B40 12LB TRAILER TOW ELECTRIC BRAKE OUTPUT
3 L76 12BK/OR TRAILER TOW RELAY OUTPUT
4 A6 12RD/TN FUSED B(+)
5 L63 16DG/RD LEFT REAR TURN SIGNAL
TRAILER TOW
6 L62 16BR/PK RIGHT REAR TURN SIGNAL
CONNECTOR
7 L1 16VT/BK BACK-UP LAMP SWITCH OUTPUT
FIGURE 1:   7-Terminal Trailer Tow Connector

Some of the circuits of the 7-terminal connector may be somewhat difficult to identify. The following explains those circuits that may be somewhat confusing.

Cavity-2   Trailer Tow Electrical Brake Output

This circuit provides a connection between the trailer tow 7-terminal connector and an electric trailer brake system. An electric trailer brake kit was introduced at the beginning of the 1996 model year. The kit includes an electric trailer brake jumper with unterminated leads, heavy duty flasher, a 7-terminal to 4-terminal adapter, and an instruction card. The instruction card identifies that the trailer brake circuit mating connector is located in the instrument panel near the steering column. This kit is utilized throughout Chrysler Corporation on several different vehicle applications and on the Dodge Ram truck, the mating connector can be located behind the fuse block near the dash panel, not near the steering column as stated by the instruction card.

Cavity-3   Trailer Tow Relay

The trailer tow relay circuit provides a 30 amp circuit (40 amp for 1996 and 1997) to feed the trailer's taillpark lamp circuit. This circuit is connected to fuse 7 in the Power Distribution Center (PDC). The relay is also located inside the PDC. The relay is energized anytime the park lamp switch is turned ON. The park lamp switch provides the necessary current to operate the trailer tow relay coil.

WARNING: IT IS IMPERATIVE THAT THE TRAILER TOW RELAY BE UTILIZED WHEN OPERATING THE TAILIPARK LAMPS ON THE TRAILER. THE CURRENT CARRYING CAPACITY OF THE HEADLAMP SWITCH IS LIMITED TO THE LAMPS UTILIZED BY THE VEHICLE ONLY.

Cavity-4   Fused B+

This circuit provides a 30 amp (40 amp for 1996 and 1997) circuit for operating electrical circuits on the trailer. This circuit is connected to fuse 7 in the PDC. This circuit does not contain any isolation device between the 7-terminal connector and the fuse. Current will not be interrupted to this circuit with the ignition switch in the OFF position.

Cavity-1, Cavity-5, Cavity-6, and Cavity-7 are self explanatory.

MOPAR TRAILER TOW PACKAGE

If the Ram Truck does not have the trailer tow package installed at the factory, the truck wiring can be converted so that trailer wiring can be connected to the truck's wiring system. The following trailer tow wiring harnesses are available from Mopar.

NOTE: - THE 4-TERMINAL TRAILER TOW WIRING PACKAGE SHOULD NOT BE USED WITH TRAILERS THAT HAVE ADDITIONAL RUNNING LIGHTS OTHER THAN THE REAR TAIL/PARK LAMPS.

For additional information regarding Mopars trailer tow packages, refer to the 1996 Mopar Accessories P.A.D. Application Guide & Price List.

TRAILER TOW PACKAGE COMPONENTS AND ACCESSORIES

The following components and accessories can be ordered through Mopar to aid in trailer wiring connections.

Notes: 

Policy:    Information Only

From a 1995 issue of the Star Center News:

1994/95 DODGE RAM (BR) TRUCK TRAILER TOWING REQUIREMENTS

Both the factory installed trailer tow harness and the Mopar, Parts trailer tow harness do not require the trailer tow harness overlay kit. The necessary relay is in the PDC when the harness is installed at the factory, and the Mopar Parts trailer tow harness has the relay built into the harness. The overlay kit is erroneously listed in the 1994 New Dodge Ram Cummins Turbo Diesel Owners Manual(Publication No. 81-326- 9422), the 1995 Dodge Ram Pickup Truck Owners Manual (Publication No. 81-326- 9522) and also on an addendum card (81-016-9422).


Thanks to Bob Bergevin and Barry Drodge for supplying this TSB information

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This page was edited on: May 3, 2004