Electrical - Trailer Brakes Won't Release In Reverse

T-SB-0033-11

May 5, 2011

Trailer Brakes Will Not Release While Vehicle Is in Reverse

Service Category
Vehicle Exterior

Section
Lighting (ext)

Market
USA





Applicability

Introduction

Some 2010 and 2011 Tacoma vehicles built at TMMBC with the Tow Package option (accessory code TO) may not have a reverse input present at the 7 pin towing connector BKUP terminal due to a missing Backup Lamp Relay (B6).

The Backup Lamp Relay B6 provides a reverse input signal at the BKUP Terminal of the 7 Pin towing connector.

If this reverse signal is not present the vehicle may exhibit an inability to move in reverse when attached to certain types of trailers or inoperative reverse lights on the trailer if it utilizes the reverse input on the 7 pin trailer connector for that function.

Please use the following repair information to address this condition.

Production Change Information





This TSB applies to 2010 - 2011 Tacoma vehicles equipped with Tow Package (Accessory Code "TO") BEFORE the Production Change Effective VIN shown.





Warranty Information





Parts Information

Repair Procedure

1. Verify the reverse lights on the vehicle (not trailer) work normally.

If the vehicle's reverse lights do not operate properly this TSB does NOT apply. Refer to the applicable Repair Manual for diagnosis.

2. Verify the vehicle is equipped with "TO" Tow Package accessory via TIS.

A. Choose Vehicle Inquiry tab, then enter VIN, and click on Lookup.





B. Under Accessories, look for TO: Tow Package.





3. Remove the glove compartment and examine the location of the Backup Lamp Relay B6 as shown in Figure 2.

4. If a Backup Lamp Relay is not present install one in the indicated location.

5. Reinstall the glove compartment.

6. Verify normal operation of the vehicle's tail lamps.

7. If a relay was installed, follow the procedure below to verify the reverse input at the 7 pin trailer connector.

A. Turn engine OFF.

B. Make sure ignition is in the "IG-ON" position and the engine is NOT running.

NOTE

Ignition should be in the "IG-ON" position, NOT "CC-ON".

CAUTION

Do NOT start the engine during this procedure.

C. Set the parking brake.

Make sure the vehicle will NOT move, use wheel chocks if necessary.

D. Place shift lever in Reverse.





E. Have an assistant verify battery voltage at the 7 pin towing connector center terminal B/UP pin 4 and ground with voltmeter. Pin 4 is illustrated in Figure 3.

NOTE
Terminal locations are also listed on the towing connector cover.