Electrical - Installing Trailer Brake Controller
Date: March 9, 2007Order No.: T-B-31.19/07d
Supersedes: T-B-31.19/07c dated May 23, 2006
Group: 31
Revision History
Revision Date Purpose
d 3/9/07 Applicable Models, Rear SAM Part No.
and Adapter Harness Location Updated
C 5/23/06 Applicable Models Updated
b 2/2/06 Procedure, Wire Description and Part Number Updated/Adapter Harness Information Included
a 12/12/05 Wire Description and Part Number Updated
- 6/2/05 Initial issue
SUBJECT:
Model 164.122/175/177/186/822/871
Installing Electric Trailer Brake Controller
If you receive customer inquiries regarding the need for an electric trailer brake controller in the above model vehicles, the following guide is provided.
Note:
There are various makes and models of brake controllers on the market and none have been tested or approved for use by Mercedes-Benz. If you choose to nonetheless install an unapproved aftermarket brake controller, we strongly suggest that all work of this type be performed in strict accordance to the installation instructions and set up procedures as supplied by the brake controller manufacturer.
Installation of electric trailer brake controllers or any damage to the vehicle caused by their use is not covered by the Mercedes-Benz warranty.
In connection with the installation of such devices, please note the following.
1. Check the installed rear SAM. If a rear SAM with part number A164 540 78 45 or A164 540 88 45 is currently installed, a new rear SAM must be installed and version coded. The current part number is listed in the parts information section below. The cost of this update is not covered by warranty.
Note:
Some vehicles without a factory trailer hitch are equipped with a rear SAM that requires replacement with a different rear SAM if trailer brakes are to be retrofitted.
2. Locate plug X58/28. This contains the four wires needed for the electric trailer brake controller.
Refer to the table for wire description.
a. Up to December 2006 production, X58/28 (Figure 1 green plug) near the rear fuse box F4 (Figure 1). Plug may be tie wrapped to harness below Rear SAM.
b. As of December 2006 production, X58/28 (Figure 2, green plug) near the diagnostic connector X11/4 (Figure 2). Plug may be tie wrapped to harness above connector X11/4.
Note:
Most electric trailer brake controllers specify that the power supply must be wired using a self resetting circuit breaker. Follow the instructions supplied with the electric trailer brake controller.
Note:
The above variation in wire colors depends on production date of factory harness and or installed accessory harness.
Warning!
The electric trailer brake controller must be adjusted according to the instructions supplied with the electric trailer brake controller, which requires the trailer be connected to the tow vehicle.
Adapter Harness for X58/28
In order to assist in the installation of an electronic brake controller, an adapter harness which plugs into the vehicle's X58/28 connector may be built. This adapter harness can then be run to the installed location of the electronic brake controller. The parts required for this adapter harness are specified in the parts information section below and consist of a green female connector housing, a 0.75sq mm pin, three 2.5sq mm pins and four lengths of wire (Figure 3).
Note:
All four wires need to run from the X58/28 connector to the installed location of the electronic brake controller, which can vary depending on customer preference.
Parts Information