Website Home | Info & Posts | Club Membership | Eagle History | Contact Us


The new administrator has been establishing a plan for the update of this site.

#### The forum is availabe for reading and posting. ####

For update activity/status click on this thread.

Conversion of 5 Wire to 4 Wire Taillight system for Towing

This forum will archives technical threads that are unique to Eagle Buses. There will be one thread for general comments, but the technical threads will be locked. The intent is to have a repository for detailed technical information that can be of prime importance to an Eagle Bus Owner. New threads can only be created by the forum administrators.

There are often threads on other bus forums that discuss this subject. Indeed there is an active thread on BCM right now.

In 2009 I experienced my upteenth failure of a commercially available converter (photo below).

After Market Converter.jpg

That prompted me to fabricate a homebrew converter made with automotive style relays. I had observed information/systems built by Craig Shepard, Sean Welch, and Jack Conrad. Ultimately I documented my conversion in an article published in Bus Conversions Magazine. I have uploaded that article on our website:

As background information, Eagles (and most buses) have turn signal lights separate from the brake lights. This results in a five wire circuit. Virtually all trailers and cars have the turn signal lights combined with the brake lights (4 wire system). As a result, a converter is required. The circuit designed with relays is much more reliable than most commercial converters. It is fairly easy to construct and the parts are fairly inexpensive. Indeed, the original Eagle relays can be used.

The article has two wiring diagrams. I have attached the diagram I made for my system.
Trailer 5 to 4 wiring.pdf
(261.28 KiB) Downloaded 376 times
Jim Shepherd
Evergreen, CO
'85 Eagle 10 with Series 60 & Eaton AutoShift 10 speed transmission - not at all fancy, but fully functional
Bus Project pages:
Email: Note: Email sent to the this address requesting technical advice will not receive a response
User avatar
Posts: 2303
Joined: Wed Oct 08, 2008 4:39 am
Location: Evergreen, CO

I burned out several of those before I smartened up and just added another pair of lights to all my trailers.
Joe Laird
'78 05
Sioux Falls, SD
User avatar
Club Member
Club Member
Posts: 485
Joined: Tue Oct 14, 2008 12:11 pm
Location: Sioux Falls, SD

Return to Technical Archive

Who is online

Users browsing this forum: No registered users and 1 guest