Tow Dolly Wiring

[Pat M]

Good day all,

Attempting to use a tow dolly, I plugged in 4 pin plug with adapter and only my left turn signal worked. Call the manufacturer of the dolly and he stated either it is a ground or RV wiring issues. I cleaned the grounds and tested with a multi-meter for continuity all checked OK on the dolly. Took apart the the 7 point receiver to checked the wiring and I have 5 wires. red wire is the hot wire, white is the ground, yellow is the left turn (strong) signal, brown wire I believe is the right turn (faint) signal and black wire I have no clue. I been trying to find a wiring diagram for a 1999 Monaco Executive or a diagram with colors of wires I have. For all I been reading there should be a green wire? Just wanted to asked before I test every wire tomorrow.

Thank you,
Pat McArdle

[l1v3fr33ord1]

Pat-

Yes, best to test every pin for signal, with a test light (preferably), an analog voltmeter, or a digital voltmeter.

There may be "standard" colors and signal pin locations, but any particular connector or coach may not follow them.

That said, "7-way RV Standard," per this link, is common.

Page 5-159 of the 2001 Executive Owner's Manual (link here) confirms the usual for your coach. That is, it was not wired to a 7-pin standard. Instead, as it came from the factory it had these signals:

Left turn
Right turn
Brake
Parking
Ground

This is common for older coaches. The tow dolly expects these signals:

Left turn/brake
Right turn/brake
Parking
Ground

To make the conversion between a three-wire (LT, RT, Brake) and a two-wire, someone probably installed a three-to-two converter upstream of the hitch connector. You find it by following the wiring from the connector towards the front of the coach. Somewhere within three feet of the connector you will find a block of metal or plastic about the size of a pack of cards. That's the converter. A failed converter will cause the symptoms you observe (it is not the only cause, though). You can get a replacement converter at this link.

[Pat M]

Thanks Mark,

Plugged dolly into my truck (didn't know I had a plug and never used it) all good. Disassemble the 7 pin with 5 wires. Cut 4 way flat from truck and spliced in all wires colors and guessed that black is green, everything worked. Red wire is continuous hot can not find a fuse or where it connects to the battery, it's hot even when I turn off main battery switches. I 'll find it but do not understand why somebody would not put a fuse inline?

Thanks for your response and safe travels,
Pat McArdle