o/d off light blinking and no speedo when trailering

[prostang85]

I have a 99 F-350 crew cab dually 2wd 7.3. When i go to tow my trailer, o/d off light blinks and speedo does not work. I have had this happen on two different trailers. when unhooked from trailer everything is fine. Have tried with o/d off and on does it either way. Speed sensor in rear has been changed, torque converter has been changed to a billet one with a 300 rpm lower stall and still same problem. HELP PLEASE prostang@optonline.net

[Grebesbakery]

Had same problem, i disconnected the trailer breaks under the dash and replaced the stop/hazard fuse that blew. Hasn't done it since......have no clue why it happened

[prostang85]

Will try that. Thanks.

[jesilvas]

Sounds like you just masked the problem.
Personally, I'd fix it and check all your trailer wiring as well as your brake controller's.

[prostang85]

Have checked trailer on another truck and no problems. Checked all connections on brake controller all good. Have been told to check gem module on back of fuse panel. So that's next

[jesilvas]

I mean the wiring on your truck

My Samsung SGH-I997 made me send this.

[prostang85]

Truck factory wired