Specifications & Measurements

  • Hitch ball size: 1 7/8  or  2 inch ball.
  • Maximum hitch height is specified as 25 inches
  • Measured natural height of trailer hitch ball receiver:  19 inches ground to bottom ( stopped by a U Haul to get this number.  It applies to the hitch seen in the diagram above.  Simpler version without auto safety break will be slightly lower. 
  • Height of the top of the square of my hitch receiver is: 14.5 inches

A rise of about 3 inches would put the hitch at the natural height.  Will use the bigger ball.


Research Links



4way1 4flat-wiring1 

My best guess is that the converter consists of some connections or resisters + connections at a minimum.  Will enter what I find here later.

Auxiliary Links

The trailer hitch design height used worked for a 2100 mile journey.  Grateful that is over.  Two Arizona trips and a trip to Washington D.C.  Ouch.  Now if I could only find a used Uhaul trailer.  I really like this 2 axle trailer.

Chapter 2

The right hand blinky function would not work on the trailer I purchased after I connected it the second time.  Turned out the round to flat adapter must have deformed when I shoved in the adapter.

Debug Sequence

  • Shake everything – no help
  • connected jumper cable from chassis to trailer – no change
  • Drove around the block – contrary to what was suggested the ground does not go through the metal hitch
  • checked all the functions – found that only the right blinky / braking display was affected – running lights were unaffected
  • Used multimeter to see that the right hand Turn / Stop function was the only connection out of the round-to-flat adapter with no signal – Green Wire
  • Went and bought replacement fuses – last time I had a problem it was the fuses – Roger helped debug with his buzzy tool – replaced fuse – no change
  • Used a cheap battery charger set to 6 volts to show that trailer wiring was not involved – connected to the various pins and saw all wiring good
  • Now suspect flat adapter back to fuse box.  Used my second adapter – Problem solved.  All functions go.


Fuse Box Map

Actual fuse box

Econoline E-150 fuse box map


Fuse/relay location Ampere rating [A] Description
1 Not Used
2 Not Used
3 Not Used
4 10 PCM Keep Alive Memory, Instrument Cluster
5 10 Right Trailer Turn Signal
6 10 Left Trailer Turn Signal
7 Not Used
8 60 I/P Fuses 5, 11, 23, 38, 4, 10, 16, 22, 28
9 30 PCM Power Relay, Engine Compartment Fuse 4
10 60 Auxiliary Battery Relay, Engine Compartment Fuses 14, 22
11 30 IDM Relay (1998 1/2 Vehicles)
12 60 Engine Compartment Fuses 26, 27
13 50 Blower Motor Relay (Blower Motor)
14 30 Trailer Running Lamps Relay, Trailer Backup Lamps Relay
15 40 Main Light Switch
16 50 RKE Module, Auxiliary Blower Motor Relay
17 30 Fuel Pump Relay, IDM (Diesel)
18 60 I/P Fuses 40, 41
19 60 4WABS Module
20 20 Electric Brake Controller
21 50 Modified Vehicle Power
22 40 Trailer Battery Charge Relay (Modified Vehicles Only)
23 60 Ignition Switch
24 Not Used
25 20 NGV Module
26 10 Generator/Voltage Regulator (Diesel Only)
27 15 DRL Module, Horn Relay
28 PCM Diode
29 Not Used
A Not Used
B Not Used
C Trailer Backup Lamps Relay
D Trailer Running Lamps Relay
E Trailer Battery Charge Relay
F IDM Relay
G PCM Relay
H Blower Motor Relay
J Horn Relay
K Fuel Pump Relay, IDM Relay (Diesel)
Categories: Mechanics


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