Hello guys, it has been a while.

I am here with a very odd problem on my 1990 LWB GEN I. My problem is with the factory horn, both connected and only the top one works making the Monty sound like a little clown car, damn it!!!.

I ran a series of test to see if I could isolate the problem.

First, each of the horns has a pair of cables (black with red lines around the circumference of the cable), these are a Y split from two cables, (positive and negative (GND)), from the main wiring harness which runs along the fender wall on the driver's side. Each cable has a split to bring negative (GND) or positive to each of the horns.

Testing:
I have both pairs of cables disconnected from the horns, and the ignition switch in the ON position. I marked the pair of wires as set#1 and set#2 to make the identification easier.
I selected to use the top connector of each of the horns to connect the cable with power, they are not marked as + or -

- Using pair #1 on top horn
- I connected just the power cable using the top connector.
Ôùï On set #2, I checked both terminals with my testing light and I had power just on the power cable.
Ôùï I connected the negative (GND) from set #1, checked set #2 and both cables have power.
Ôùï Top horn works.
- Using set #1 on bottom horn.
Ôùï I connected the power cable and on set #2 I have power on the power cable only.
Ôùï I connected the NEG (GND) and set of wires #2 have power just on the power cable
Ôùï Horn doesn't work.
******
- Using set #2 on top Horn
Ôùï Connected power cable only and set #1 has power ONLY on power cable.
Ôùï Connected negative (GND) cable and set #1 shows power on both cables.
Ôùï Horn doesn't work.

- Using pair #2, on bottom horn:
- I connected the power on the bottom horn on the top plug.
Ôùï Checked set #1 I got power on the power cable.
Ôùï From set #2 I connected the NEG (GND) and on set #1 I got power just on the power cable.
Ôùï Horn works

I took apart all the wires from the horn all the way yo the Y split and the cables are in perfect condition, no cracks, no toasted cable shielding, and the same for the rest of the cables in the wiring harness.

This truck had an alarm system installed but from under the dash the cables from the horn enter the loom and they were not spliced for the alarm installation.

Have you had a similar experience.

What was your fix?

Thanks,
Javy