A question for electrical experts (1 Viewer)

[Jonathan Hanson]

Everyone,

Our 1993 HZJ75 Troopy has developed a maddeningly capricious fault. For no apparent reason, both the headlamps and horn/emergency flashers stop working. On a recent trip this caused quite a tense situation when we had to race sunset on a highway.

It's completely random, and will "fix" itself for a while, then go wonky again. This morning I went out to take a look at it, and both headlamps and horn were working. When I came out an hour later, not having touched or started the vehicle, they had quit again. All three fuses (one for each headlamp and one for the horn) are fine, but there is no power to them. Voltage is fine. The running lamps work.

Any ideas would be appreciated, thanks!

 

[rick_d]

Check your grounds. White/black bonds on fenders, cowl, frame, engine etc.

 

[Sundowner]

^ That. Seen it happen before in exactly that way, on both negative- and positive-switched vehicles.

 

[sodafeld1]

more than likely bad earth, loose wire connection or wire has rubbed against something over the years and exposed the naked copper. It happens on old cars.
Trace and track is the path of electricals.

 

[Jonathan Hanson]

Ah, thanks for that . . . I'll do some searching tomorrow.

 

[Jonathan Hanson]

I thought I would resurrect this thread for anyone who might have the same issue. The solution turned out to be quite simple with help from a wiring diagram downloaded from Cruiser Cult, from a hard copy donated by Matt Hickey (thanks!).

It turns out the power feed to both the horn and headlamps comes from a single fusible link at the battery. The connection there was loose enough to cause intermittent failure. The fix took five minutes once found.

 

[HZJ75 FARMER]

It's a bit of a bad design. Kind of defeats the purpose of having a separate fuse for each headlight, when they both come from the one fusible link.