Hi all,

I installed a new wiring harness from American Autowire for my 59. The harness is the “classic update harness”, so everything is pretty much there with a few possible future upgrade provisions. The install was pretty straight forward with detailed instructions and labeled wires.

anyway I’m 98% finished but I am having trouble with the rear indicators when the park/head lights are turned on. The indicators start to flash out of sync from front to back and I can’t get the “bright” indicator filament to work, the other filament just keeps doing the flashing. I contacted American autowire and they seem to thing it is a earth/ground problem, so today I removed all ground connection and cleaned, and replaced. I also added a frame to bed connection to be sure that the loose bed bolts are not causing a poor ground.

i was having a similar issue with the front (indicator filament not flashing) but I reversed the connections to the park light pig tails and it fixed the front issue and the lower filament started flashing.



the tech told me that the lights ground through the metal surround to the bed so I tried a lead from the battery negative and also tried alligator clamps from chassis to metal surround with no luck.

what did seem to work was just keeping one wire plugged in and touching the other on the bed (see pic below)

last night I did try using the alligator clamp on the light surround and touching to the bed and got some results illuminating the indicator filament but it only did that every so often not every time. I did the same thing today and got nothing. Not sure if some component fried but all fuses are good.

I'm at a loss at the moment and I have no idea where to look next. Any help would be appreciated. Thanks!

New bed to frame ground


alligator clamp to frame


alligator clamp to light surround


touching one wire to bed seem to work, but still not illuminating indicator filament (the one lower in the globe)


cable direct from batt neg to metal light surround


Filament lower in globe is brighter and used for flashing. The brightness is needed when park/head light or tail lights are on to indicate brighter than the tail lights.

 

You have the bed grounded to the frame but is the frame grounded to the battery?
The other thing I would check with a test light is do you have power to each side for turn / stop?
Do the same for tail lights.
Once you know you have 3 wires (L / R / Run) to the rear that do that can you then check at the light housings & bulbs.
That is how I would go about getting this to work.
BTW are you sure the pig tails are good?
What if the contacts turned a little in the socket and would only hit 1 of the contacts of the bulb?
Yep I have see this happen and new bulbs can be bad also.
Dave ----

 

Fuzzface-

The battery is grounded to the frame and the cab. the block is also grounded to the frame.

the front and rear pigtails are new from Macs because I suspected the factory ones were worn out.

Thanks for your advice, I’ll do those checks.

 

I found the issue.

the new pigtails were a bit loose in the socket so I epoxied them in (stop them pushing out when inserting globe). Some of the epoxy got between the two metal surfaces and insulated them. The metal pigtail couldn’t ground to the light surround.

although that fixed that issue, the flasher was still intermittent and twitchy when bumped, so I added a ground to each light which completely solved the issue. Just have to add some corrugated tube to tidy the wire up.

 

How were the original sockets held in place?

 

They were pressed in. I had to use a punch to knock them out.

 

Could the new ones be soldered in.

 

Yeah guess so, I’m not sure if the heat would get to the plastic components and wires causing them to melt. I ended up crushing them slightly in the vice and they held pretty darn tight, then I epoxied for good measure.