I have good luck with that CRC electrical connector spray - it cleans, but also lubricates, and is safe on the plastic housings as well. I had an issue with a new boat/trailer this past year that was very similar to yours. On my trailer, there are two ground wires that exit out of the tail lights on the trailer and they are grounded to the trailer. I removed them, scraped down to the paint on the trailer under the washer and that fixed my issue. It was like an intermittent problem.
But yeah, use that CRC stuff from time to time and it seems to keep everything in good working order.
I also bought this gizmo that I carry on my boat keychain and it plugs into the trailer light receptacle on my truck (the 4 pin) and it lights up to tell me if any of those pins are bad (easier than carrying a test light around). This way, at least I can quickly eliminate the truck as the issue.
Not long ago, I also discovered a broken ground strap on my truck down by the firewall. Dealer replaced it. Prior to that, I seemed to go through a lot of bulbs on the truck - that seems to have fixed the issue. So yeah, a bad ground can manifest itself in a lot of strange ways. Trailer lighting issues are a pain.
But yeah, use that CRC stuff from time to time and it seems to keep everything in good working order.
I also bought this gizmo that I carry on my boat keychain and it plugs into the trailer light receptacle on my truck (the 4 pin) and it lights up to tell me if any of those pins are bad (easier than carrying a test light around). This way, at least I can quickly eliminate the truck as the issue.
Not long ago, I also discovered a broken ground strap on my truck down by the firewall. Dealer replaced it. Prior to that, I seemed to go through a lot of bulbs on the truck - that seems to have fixed the issue. So yeah, a bad ground can manifest itself in a lot of strange ways. Trailer lighting issues are a pain.
