Vintage RV- lights not working with 2019 Tundra but do work with 2006 Tacoma

All - I am up for any suggestions here- Please HELP! - inherited a nice vintage 1983 travel trailer and hooked 7spade connector up to 2019 Tundra- running lights work, electronic brake works, brake lights do not work, left indicator does not work, right indicator blinks twice then does not work. Hooked same trailer up to 2006 Tacoma 7spade connector and ALL lights work correctly (Taco does not have a brake controller). Have pulled modern 2016, 18, 19 RV trailers with the Tundra and all lights worked perfect.

Stumped - tested all output on the Tundra 7place connector with a multimeter and all output is correct at 13V when activated brakes, indicators etc... connected a 7spade tester (from a RV store) that has LED indicators when you press brakes, right turn, left turn etc.. and all output is correct off the Tundra with that tester as well.

Any ideas? is it possible that the 7spade output from the Tundra is not strong enough to properly drive the old 1983 NON-LED filament bulbs? most newer RVs (like the ones I have used with the Tundra in the past) are all LED and much lower wattage bulbs

 

one idea I had was to swap in a few LED replacement buds for the existing 1157 filament bulbs to see if the lower wattage works with the Tundra- have not done that yet

 

Can't really help you... but I have found that our 2019 Tundra EBC is "weird" with our 2019 Winnebago trailer, requiring a higher setting on the controller for the brakes to work correctly than compared to a friends Ford with an internal brake controller or another Chevy with an aftermarket system. To get ours to "grab" correctly, we have to crank the setting up, which then results in the brakes overheating since apparently they have "more power" applied to them when driving down the road, an issue not present with either other truck. Of course, our local dealer said that their checks on the system were fine. They simply couldn't explain why the brakes were getting hot on the trailer when driving down the road with the EBC set to work as instructed on the Toyota and not on either other vehicle.
Not really impressed with the Toyota and it's "wonderful" trailer towing experience - first they removed a true transmission cooler, and now a crappy EBC that has no easy interface to an aftermarket system.

Have you checked for any grounding issues on your trailer? Our 2019 Winnebago had (I replaced them with LED) halogen for the brake/tail/turn and they worked fine.

I've got a feeling that our issue is with the trailer circuitry and it's tie-in to the rest of the electrical system (like the dash).

 

@furban, do a quick test. Use a jumper cable from a good ground on the truck to a good ground on the trailer chassis. It is possible that there is a ground issue on the trailer side of the harness. DO NOT reply on grounding through the hitch.

 

@Windsor - I ran the jumper cable test from connected to the frame on the truck and frame on the trailer - no change- everything the same -

bought two 1157 LED replacement bulbs for two of the filament bulbs on the trailer and tried all the same tests connected to the Tundra, lights all behaved the same, not working correctly, then hooked up the Tacoma with the LED bulbs in there and it all worked perfect as it should.

Any other ideas? @Tracy Perry - do you have any suggestions about how to test for grounding issues on the trailer?

 

Did you happen to replace any of your interior lights with LED bulbs? There have been some who have experienced electrical gremlins like this as the LED’s cause some type of interference. If you have I would try to replace the led bulbs with the original bulbs and see if that doesn’t remedy your problem…..

And if it is not working on the tundra but is working on the Tacoma, if there was a grounding issue it would be on the tundra and not the trailer…..

 

Hook the trailer up to the Tacoma that you know is working. Pull a bulb with the flashers on and test the voltage. Do the same with the Tundra hooked up.

 

Are both trucks running or not running?
Are they both hitched to the trailer tongue?
Are you using a 7 round to 4 flat adapter to the Tacoma?
Are you looking for a reason to tell your wife aftermarket taillights will solve this issue?

 

Both trucks are running in each case
Both are hitched to the trailer tongue in all cases except when I did the jumper cable grounding test with the Tundra, in that case it was not hitched- maybe it should have been? I can try that in the morning
I am not using an adapter, my Tacoma has a 7round connector hookup as well as a 4 place hookup
not looking for any excuses... just want it to work!!!

 

Since your trailer uses the 1157 that tells me the socket walls provide the ground or negative side of the circuit. If your running ligts are working doesn't always tell you the ground is good. The ground can be picked up through the other filament from the other side.
Toss the VOM for now and pick up the lighted handle icepick type of tester with the lead and alligator clip.
My guess is there is a problem with the taillight ground on one or both of the lights. Pull both lights out and make sure the ground is good.
If your trailer brakes are in fact working you have a good ground from the truck.

 

No help with the issue but... Different gen truck, utility box trailer not braked with older filament bulbs, also plays silly beggars if I use my round 7 spade hook up, no issues with the 4 pin. Does your later gen truck still have a 4 pin hook up and if so does it run the RV's lights ok?