Brake light questions

[txboiler]

Wiring tail light question for you you all. I have the rectangle LED light with the "trailer light adapter" mod that was provided with the complete kit from FFR. The rear parking lights and turn signal lights work but no brake lights on either side. I have gone all through the brake light system looking for obvious lose connection and continuity. No issues identified. Purple brake light wires from the brake switch are connected to red brake light wire going into “trailer light” adapter. Brown wire on the output side of the adapter are connected to the tan wires (tail light feed) going to brake lights (I used the purple wires for light in truck). At the tail light connection I am getting 12 volts with the parking lights and the voltage does not change when the brakes are applied. I checked the voltage at the brake switch and I get 0.47 volts on the orange brake feed wire (seems low). With the brake applied I get 0.45v at the red wire going into the trailer light adapter.

Is the voltage at the red wire correct?
What input voltage does the adapter need in the red wire?
Has anyone seen the trailer light adapters fail?

Thanks in advance.

Brake light adapter.jpg

[jiriza84641]

not sure about the voltage cause I have not tested mine (dealing with a water pump issue). Hook up the lights which are LED and see the light output. That voltage seems too low anyhow to function the lights.

[Jeff Kleiner]

Are the 4 way hazard flashers working?

Jeff

[Lidodrip]

I am not sure about voltages, but my guess is that you could also have a bad brake light switch. I believe the clutch and brake switches are the same (just connected differently) and you could use your clutch switch to rule out a bad switch.

James

[Bob24]

Tie the wires together on the brake light switch and see if they come on. Check the switch with ohm meter. Check the harness where it plugs in to rear harness, one of my wires were reversed in the plug to front harness for the horn.

[txboiler]

The four way flasher are not working either in the front or the back. The individual (Lh or RH) turn singles work on all four corners. Obviously a wiring issue on the DPST switch (I suspect this is it and haven’t dug into that yet, as they worked during mock up but I didn’t label the connection and can’t seem to find this in the instruction manual. I am out of town right now and asked Jennifer to take a picture for me. I will add that to thread later

[txboiler]

Tie the wires together on the brake light switch and see if they come on. Check the switch with ohm meter. Check the harness where it plugs in to rear harness, one of my wires were reversed in the plug to front harness for the horn.

I thought of the switch but ruled it out because I had same voltage on input and out put when brake is pressed. When not pressing brake voltage is only on Input side

[txboiler]

Are the 4 way hazard flashers working?

Jeff

The four way flasher are not working either in the front or the back. The individual (Lh or RH) turn singles work on all four corners. Obviously a wiring issue on the DPST switch (I suspect this is it and haven’t dug into that yet, as they worked during mock up but I didn’t label the connection and can’t seem to find this in the instruction manual. I am out of town right now and asked Jennifer to take a picture for me. I will add that to thread later

[Jeff Kleiner]

The four way flasher are not working either in the front or the back. The individual (Lh or RH) turn singles work on all four corners. Obviously a wiring issue on the DPST switch (I suspect this is it and haven’t dug into that yet, as they worked during mock up but I didn’t label the connection and can’t seem to find this in the instruction manual. I am out of town right now and asked Jennifer to take a picture for me. I will add that to thread later

Mike,
The reason I asked is because the 4 ways and the brake lights are on the same fuse. The fact that neither is functioning tells me that the problem lies in that circuit (turn signals are on a different circuit and fuse). There should be full 12 volts both to and from the brake light switch as well as the 4 way flasher feed. There is not a reduced voltage by design. Pull the fuse and check it's continuity. If it's good then check the voltage on the terminal at the feed side of the fuse. If you don't have that you'll have to trace it back but I suspect that the fuse is blown fuse and your .4 reading is bogus or perhaps a phantom backfeed from the trailer module.

Jeff

[Railroad]

That low voltage can be, ground or power is feeding through a bulb filament.

[txboiler]

I got back in town this weekned and was able to do some more troubleshooting and FIXING.

The first thing I did was traced by back the low voltage on the orange brake feed wire to the fuse/relay box. Jeff Kleiner was correct in his assumption, earlier in the thread, that the fact that the hazard lights not working and the brake light issue were one in the same. I first check the fuse brake fuse and it was intact and I double checked it for continuity.

I then check the "back side" of the fuse/relay panel for loose wired etc. I noticed that the orange brake feed appeared to be backed out a bit. I removed the fuse and pushed the wire back in. The connector seated (felt like seating a pin in the plug), reinstalled the fuse and the brake lights worked. I suspect the low voltage reading was from a questionable connection.