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1982 FJ60 Landcruiser

Upgrade to leds on dash/external.

When I press brake pedal, both turn signals come on 10% brightness. On the dash and on all 4 corners of the vehicle outside.

Did a bunch of tests

jump wire from both tail brake light grounds direct to to battery ground, still reproduces. (test for floating ground)

Jump wire to bypass brake switch, still reproduces. (Test for "leaking" brake switch)

Removed both rear 1157 brake bulbs, turn lamps still lit. 12v at stop 7v at turn.

Pretty sure what I have is a short from brake circuit, going through corrosion and into turn signal.(jump ground on tail brake light plug to battery -, no change, remove tail stop bulbs , no change)

Any cool tools and tricks to find it?

Have test light, multimeter, power probe 4 and fox and hound short and no continuity tester.

Any clever way to find the short?

Any good tests I should perform to verify or disprove my assumption?

Maybe fox & hound run tone into turn wire, trace back and look for volume to go down where the resistance is, probably at the short?

Eric Brown - Cal
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2 Answers2

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The most likely fault, is a bad ground connection on the rear light clusters.

When you put power onto the brake lamps, the voltage on the ground side of the lamp is raising enough to push current in reverse through the turn/indicator lamps.

If this is correct, then if you remove the brake lamps and press the brake pedal, the turn lamps shouldn’t illuminate.

Try adding another wire directly from the ground side of the brake lamp to a clean connection on the body and see if the fault goes away.

HandyHowie
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I couldn't find a clever test to locate the short, so I started trying to reduce the circuits into smaller pieces I could test in isolation.

First I modified the harness so I could disconnect the riskiest sections Non factory mods.

First as the most likely was a hacked-in 4-way trailer plug that plugged into and powered a 6 way trailer plug on the bumper.

The next most likely culprit were mods for turn signals in Led Headlights.

I removed the butt splices on the trailer wiring and replaced them with crimp spade terminals.

I disconnected that whole section, and the problem went away. Plugged them back in till it occurred again, identifying the wire from the left rear stop light to the 4-way plug.

Disconnected the plug from rest of trailer wiring, and it still occurs. I suspect corrosion in the plug and am going to replace it with a new one.

Eric Brown - Cal
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