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Im installing a seven wire universal turn signal switch on my 54 3600. converted to 12V, all new American auto wire harness. front turn signals work, rear ones both flash at the same time. Ive tried different flashers already, double checked wiring. its all according to diagram. To top it off when I step on brake pedal all signal lights stop working including the front.. Any ideas?

I would put a voltmeter on the switch wire output if you getting both left and right wires out putting voltage and you only have left or right selected then the switch is bad.
Heard it happening on some aftermarket signal switches.


Otherwise you got a wire wrong somewhere.

Other thing to understand are you using separate signals from brake/park. Or are you using signal/brake/park all in one housing brake lights.

Bad grounds can cause lights to act mysteriously.

Note that the switch itself must be grounded through the clamp that's holding it on. I didn't want the clamp scratching my newly painted column, so I wrapped rubber around the column. The switch didn't work, so I ran a separate ground wire from the clamp down to the firewall.

If the switch is grounded OK, you can check that all 4 light bulb sockets are grounded.

The park signal should only come off of the headlight switch, and not run into the turn switch. Are you using single or 2 wire front lights? Single like the OEM rear brakes will tie into the specific turn switch wires and only come on with turns. No front park like the stock look. 2 wire front will have the low side on park lead and high to turn. No ground is needed in the switch being the ground reference comes from each bulb. The switch completes the circuit from batt thru flasher and to the bulbs. Is it a 2 or 3 post flasher? A 3 post flasher has one wire to hot of turn switch for external bulbs, and the other to the bulb inside the switch. A ground source in the switch is used to light up the bulb inside the turn switch if it has one.Sounds like something is kitty wampus with the switch. And there is specific left/right fronts and left/right rears.

Yes I’m using two wire park lights. Three post flasher. I think you are right and it has to be the switch.

Update. And thanks for all your guys help. Changed out signal switch to signal stat 900; not the problem. Rechecked all wiring ( again) and checked all my grounds, not the problem. Call American auto wire tech support, ran through all wiring* and turns out white wire was connecting both lights, cut the wire and all is working. Thanks again to everyone

Rechecked all wiring..... not the problem??????????????

turns out white wire was connecting both lights, cut the wire and all is working.????????? White wire of signal switch or the harness?


Is this an AAW instructions mistake? What is the AAW harness part no.?

The early 60s Napa universal 7 wire I cleaned up and used had the white wire for the brake signal. In the wiring loom I put a white wire that ran from the switched side of the brake to the turn switch. Bench tested and installed. I ordered a new universal turn switch and was not impressed with the cheap plastic chrome. But it had the same wiring color schematic. Standard for some universals?