wiring 50 merc

H

Halvor

Member
Where would be a good place to start looking for a solution to this....When I turn the ignition on ....the parking lights come on and the tail lights come on. Everything works fine i.e., the turn signals , brake lites head lights high and low beam.
I think its in the brake lite switch but sure could use some help.
 
Something is cross wired obviously. Lights are not wired directly through the switch. Brake light switch should only affect the brake lights. Check your wiring diagram carefully and re-trace everything.
 
Do you have stock wiring or an aftermarket setup?
Trace back your lights and find out where they pick up power. Then see if that is where your switch is energizing those lights. As Lawson mentioned trace it against your wiring diagram. Keep notes or a diagram of what you find, it can get confusing
under the dash.
 
Somehow you have a wire from the ignition switch going directly to the tail/park terminal on the headlight switch. The headlight switch is never wired through the ignition switch. The headlight switch operates with a constant hot wire so the parking/taillamps can be activated with the ignition in the off position.
 
I'm in the process of rewiring one of my 51s. If you still have the original cloth covered wire in the car you'll likely find a wire shorting to another. The likely place to look would be near the light switch, circuit breaker board, turn signal blinker unit, or in the wiring that routes up into the steering column some where. All ot that wiring is real close together under the dash just above the hand brake control. It is also possible to have an internal problem with an old light switch assembly but they were a pretty good switch plus they are independent of the key switch as was mentioned before so I kind of think in the shorted wire direction. Its hard to tell if you have the park lights on or the turn signal lights when you have wires shorted together. The brake lights are also wired through the turn signal switch in the column.

The old wiring just crumbled away as I removed it from my old Merc. Some folks rewire them with Painless stuff or other aftermarket products but I have been using the original type stuff from MACs. I think his is made by a company in Oregon or Washington State. The stuff from Rhode Island Wire is better but much more expensive.

Kerby
 
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I guess I will try to get to the light switch and see if I can solve the problem.
I truly thank all of you guys who responded....it is nice to know that even tho I am 82 yrs old I can still make sense.

One question tho which wire MIGHT I have connected wrong on the ignition swich ??????

Thanks again
 
When you turn on the ignition switch you power up the engine & fuel quantity guages, the ignition coil, and the hot side of the turn signal blinker switch by connecting them all to the electrical bus through a main (power to the switch) wire. There are several accessories that are also powered up including the radio and the overdrive relay if your car is so equipped. The electrical bus where the circuit breaker panel is, is always hot, key on or off. That blinker switch wire is the only light related item that is turned on with the key switch. The light switch is hot all the time so that you could leave the park lights on with the key removed and the car locked up. Folks don't do that much anymore but some states still had laws on the books about park light use back in that time frame.

Kerby

PS: Just so there is no confusion, the turn signal system actually has the two switches. One to control the turn signals individually and one to blink the lights. I refer to the later as the blinker switch.
 
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