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Old 09/27/09, 03:23 PM   #1
Sbolt19
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Brake & Flasher Lights not working right

I found out today that my driver brake & blinker lights are not working, but there is something funny going on past that. I am not any good (and I stress that with double underlines) at electrical. It just does not register at all with me. So, here is my problem, and it is easier to list it all out.

With Lights Both On & Off and High or Low Beams
TAIL LIGHTS
Driver Blinker - NO
Pass Blinker - Yes
Driver Brakes - NO
Pass Brakes - Yes
Driver Flasher - NO
Pass Flasher - Yes
FRONT PARK LIGHTS
Drive Blinker - Yes
Pass Blinker - NO
Drive Flash - Yes
Pass Flash - Yes

All lights come on when I turn my headlights or parking lights on. My guage lights all work except the pass blinker and that only works when I have my flashers on.

So with that, I know I have all working lights, which I double checked every bulb and they are all good. I have also checked the connections at the brake switch and one side looked bad so I replaced the female spade connector and tried it all again. Same results. I checked both flasher switches (silver canisters in the wiring harness) and both had good connections. Where do I go from here?
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Old 09/27/09, 04:54 PM   #2
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On the rear it looks like the driver side is the common denominator. They all use the same element in the bulb. I'd suspect a bad bulb or bulb connection. The bulb ground is good cause the taillight works. The pass front may have a bad bulb, corroded terminals, or lost ground.

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Old 09/27/09, 05:20 PM   #3
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One key thing here is that the pass side turn indicator only works with the hazard lights. That tells me something is wrong with the turn signal switch. That would explain the front light and indicator. The rear light problem could be related but definitely check the bulb first.

74 Sport U151, 5.0 must-plorer EFI, C4, PS, front discs, twin sticks, 3.5" susp/1" body, 33's, 4.11's, ARBs, Hickey Sidewinder, cobra hydroboost
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Old 09/27/09, 05:33 PM   #4
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since some turn sig lites work,some flasher lites work ,turn and flasher units are ok.did you check left rear bulb with ohmmeter?if not do it or just replace the bulb.also check wiring to left rear.as for front,check turn sig sw.a little wd in left rear socket to clean it.I gota to type faster.

Last edited by oleguy74; 09/27/09 at 05:54 PM..
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Old 09/27/09, 08:24 PM   #5
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Quote:
Originally Posted by Viperwolf1 View Post
That tells me something is wrong with the turn signal switch. That would explain the front light and indicator.
This is actually the second time that I have had this problem. It did it about two years ago and I thought the turn signal switch in the steering wheel was bad so I replaced it and still had the same problem. The funny thing about that was after I replaced the turn switch and another week or so of trouble shooting, the problem went away on it's own and didn't pop it's ugly head up until about a week ago. Now, wether I did something when tracing out last time or not and it inadvertently fixed it, I don't know.

I will check the bulbs, grounds and the terminals again tomorrow and see if there is a bad something.
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Old 09/27/09, 09:07 PM   #6
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You can check continuity through the switch with an ohmmeter. Tell me what year the column is and I can tell you which wires to check at the connector.

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Old 09/28/09, 01:28 AM   #7
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Make yourself a couple of jumper wires (bare or with alligator clips or whatever) and ground the light sockets on the driver's side to the body in a known good grounding spot. Heck, run the front one to the engine if you want. That way you're sure. The rear can run to any good screw on the body.
See if that changes anything.

Paul
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Old 09/28/09, 10:24 AM   #8
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Quote:
Originally Posted by Viperwolf1 View Post
You can check continuity through the switch with an ohmmeter. Tell me what year the column is and I can tell you which wires to check at the connector.
It's a 72, but I put a Centech harness in it about 10 years ago and have since replaced the blinker switch in the steering wheel with the one from JBG
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Old 09/28/09, 11:23 AM   #9
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I'm not sure if the old Centech wiring used the same colors but the wire colors on the turn signal switch side of the column connector should.

'72-'73 Column Connections
Blue=12v from turn flasher to turn switch, circuit #44
white-blue=right front turn and indicator lamp, circuit #2
green=right rear brake and turn lamp, circuit #282
green-white=left front turn and indicator lamp, circuit #3
yellow-black=left rear brake and turn lamp, circuit #283
red-black=12v brake switch to turn signal switch, circuit #810
yellow=12v headlight switch to horn switch, circuit #460
blue-white=horn switch to horn, circuit #482

Disconnect the half-moon column connector and get the column side of it in a position where you can see the wire colors and attach the ohmmeter leads to them. To check the right front continuity flip the switch to the right turn position and attach one lead to the blue wire and one to the white wire. Resistance should be very low (less than 1 ohm). To check the rear left continuity flip the switch to left turn and connect one lead to the blue wire and the other to the yellow-black wire. Again look for 1 ohm or less. With the switch in the neutral position you should have continuity between the yellow-black wire and the green-white wire. If any of these tests shows an open circuit the switch or wiring in the column is bad. If all the tests show good continuity the problem is not in the switch and is closer to the bulbs.

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Old 09/28/09, 07:46 PM   #10
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I had a similar problem on my 72 I recently picked up. What ended up fixing the problem was replacing most all the bulbs, and spraying some electrical contact cleaner into the socket that comes from the steering column to the loom. moving that connector would make some lights work and others not.. a bit of electrical spray and new bulbs and I'm stylin. That was after I took the entire loom out and checked it and re-fixed the ugly tape splices from the PO. There are diagrams available, download them and print them out, they will help understand what goes where. good luck
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Old 10/08/10, 11:32 PM   #11
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What did the OP do to fix the problem?
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Old 10/10/10, 05:58 PM   #12
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The emergency flashers use the tailight filament in the bulb both front and rear not the brake/turn signal filament. That is why they work. The turn signals have thier own filament. Sounds like you have ground problems at the individual lights/circuits.
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Old 10/10/10, 06:43 PM   #13
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Quote:
Originally Posted by patterdale View Post
The emergency flashers use the tailight filament in the bulb both front and rear not the brake/turn signal filament. That is why they work. The turn signals have thier own filament. Sounds like you have ground problems at the individual lights/circuits.
Nice try but no. Hazards use the brake/turn wires and filaments.

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Old 10/11/10, 10:52 AM   #14
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I've got a similar problem in my 75 F250. Driver blinker and brake light haven't been working.

Replaced the turn signal switch, didn't help. Replaced the sockets, bulbs, and checked the grounds, power to the bulbs (using a circuit tester), and finally the rear left turn signal and brake light work. (I actually think it was because I cleaned some of the plugs under the hood.)

It has worked on and off. Sadly, when I jiggle the wire loom under the hood it got it to start working.

It's gotten to the point that it works just about all the time. Probably due to cleaning the connector plugs. EXCEPT when I have my headlights on. I'm going to replace the headlight switch and see what happens, as some have suggested that.

My message is that most people point toward the turn signal switch first, but I don't think that's always the case. Next--or first for some--are the grounds. I agree. And test the power all along the wires to see if you're getting juice.
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Old 10/11/10, 11:59 AM   #15
Viperwolf1
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Quote:
Originally Posted by 70 sport WA View Post
I've got a similar problem in my 75 F250. Driver blinker and brake light haven't been working.

Replaced the turn signal switch, didn't help. Replaced the sockets, bulbs, and checked the grounds, power to the bulbs (using a circuit tester), and finally the rear left turn signal and brake light work. (I actually think it was because I cleaned some of the plugs under the hood.)

It has worked on and off. Sadly, when I jiggle the wire loom under the hood it got it to start working.

It's gotten to the point that it works just about all the time. Probably due to cleaning the connector plugs. EXCEPT when I have my headlights on. I'm going to replace the headlight switch and see what happens, as some have suggested that.

My message is that most people point toward the turn signal switch first, but I don't think that's always the case. Next--or first for some--are the grounds. I agree. And test the power all along the wires to see if you're getting juice.
Key thing to remember-You need a difference in potential (voltage) for current to flow.
Attached Images
File Type: jpg bad ground.JPG (25.3 KB, 17 views)

74 Sport U151, 5.0 must-plorer EFI, C4, PS, front discs, twin sticks, 3.5" susp/1" body, 33's, 4.11's, ARBs, Hickey Sidewinder, cobra hydroboost
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