1974 Ranchero brake light Problems.

Discussion in 'General Ranchero Help' started by tbird9140, Dec 28, 2020.

  1. tbird9140

    tbird9140 In First Gear

    Messages:
    23
    Hi Guys, you helped me a lot when I had starting problems with my 74 lat month. So, I thought I would pick your brains again with a new, for me, complexing problem. I have turn signals all around and brake light on the passenger side, BUT NO BRAKE LIGHT ON THE DRIVER'S SIDE. Don't say check fuses and bulbs as I have done so. There appears to be no power coming to the right brake light as I have checked the wire when the brakes are pressed. Anyone had this problem, or do any of you have an idea of what might be wrong? I am planning to order a new turn signal switch to see if this is the source of my problem. However there may be a solution I just have not thought about. Help please.
     
  2. 72GTVA

    72GTVA Administrator Staff Member

    Messages:
    9,862
    Location:
    Chesapeake, VA
    There is a connector in the driver side quarter panel that has the wire harness extension for the right side lighting. Follow the wire harness from the grommet where it passes through the inside lower part of the quarter to the connector. You can check for brake light power there to verify it, then check for continuity through the wiring that runs through the harness from left side to right side. If that is good, check the light socket to ensure you are getting contact on the proper 1157 bulb stud, and while you are there check your right side ground connection (black wire on an eyelet screwed to the sheet metal near the right tail light housing).
     
  3. 65restomod

    65restomod In Overdrive BRONZE MEMBER

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    806
    Location:
    Danville,VT left NJ forever
    Also check the connections at the bottom of the steering column for a pin pulled out or corroded
     
  4. tbird9140

    tbird9140 In First Gear

    Messages:
    23
    Thanks 72GTVA and 65restomod. I screwed up in my first post. I said I had no brake lights on the Driver's side. This is true. Then I said " There appears to be no power coming to the right brake light as I have checked the wire when the brakes are pressed." I meant to say no power to the LEFT brake wire, obviously there is power to the right brake wire as it is working. MY BAD. Does this correction change any of the diagnosis procedure you described 72GTVA? Does the connector in the driver's side quarter panel also have the wire extension harness for the LEFT side lighting as this is where my problem is...Left (Driver's) side no brake light? Sorry for the confusion. When I hear back from you with any troubleshooting changes, I will immediately get on it. Again thanks for your help.
     
  5. Hillbilly

    Hillbilly In Maximum Overdrive

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    6,030
    Location:
    Winchester, TN.
    Dan, is there not a harness connector in the cab located under a protective plate driver's side below the dimmer switch ? Bad place for a pin connector as years of wet shoes can cause corrosion in the connector. I have repaired a few 73 and 74's having corrosion in that connection. One particular 73 was extremely vexing as one turn signal wire in the rear harness had perfect insulation but the copper wire had vaporized. Had to run a replacement wire from where the harness exited the cubby hole behind the seat all the way thru the rear quarter to the driver's side tail light. Getting access to the connector below the dimmer switch will let you rule out the turn signal and four way flasher switch output. You have to remove the sill plate and roll back the carpet on the driver's side to get in there. Brake lights go thru the turn signal before going to the rear. Hope this makes sense.
     
  6. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    11,351
    Location:
    Seguin, TX
    Yes there is, I dealt with my dimmer switch earlier this year, and even if there isn't a connector, the harness could have a stress point that breaks the wire without breaking through the insulation. That would be a good idea to pull the plate to inspect for damage. To check for if the switch is involved or not (although I think it isn't, as the 4-ways all work), the switch pigtail connector is a better place, as it allows backprobing, rather than piercing the insulation.
     
  7. Hillbilly

    Hillbilly In Maximum Overdrive

    Messages:
    6,030
    Location:
    Winchester, TN.
    Andy, when hunting why no juice at the back end, I always went to that connector first after seeing what the moisture did to the first one. That connector under the dimmer switch had all the wiring functions connected to the rear of the vehicle including all rear lighting and the fuel guage. As the forward part of the connector was the terminus of the dash harness, it was easy to probe while checking if the juice from the various switches actually made it to that point.
     
  8. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
    11,351
    Location:
    Seguin, TX
    Right, but I was only saying if there is no connector there. If there is, then yes, check there, it gives you the same checks without trying to access the turn signal connector.
     
  9. RANCHEROROB

    RANCHEROROB In Maximum Overdrive GOLD MEMBER

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    3,523
    Location:
    Pueblo de Los Angeles, Aztlan
    Bad turn signal switch
     
  10. plumcolr

    plumcolr In Maximum Overdrive SILVER MEMBER

    Messages:
    1,470
    Location:
    Freehold NJ
    Not familiar with a '74. But if the brake lights and the turn signals use the same bulb in the back, the fault is in the turn signal switch, per RANCHEROROB.
     
  11. Lowrider

    Lowrider In Third Gear

    Messages:
    190
    Location:
    Kingman AZ.
    X3
     
  12. tbird9140

    tbird9140 In First Gear

    Messages:
    23
    I guess my problem is in the turn signal switch and as I have ordered a new one which is supposed to show up on the 7th of January, I guess I will wait until I can install it to see if this cures my problem. I am reluctant to tear up the sill plate, seat and carpet, in order to expose any wiring and connector in the vicinity of the high/low beam switch, only to find out I have a bad turn signal switch. However, and maybe I am missing something, but I really don't understand how the switch will allow me to have brake lights on one side of the rear, but not the other. Normally I would have concluded that my problem had to be a bad wire or connection specific to the nonworking brake side. If any of you can give me an education on how the turn signal switch can allow brake lights on one side of the rear, but not the other, it would be appreciated. A belated Happy New Year to you all.
     
  13. Hillbilly

    Hillbilly In Maximum Overdrive

    Messages:
    6,030
    Location:
    Winchester, TN.
    The switch divides the power source , either from the brake light switch or from the turn signal flasher. There are fixed position contacts in the switch for each rear light. When you move the turn signal lever you also move a sliding contact plate. In the neutral( Middle Position ) of the lever, the contact plate connects both rear lamps to power from the brake light switch. In either the right or left turn lever position, the slider plate moves off of one of the rear light contacts while another slider plate connects one rear lamp to the turn signal flasher. Amazingly simple design save for the fact that the contacts eventually wear out or the plastic frame of the switch eventually distorts leaving no connection to the internal contacts. There is also another set of contacts and sliders that control the front lights and dash warning lights.
     
  14. tbird9140

    tbird9140 In First Gear

    Messages:
    23
    OK guys, back here for a report. Yes, my problem was in the turn signal switch. The new one is installed and I now have lights all around; running, turn signals and brake lights. Just for kicks, I ordered a replacement cam, and tore my old switch apart. Moving the springs and contact sliders over to the new cam gave me a much better understanding of the switch's operation. This visual and Hillybilly's excellent explanation of the internal workings of the switch have now turned me into a turn signal expert - NOT. Guess what, I now have no emergency hazard blinking lights! After completing the turn signal switch installation, I pulled out the hazard knob, and got nothing. Don't you just love working on old cars? Please don't tell me to replace the hazard blinker on the fuse box as this was the first thing I did. Tomorrow I plan to go into town and get another hazard blinker, hoping that my first replacement was defective. I guess that my problem could be in my newly installed turn signal switch, but I am not looking forward to tearing the steering wheel apart, again. Short of carrying some roadside flares, does anyone have any suggestions on how to cure my current Ranchero ailment? As always guys, thanks for your help and stay safe. Them vaccines is a cummin.
     
  15. Hillbilly

    Hillbilly In Maximum Overdrive

    Messages:
    6,030
    Location:
    Winchester, TN.
    I would first probe the connection that the hazard flasher plugs into just to make sure there is a constant 12 volts on one side. If you have juice go further and see if it goes thru the flasher unit all the way to the turn signal connector. I am sure that you are now familiar with that funky grease inside those switches. Years of not being moved can let that grease harden and turn into a very good insulating coating. Since that switch also has sliders and springs, you can visualize them not hitting the contacts because of that dried up grease. Try moving the switch button numerous times while giving the button a slight gentle twist as you cycle it. If no results, carefully drown the switch with electronics contact cleaner. The hard part is protecting the painted surfaces and the clear speedo lens from spatter. All those four way switches I have attempted to revive did resume working after a few soaks of contact cleaner. Good luck !
     
  16. tbird9140

    tbird9140 In First Gear

    Messages:
    23
    OK, I will probe the connection of the hazard flasher tomorrow to see if it has constant 12 volts on one side. I am confused a bit however on the ongoing steps you recommend. My turn signal switch is now new. Why would it have funky dried grease? When you suggest moving and twisting the switch button several times, I presume you mean the switch button that sticks out from the side of the steering column. If this doesn't work you suggest "carefully drown the switch with electronics contact cleaner". Do you mean removing the turn signal switch again from the column to do the drowning, or somehow try to drown it from outside the column while it is still in place? Thanks for the advice, sorry to be so slow minded.
     
  17. thebruins

    thebruins In Third Gear

    Messages:
    105
    When I installed my new turn signal switch a little while ago, the new unit came with a very long wire & plug. The old unit was connected to the car's wiring in the steering column; the new unit's wire was so long I could plug it into the car's wiring behind the dashboard giving me easy future access to the plug. Maybe that will work for you as well.
    I would not drown it yet, but as Hillbilly suggests, first test the flasher and then check if there is power coming through the turn signal switch's plug. It shouldn't be too hard to find a wiring diagram so you know which wires to probe.
     
  18. Hillbilly

    Hillbilly In Maximum Overdrive

    Messages:
    6,030
    Location:
    Winchester, TN.
    New doesn't necessarily correspond with being built in the last year, or even the last decade. You might be surprised how old some replacement parts really are and how long they were on a shelf in a warehouse. Yes, that little button for the four way flashers. Gently add twisting motion, remember that it is plastic parts you are messing with. Carefully drown means taking whatever steps needed to catch the excess spray on contact cleaner. Paper towels, old rags, whatever you have to catch the extra cleaner before it runs down the column onto the carpet, your shoes, etc. With the column still assembled spray the cleaner into the switch using the tiny gap around the button. Wear eye protection as the cleaner tends to go everywhere but where you want it to go.
     
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