68 merc montego wiring woes

Discussion in 'General Automotive Tech' started by Wagonrodder, Aug 26, 2021.

  1. Wagonrodder

    Wagonrodder Member

    Joined:
    Jul 9, 2021
    Messages:
    57
    Likes Received:
    14
    Trophy Points:
    20
    Wagon Garage:
    1
    Jeeze,wondering if I should call this post 2 steps forward and one step back, or its always something...we bought a beautiful 68 mercury montego about 7 weeks ago, I just completed the thread called 68 merc leaky gas tank where I documented removing and repairing the gas tank,then we got to enjoy driving the car 2 days before all hell broke loose..on day one the turn signals quit working yet the 4 way flashers still worked along with all the other lights...the car did have electrical problems when we got it but those things all worked, on day 2 while trying a new turn signal flasher that didnt work,and switching the lights off and on, ALL electricity on the car quit...by that I mean its like theres no battery in the car..nothing comes on, motor doesnt turn with key switched on, headlights dont come on, nothing works...the only good thing was i discovered i can start the car on "life support" by hotwiring it at the starter solonoid and at least move the car around,... so the ignition circuit still works but thats all,no power is getting to the headlights or key switch...nothing, to try to fix the problem so far i have tryed
    replacing the starter solonoid
    replacing the ignition switch
    removing and testing each fuse and cleaning the corrosion from the fuse block (no bad fuses)
    removing and cleaning the "main" ground where the negative battery cable goes to at the motor along with the large wire that grounds from the bundle that goes to the starter solonoid
    cleaned every other ground i can find and its still like theres no battery in the car...
    to me it seems like there must be a "main" fuseable link somewhere thats blown not letting any power go to inside the car but I cant find any mention of one in my manual...question, if something was bad in the alternator could that prevent power from getting to the headlight and ignition switch? i never noticed any charging problem with it but its old and might be my next part to replace but I hate going willy nilly changing parts and hoping for the best...somewhere theres a huge "open" and its frustrating! what ever it is it seemed to blow all at once and thats why im leaning twards a fuseable link but I cant find one...the odds with a car this old someone on this site knowing the problem are slight but I have to try...my plan "b" is to save up for the next 6 months with the car sitting and find a place to take it in for a complete modern rewire but man there must be a way to fix this since something suddenly blew...thanks in advance for any advice...my friend did tell me in 1968 his father bought a new montego 4 door sedan and it always had wiring problems from new until they sold the car and turn signals was one of the problems...so guess they had wanky wiring from the factory
    Screenshot_20210820-173608[2997].png
     
  2. HotRodRacer

    HotRodRacer Moderator Staff Member Moderator

    Joined:
    Oct 24, 2017
    Messages:
    706
    Likes Received:
    228
    Trophy Points:
    128
    What does the negative battery cable look like? Is it a "like stock" molded end cable, or a clamp-on terminal? If it's a clamp on I would take it apart, clean the cable and the inside of the clamp assembly, and put it back together to see if it solves the problem. My grandson's 92 F-150 had that issue and I like to have NEVER found it. Like you I cleaned all the ground points, cleaned the post and terminal, and still wouldn't do anything. It ended up being what I just described.

    Good luck.
     
  3. Wagonrodder

    Wagonrodder Member

    Joined:
    Jul 9, 2021
    Messages:
    57
    Likes Received:
    14
    Trophy Points:
    20
    Wagon Garage:
    1
    thank you for the great suggestion! ive had to do the very same thing on other vehicles ive owned but for some reason hadnt checked it on the wagon, i got excited for a short time as i did find corrosion at the wire and clamp but after making everything shine alas it wasnt the problem...i cant help thinking there must be a fuseable link somewhere but if there is it must be in the wiring thats wrapped somewhere because ive looked everywhere else...my next thing to try is remove the alt and clean the connections on the back as i can see its been on the car for some time and likely has corrosion like everything else on the car...hopefully i will find the issue someday thru the process of elimination?
     
  4. OldFox

    OldFox Curmudgeon

    Joined:
    Feb 20, 2013
    Messages:
    1,126
    Likes Received:
    216
    Trophy Points:
    135
    Location:
    West Tn
    Don't people use test lights anymore to trace down electrical problems?
     
  5. Wagonrodder

    Wagonrodder Member

    Joined:
    Jul 9, 2021
    Messages:
    57
    Likes Received:
    14
    Trophy Points:
    20
    Wagon Garage:
    1
    technically the process of elimination could include using a test light couldnt it?
     
  6. Silvertwinkiehobo

    Silvertwinkiehobo "Nothing is foolproof as fools are ingenious."

    Joined:
    Apr 21, 2014
    Messages:
    12,502
    Likes Received:
    2,105
    Trophy Points:
    560
    Location:
    Seguin, TX
    Yup! It's what I recommend. Unfortunately, I'm not at home in Texas, so I don't have access to my '68-'74 wiring diagram book. But if you have a fuse block, turn on the ignition, check the block for power, on BOTH terminals (not the fuse ends). If you have power there, then go to the flasher pigtail, unplug the relay, and check for power. If there is power there, take a jumper, and jump the terminals. Move the turn stalk one way or the other for a second, click on, click off; if the switch is good, each side will light up for that second. If not, look at the switch itself.
     
  7. elB

    elB Well-Known Member

    Joined:
    Dec 2, 2014
    Messages:
    1,116
    Likes Received:
    169
    Trophy Points:
    135
    Wagon Garage:
    3
    Location:
    NorCal
    Ford is known to have had wonky wiring problems in this era from the people I know who owned them. The most important thing to do is grab a wiring diagram from a factory service manual, it will show you the power feeds and where they run. In my experience there's either a wire with a bad crimp\connection between the starter solenoid battery post and the main power feed to the car or weird grounding problems due to age.

    There's nothing wrong with the process of elimination, but it is a frustrating experience to throw parts at it and get no better. You've tossed parts, now it's time to dig into the wiring harness and find out where the bad connection is.
     
  8. Wagonrodder

    Wagonrodder Member

    Joined:
    Jul 9, 2021
    Messages:
    57
    Likes Received:
    14
    Trophy Points:
    20
    Wagon Garage:
    1
    Thank you for the great advice everyone...and im going to follow it, i consider myself a pretty good mechanic but electrical has always been my weak subject, however i guess i know just enough to be dangerous hehe, since theres no power inside the car at the fuse block,headlight switch,or ignition I too feel its got to be a main power feed from the solenoid where i know theres power, plus the car can be hotwired there and run..., thats why i was wondering if there could be a fuseable link somewhere wrapped up in a bundle? i was told at one point the car was a show car and a previous owner did a most excellant job of concealing or wrapping most of the wiring so im just going to have to undo all that...can anyone tell me what the red box in the photo is correctly called? im thinking its an ignition module? it has 5 wires coming out of it that go in to a bundle that goes directly thru a hole in the firewall to inside the car (perhaps to the ignition switch?) not to the fuse block on the engine compartment side...i will find a wiring diagram, have test light in hand and see what I can do...thanks guys!
    20210829_142256[3011].jpg 20210829_142256[3011].jpg
     
  9. Silvertwinkiehobo

    Silvertwinkiehobo "Nothing is foolproof as fools are ingenious."

    Joined:
    Apr 21, 2014
    Messages:
    12,502
    Likes Received:
    2,105
    Trophy Points:
    560
    Location:
    Seguin, TX
    If I'm not mistaken, that is Ford's transistorized ignition module, an upgrade of point-condenser ignition. I know Ford had kits in the mid-70s for doing the conversion, including parts that replaced the points and condenser, but I think that, like Pontiac's transistor ignition, the factory install just used the point set as the trigger. If someone knows more about them than I do, please feel free to speak up
     
  10. Wagonrodder

    Wagonrodder Member

    Joined:
    Jul 9, 2021
    Messages:
    57
    Likes Received:
    14
    Trophy Points:
    20
    Wagon Garage:
    1
    Might have found the problem(or one of them) today but im not quite sure how to go about fixing it...today I unbolted the fuse block from between the engine side and the passenger side at the firewall,one of the main feed wires,(I think there are two),(the biggest diameter wires), (and this one runs from hot on the solenoid).... and the wire at the engine side goes inside the biggest male pin on the block, im assuming when new it was either crimped or soldered but now the wire is loose inside the pin, as i was checking the pin itself with my meter sometimes it had power,sometimes it didnt ,yet when i hooked the meter to the wire itself it always had power so the wire is loose inside the pin...so loose it feels like it will pull right out of the pin, problem is i dont think i can remove the male pin from the block itself to properly solder or crimp the wire back in, to establish a good connection again, has anyone ever dealt with something like this? in the old days of course a person would likely replace the part of the block and wiring on the engine side with a new one but pretty sure they have not been available for years...going to have to think about this, perhaps run a jumper wire around the block to the female part of the block inside the car? or try to carefully cut the pin out of the block to solder it then put it back in the block? any suggestions would be great.., it does concern me if this wire was loose if there are others...in between the male and female parts of the block everything was really pretty clean so i will clean them with contact cleaner for starters..relieved i found a problem but not sure if its the only one or how to fix it...wish i knew that unknown guy somewhere that has a NOS engine compartment side harness sitting in his parts stash somewhere hehe but now this is a job for Macgyver so im going to try to channel him i guess.
    P.S. elB you nailed it! you said a "bad crimp or connection" and you were right on! thank you!!
     
    Last edited: Sep 11, 2021
  11. Wagonrodder

    Wagonrodder Member

    Joined:
    Jul 9, 2021
    Messages:
    57
    Likes Received:
    14
    Trophy Points:
    20
    Wagon Garage:
    1
    So i have a plan now after thinking about it a while,if it works i hope it might help someone else with a similar problem someday...if you look at the picture the big pin in question is at the lower right hand corner, the wire is so loose in it that it slides back and forth,this is the main feed i believe, on the outside(wire side) of the block is a rubber boot, when new it would be able to slide back but mine is so old it firmly bonded to the wires and is frozen, im going to try to exacto knife cut it off the plastic block in a manner that i can possibly reuse it,if not i will silicone seal each wire on the reinstall, then i will remove the loose wire and try to push the pin out the back side,the same way it went in...then i will clean the wire and the inside of the pin,and both solder and crimp it to establish a positive connection again, then, if im "lucky" push the pin back in to the block and hope it will fit firmly back in to place enough that when i put the 2 halves of the fuse block back together that it wont "push back" rather than going inside its female counterpart on the other half of the block, if it trys to do that i will try to push it in with a tool to seat it in the other half, and if that doesnt work either i will drill the hole bigger in the pin location of the block and "pass" the wire and pin thru it and plug it in to its female counter part by hand as i plug the 2 halves together pulling out the wire slack as i go...while i was using my meter checking the pin, twice the motor turned over with out having to be hotwired at the solenoid, i think for a second the wire connected inside the pin and the meter lead touched another pin, scared me but no fingers were in the way and i took it as a good sign this was the problem since there was no power getting to the ignition switch before..in a way i feel like im playing with fire trying to take the block pin out risking making the block fubar but desperate times call for desperate measures when you cant buy a new one...im also going to use my little dremel tool to clean all the other pins and contact clean everything before reassembly...will update with the outcome, and before i start i will wait to see if anyone else has a better way? thanks for reading!
    20210911_160000[3021].jpg
     
  12. Silvertwinkiehobo

    Silvertwinkiehobo "Nothing is foolproof as fools are ingenious."

    Joined:
    Apr 21, 2014
    Messages:
    12,502
    Likes Received:
    2,105
    Trophy Points:
    560
    Location:
    Seguin, TX
    Do not use silicone or RTV, they have corrosive ingredients. Give your wife's craft implements a raid for a hot glue gun. The glue ingredients are inert as well as non-conductive. But, that design of connector, IIRC, is the first design of connector with removable terminals. That white piece is clipped in; it prevents the tabs that lock the terminals from breaking or bending, allowing the pin to fall out. I'm not 100% sure on this, so be very, very careful on how you proceed. Also, one thing you can do to foster better connections, is to take a small pick tool, and use it to make the female terminals on the other side of that connector tighter. They expand and contract, but I've found they expand more than contract, and degrade the connections over time.
     
  13. Wagonrodder

    Wagonrodder Member

    Joined:
    Jul 9, 2021
    Messages:
    57
    Likes Received:
    14
    Trophy Points:
    20
    Wagon Garage:
    1
    Silvertwinkiehobo thats great advice! thank you! im going to try and get that white tab figured out so i can pop out that pin..the wire is a solid core that looks to be about 10 guage, i will try to make the female side a bit smaller as well and you are correct,the wife does have a hot glue gun hehe...can we get a hint about your secret project?
     
  14. Wagonrodder

    Wagonrodder Member

    Joined:
    Jul 9, 2021
    Messages:
    57
    Likes Received:
    14
    Trophy Points:
    20
    Wagon Garage:
    1
    WOO HOO its fixed!! and i hope my stumbling thru this issue may help someone else someday...first of all much credit goes to Silvertwinkehobo for his excellant advice! thanks Bud!!, and Elb, everything works now,even the gas gauge that didnt work before, i could tell as i tightened the fuse block back together and the interior lights came on before i was done that it was fixed, the car now starts with the key again and has lights turn signals and everything....it wasnt easy, it involved removing a pin from the fuse block, cleaning the wire (it was the main power feed to the interior) soldering it in to the pin and putting the pin back in the fuse block...the pin was only crimped,not soldered from the factory..when i first pulled the wire out of the pin i thought the wire had melted but there was no evidence of heat damage, a closer examination revealed the "green" you see at the end of the wire was nothing but corrosion that likely started in 1968..., its the black wire with the yellow stripe, as it got worse over the years things stopped working one at a time, if you have a ford product of this era and have electrical issues this is something to look at! thanks everyone that read this post!...time to go rolling!
    20210912_154627_HDR[3035].jpg
     
    Last edited: Sep 17, 2021
  15. elB

    elB Well-Known Member

    Joined:
    Dec 2, 2014
    Messages:
    1,116
    Likes Received:
    169
    Trophy Points:
    135
    Wagon Garage:
    3
    Location:
    NorCal
    Time to put some miles on it!

    Now you see why most shops refuse to do anything for electrical problems besides "throw parts at it and hope it goes away."
     

Share This Page