1983 Coupe Deville electrical a/o fuel supply problems
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  • 2 Post By Slow and docile
RWD 19xx-1984 DeVille and Fleetwood,
1985-1996 Fleetwood and Brougham Forum Discussion, 1983 Coupe Deville electrical a/o fuel supply problems in Past Cadillac Vehicle Discussion; Hello. I'm quite new here. I decided to open a new thread because after lots of searching and googling I ...
  1. #1
    Slow and docile is offline Cadillac Owners Member
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    Exclamation 1983 Coupe Deville electrical a/o fuel supply problems

    Hello. I'm quite new here.

    I decided to open a new thread because after lots of searching and googling I couldn't find a solution for my problem.

    I got from a relative an old 1983 Coupe DeVille for small repairs with an electrical problem, especially the headlights wouldn't work properly.

    I quickly diagnosed a faulty headlight switch (left side under the wiper switch) and i noticed a "crispy" burnt white wire that went all the way from the switch connector to the door switch. I replaced the wire and the dome light and door lights started to work properly, after that with the use of a multimeter and a detailed 1984 Seville wiring diagram, I identified the wires: hot at all times, instrument panel lights, and the wire that is going to the hi/low beam switch in the steering column.

    Sadly i don't have acces to an genuine light switch for the caddy here in Poland, so I managed to adapt an skoda switch to work.

    Sadly after i fixed the light issue the car wont start... The starter is turning the engine, there is spark available but the darn fuel pump seems not to pump. I checked all fuses and relays without any effect. I am loosing my nerves and got few gray hair already.

    All help is very welcome and appreciated. Besides is there a way to access the ignition switch wiring in the steering column?

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  3. #2
    j2rossit is offline Cadillac Owners Enthusiast
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    Re: 1983 Coupe Deville electrical a/o fuel supply problems

    You need to check the voltage level leading to the pump (there is a connector at the back of the car).

    Can you hear the pump turn on for a few seconds when you first turn the key to run?

  4. #3
    csbuckn is offline Cadillac Owners Master
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    Re: 1983 Coupe Deville electrical a/o fuel supply problems

    Sounds like you're heading in the right direction. If you hear the pump turn on, I'd put a gauge on the fuel rail and see what you have for pressure.

  5. #4
    Slow and docile is offline Cadillac Owners Member
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    Re: 1983 Coupe Deville electrical a/o fuel supply problems

    Thanks for your fast replies.

    The Voltage going to the fuel pump was barely reaching 7 Volts.

    After that i was searching for other unusual voltage drops.

    I managed to get the engine running again.

    You would not believe what was causing all this problems.

    There was an "powder" fire extinguisher used to extinguish the small wire fire. The powder got into that giant square connector and humidity condensed on it causing all connectors to oxidize thus loosing their conductive properties.

    After cleaning it first with water in a spray bottle - the extinguisher powder is water soluble, then i sanded the gunk and sprayed them suckers with plenty of contact spray, to remove any traces of leftover water.

    I will try to start it again tomorrow and see if the effect is permanent or if, the process needs to be redone. In the meantime, I fixed them fiber optical wires so that they light up on the hood when each light is toggled.

    P.S what evil man put the fuse and relay boxes under the dash in this spinebreaking position...

    I will post you with the progress. The ye 'ol boat still has many faults f. e the cooler button on the CC won't work, the if in auto mode it randomly resets itself and so on.

    Take care and have a nice day/evening
    talismandave and talismandave like this.

  6. #5
    j2rossit is offline Cadillac Owners Enthusiast
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    Re: 1983 Coupe Deville electrical a/o fuel supply problems

    Yeah, they used to make Halon Fire extinguishers that used a gas to react with the oxygen and it didn't leave any powder or residue that needed to be cleaned up. But environmental restrictions put a stop to that.

  7. #6
    carnut is offline Cadillac Owners Master
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    Re: 1983 Coupe Deville electrical a/o fuel supply problems

    I would coat the metal connections with dielectric grease as well. This grease is a moisture barrier. Any time I disconnect a plug on this old of a car, I add dielectric grease before I plug it back together. I use it on spark plug wire boots as well. Makes it very easy to remove a wire from the spark plug.

  8. #7
    Slow and docile is offline Cadillac Owners Member
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    Re: 1983 Coupe Deville electrical a/o fuel supply problems

    Update, I fired up that beast today, engine runs perfectly, but sadly headlights will not work. Only working lights that are working are the tail lights, interior lights and position lights front, no low and high beam. I bet my money that the firewall connector has a loose contact, broken wire, or something. I will disassemble it and check it tomorrow.

  9. #8
    csbuckn is offline Cadillac Owners Master
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    The bulk connector almost under the brake booster will have all the headlight wiring. Check it out. The ground wire for the lights is up by the headlights.

  10. #9
    Slow and docile is offline Cadillac Owners Member
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    Re: 1983 Coupe Deville electrical a/o fuel supply problems

    Thanks for the fast reply, I figured it out to be this way. I still can't get over the fact that the fusebox is in this awkward position, and that the only protection for the whole headlights is a fusible wire (that burns trough at 10 million Amp's ) near the starter motor. The 80's were some weird times.

  11. #10
    j2rossit is offline Cadillac Owners Enthusiast
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    Re: 1983 Coupe Deville electrical a/o fuel supply problems

    I was going to suggest looking at the fusible link...
    Did you get them working?

  12. #11
    Slow and docile is offline Cadillac Owners Member
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    Re: 1983 Coupe Deville electrical a/o fuel supply problems

    Finally the engine and lights are both running, it did cost me a whole sheet of fine sand paper, a big bottle of contact spray, and an home depot electric connector for few cents, and obtaining an "genuine GM OEM" tool for testing the wiring called 10 ft of wire with an 10 Amp fuse

    The engine refused to start today again because the darn extinguisher powder residue was still corroding the connections between the fuses and relays. I cleaned them again, sanded them and generously sprayed them with contact spray to prevent it from happening again.

    Then with the help of the 10 ft wire, I was searching for the loose contact for the lights, and found it. It was a connector for 3 wires between the hi/low beam switch in the steering column and the fuse box. Why was there this connector anyways? I removed it and put there a new one and it works as new.

    Only problems left with this car are the windscreen washing fluid indicator which is still being lit, and the chimes do not come on, but they were annoying as hell so, I don't miss them.

    I will keep you updated with the progress.

    Thanks for all replies and have a nice weekend.

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