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A couple of electrical issues.

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  • A couple of electrical issues.

    My car has been in a local custom shop for about 2-1/2 years. Making this long story short I picked it up today and discovered that the brake lights, interior lights and digital clock display don't work. My first thought was a fuse but they all checked good. I have voltage through the brake switch and that's as far as I've gotten today. I've studied the electrical manual and cannot find a common denominator. I was beginning to wonder if a mouse had chewed into one of my harnesses.

    Anyway, I was hoping that maybe someone has experienced something like this and could quickly point me in the right direction. Otherwise it's troubleshooting the old fashioned way!

    Thanks,

    Dave
    Original owner --- 1978 Dodge Magnum XE


  • #2
    Did you check the fuse electrically or visually???

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    • #3
      Originally posted by dodgeboy8 View Post
      Did you check the fuse electrically or visually???
      I second that... good ground is most important as well..
      9-1-1 or 1911 Your Choice. Choose Wisely

      Member USCCA

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      • #4
        Originally posted by dodgeboy8 View Post
        Did you check the fuse electrically or visually???
        I checked the fuses with a meter. I measured the voltage at the brake switch with a meter. According to the electrical manual, the brake lights are fed with 12v to illuminate. The interior lights are illuminated with a ground. The clock is illuminated with a 12v signal on one of the inputs. I cannot find a common denominator as you would see with a blown fuse. Cigar lighter works, that shares the same fuse with the brakes.

        A bad ground for the brake lights would also affect the tail lights as the filaments share the same ground connection. The tail lights work fine.

        I was hoping that there was something simple that links the 3 things together that I've missed. Otherwise I'll have to troubleshoot these things individually. Just hoping to save some time.

        Thanks,

        Dave

        Original owner --- 1978 Dodge Magnum XE

        Comment


        • #5
          check for power at the dome light your right door switch grounds the light to come on.

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          • #6
            Here is what I found....

            Originally posted by dodgeboy8 View Post
            Did you check the fuse electrically or visually???
            I studied the electrical manual and put together a list of things to check. I was suspecting a damaged harness somewhere on the way back from the instrument panel to the trunk. After finding no issues I checked the voltage to the brake lights at the socket and found there was voltage. All four of the brake light filaments were open. I took a look at the interior lamps and found all four of those to have open filaments along with the map light. The bulbs had that black and silver haze on the inside which usually means the lamp filaments died a violent death. Went on to the clock and verified all voltages were present. I'm figuring the clock died the same death.

            On a hunch I checked the charging system and read 17.9 volts, way too high. I replaced the voltage regulator and that brought the charging system voltage back to just over 14 volts. Along with all of this mess the ballast resistor had been replaced before I brought the car back home.

            My guess is that the garage may have had a battery booster that was capable of 24 volts and someone had used it on my car. It would explain the damage to the filaments on the interior lamps and brake lamps. It's a wonder not more damage was done to the car's electrical system.

            Once I get the new lamps and clock installed I should be back in business.

            Thanks for all the comments.

            Dave
            Original owner --- 1978 Dodge Magnum XE

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            • #7
              Let us know

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              • #8
                Can't understand why someone would go with that much boost to start up a car. I would ask for sure or at least take a little trip to the place and look around to see if you can spot a booster like that. If they say no they didn't, I'd ask why would they even have such a tool in their shop and mention that your car shows the evidence otherwise. I have a charger/starting booster but it doesn't kick out high voltage.....

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                • #9
                  maybe they got one like this.
                  http://www.amazon.ca/Schumacher-PSW-.../dp/B002YK9ZYQ

                  Comment


                  • #10
                    Originally posted by Cranky View Post
                    Can't understand why someone would go with that much boost to start up a car. I would ask for sure or at least take a little trip to the place and look around to see if you can spot a booster like that. If they say no they didn't, I'd ask why would they even have such a tool in their shop and mention that your car shows the evidence otherwise. I have a charger/starting booster but it doesn't kick out high voltage.....
                    I would tend to agree. In addition to a restoration shop they also do everyday mechanic work, including some diesels.

                    I'm going over today to pick up some other things. I'll ask about their booster/charger. My thinking is that if they have one of those chargers that maybe whoever used it that time didn't pay attention to what they were doing. I honestly can't figure out what else would burn out that many lamps, the clock and the voltage regulator. Normally I have to keep a maintenance charger on the battery because if the car sits for 2 weeks without being started the battery goes through a discharge. You can hear it when the engine turns over. I think it's the radio and the clock causing the discharge. I'm sure the car sat over there for much longer periods than 2 or 3 weeks without being started.

                    I took the clock apart and found 2 burnt components. One is a resistor (12 volt input) and the other is an inductor (12 volt run input). It's old school discrete components, if the chip isn't toast I should be able to fix it.

                    I've ordered all of the parts including a replacement clock, probably be another 2 or 3 weeks before I get everything and get a chance to finish this up. I'll be sure to post (hopefully) a final update.
                    Original owner --- 1978 Dodge Magnum XE

                    Comment


                    • #11
                      Originally posted by daveo50 View Post
                      I studied the electrical manual and put together a list of things to check. I was suspecting a damaged harness somewhere on the way back from the instrument panel to the trunk. After finding no issues I checked the voltage to the brake lights at the socket and found there was voltage. All four of the brake light filaments were open. I took a look at the interior lamps and found all four of those to have open filaments along with the map light. The bulbs had that black and silver haze on the inside which usually means the lamp filaments died a violent death. Went on to the clock and verified all voltages were present. I'm figuring the clock died the same death.

                      On a hunch I checked the charging system and read 17.9 volts, way too high. I replaced the voltage regulator and that brought the charging system voltage back to just over 14 volts. Along with all of this mess the ballast resistor had been replaced before I brought the car back home.

                      My guess is that the garage may have had a battery booster that was capable of 24 volts and someone had used it on my car. It would explain the damage to the filaments on the interior lamps and brake lamps. It's a wonder not more damage was done to the car's electrical system.

                      Once I get the new lamps and clock installed I should be back in business.

                      Thanks for all the comments.

                      Dave
                      If the voltage regulator went bad wouldn't that blow the bulbs?
                      If so I don't know why one would think the shop had a 24V jump box.

                      I had a bike with a Generator (yea not a misprint)... I was constantly blowing bulbs, turns out the generator was stuck and it had some serious voltage coming out of it... cant remember what that voltage was, but it was the reason I kept blowing bulbs.
                      His car wasn't that fast, I caught him on the return road and passed him in the pits.
                      2006 Dodge 2500 CTD


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                      • #12
                        Originally posted by Trannyman View Post
                        If the voltage regulator went bad wouldn't that blow the bulbs?
                        If so I don't know why one would think the shop had a 24V jump box.

                        I had a bike with a Generator (yea not a misprint)... I was constantly blowing bulbs, turns out the generator was stuck and it had some serious voltage coming out of it... cant remember what that voltage was, but it was the reason I kept blowing bulbs.

                        You may be right. I checked with the shop today and they said the booster pack they use does not have 24 volt capability. The burned out bulbs were all flashed inside. The lamp for the map light was so black you couldn't even see the filament. I wonder why the front lamps didn't blow when I had been trying the turn signals? Anyway maybe it was as simple as that. I don't know if I have ever seen an electronic regulator fail in this state.

                        When I was trying to figure out how this happened the thought I had was; doors open, foot on the brake pedal and starting the engine. I've heard that you can damage voltage regulators when hooking up booster cables, I've just never seen that happen.
                        Original owner --- 1978 Dodge Magnum XE

                        Comment


                        • #13
                          too late now, but I guess the real test could have been to install a new bulb while it was charging the 17.9 volts, If that burnt the bulbs then you would have known.

                          maybe the reason the turn signal bulbs didn't blow is because of the short time the voltage gets sent to them.
                          His car wasn't that fast, I caught him on the return road and passed him in the pits.
                          2006 Dodge 2500 CTD


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                          • #14
                            Some years back the voltage reg went out on my 77 Dodge pickup and it blew the fuse on my radar detector but not the lights. The fuse on the RD was made to blow at 17 volts but the alternator didn't put out enough to blow any lights but it sure was nice having really bright head lights that night lol. Maybe using the headlights is what kept the other lights from burning out? At idle, everything looked normal but stepping on the gas made everything really bright.

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                            • #15
                              Originally posted by dodgeboy8 View Post
                              Let us know
                              I had some time today and here is the list.

                              4 Brake Light Bulbs
                              4 Interior Lamps
                              1 Map Light Lamp
                              1 Voltage Regulator
                              1 Clock

                              I bought the clock off of ebay and the one I got had the connector cut off. So, I had to transfer the connector from my original clock to the replacement. It seems nothing is ever easy. I wish the guy would have shown that in his pictures or description.

                              All of that stuff is now working correctly. Charging system is right at about 14.2 volts, so I think I'm in business as far as all of that goes.

                              Here is another list

                              Radio has one channel just about out and it's distorted. It was a nice Pioneer Supertuner I bought back in the early 80s and it worked great. I'm debating on putting the stock radio and speaker back in the car or installing one of those Mopar radios that play CDs and tapes. I bought one of those about 10 years ago and liked the CD capability. Now with those FM transmitters with memory cards that plugs into your cigarette lighter I don't know if you need to play tapes and CDs any more.

                              It looks like I have a couple of instrument lamps out too. I noticed a dark spot about the tach and speedometer.

                              It's all for another day.......
                              Original owner --- 1978 Dodge Magnum XE

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