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    #1

    Alternator light on - where to start?

    The boat is running, sorta. Still can't idle consistently and has a leaky bowl transfer tubes, anyway

    The alternator light is steadily on. There's at least some charging going on, as when I let the engine almost die, the lights dim, and they get brighter as I rev up again. The smaller of the two positive wires (orange and black, going to the voltage regulator) has some cracking around the boot but no broken stands I can see. Otherwise the wiring seems good. As I try to clean up the wiring after all the changes (none to the alternator/regulator wiring) I have put the wire from the alternator to the starter solenoid post directly on the battery terminal. Could this change anything? Anywhere else I should look at? I do have access to a good voltmeter, test light, etc. but getting a consistent idle RPM is going to be difficult now. Also, voltage regulator (external) is 3 years/5K old.

    85 4 door 351 Civi Crown Victoria - Summer daily driver, sleeper in the making, and wildly inappropriate autocross machine
    160KMs 600cfm holley, shorty headers, 2.5" catted exhaust, 255/295 tires, cop shocks, cop swaybars, underdrive pulley, 2.73L gears.
    waiting for install: 3.27's, Poly bushings, boxed rear arms, 2500 stall converter, ported e7's, etc

    06 Mazda 3 hatch 2.3L 5AT (winter beater that cost more than my summer car)
    Tags: None
    #2
    I'm no expert here but I'd replace the battery cables, clean up all connnections and then replace the alternator and see what happens. I know when I replaced the battery cables in my 85 things got a lot better, cold cranking and charging. The cheap route would be to replace the cables, clean up the connections and then try to get the thing to idle steadily and measure voltage at the battery. I usually see 14.4 or better with my cars.

    Hope that helps.
    1985 LTD Crown Victoria - SOLD
    1988 Town Car Signature - Current Party Barge

    Comment

      #3
      The positive and negative cables and battery are clean and <3 years old. I should doublecheck the cable from the alternator to positive but didn't see anything obvious

      85 4 door 351 Civi Crown Victoria - Summer daily driver, sleeper in the making, and wildly inappropriate autocross machine
      160KMs 600cfm holley, shorty headers, 2.5" catted exhaust, 255/295 tires, cop shocks, cop swaybars, underdrive pulley, 2.73L gears.
      waiting for install: 3.27's, Poly bushings, boxed rear arms, 2500 stall converter, ported e7's, etc

      06 Mazda 3 hatch 2.3L 5AT (winter beater that cost more than my summer car)

      Comment

        #4
        Regulator sense wire goes to the battery too?

        Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
        rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)

        Originally posted by gadget73
        ... and it should all work like magic and unicorns and stuff.

        Originally posted by dmccaig
        Overhead, some poor bastards are flying in airplanes.

        Comment

          #5
          What kind of alternator? But put a voltmeter on it and see what it is putting out. Could be a bad diode in the alternator, might be a fubar regulator. Or a dirty connection where the light is triggered.

          Comment

            #6
            Have you ever had the alternator tested? A bad one is the big reason the light comes on, but bad connections between the alternator and the regulator will do it too. Make sure you're working with good parts first and go from there.
            86 Lincoln Town Car (Galactica).
            5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

            91 Lincoln Mark VII LSC grandpa spec white and cranberry

            1984 Lincoln Continental TurboDiesel - rolls coal

            Originally posted by phayzer5
            I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

            Comment

              #7
              This appears to be the basic 60 amp externally regulated. Where is my sense wire? My diagrams have routing but minimal explanation/naming. Never had it tested. I would be pulling it to test at a parts store since this thing barely idle right now. Are there any fuses to check?

              85 4 door 351 Civi Crown Victoria - Summer daily driver, sleeper in the making, and wildly inappropriate autocross machine
              160KMs 600cfm holley, shorty headers, 2.5" catted exhaust, 255/295 tires, cop shocks, cop swaybars, underdrive pulley, 2.73L gears.
              waiting for install: 3.27's, Poly bushings, boxed rear arms, 2500 stall converter, ported e7's, etc

              06 Mazda 3 hatch 2.3L 5AT (winter beater that cost more than my summer car)

              Comment

                #8
                the external regulator should have the sense wire. On a 3G, it's the yellow wire that goes to the battery or solenoid lug to sense what the charge cable is putting out.

                Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
                rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)

                Originally posted by gadget73
                ... and it should all work like magic and unicorns and stuff.

                Originally posted by dmccaig
                Overhead, some poor bastards are flying in airplanes.

                Comment

                  #9
                  How tight are the push-on connections on the back of the alternator?
                  If the female part widens out, they'll be loose and more vulnerable to corrosion. I'll look for a diagram but I'm pretty sure both of those should show a strong battery voltage with the key on.

                  Putting your charge wire on the + battery post is fine, as long as you keep the fuse link.
                  Pete ::::>>> resident LED addict and CFI defector LED bulb replacements
                  'LTD HPP' 85 Vic (my rusty baby) '06 Honda Reflex 250cc 'Baileys' 91 Vic (faded cream puff) ClifFord 'ODB' 88 P72 (SOLD) '77 LTDII (RIP)
                  sigpic
                  85HPP's most noteworthy mods: CFI to SEFI conversion w/HO upperstuff headers & flowmasters P71 airbox Towncar seats LED dash light-show center console w/5 gauge package LED 3rd brake light 3G alternator mini starter washer/coolant bottle upgrade Towncar power trunk pull underhood fuse/relay box 16" HPP wheels - police swaybars w/poly rubbers - budget Alpine driven 10 speaker stereo

                  Comment

                    #10
                    Hmmm... now I'm not sure what those wires should show...

                    The charge indicator wire comes right into the regulator, and the sense wire looks like it ties into the charge wire at the solenoid.
                    I guess 'S' is for stator and 'F' is the field switch here.

                    I hope the diagram helps at least, lol
                    Attached Files
                    Pete ::::>>> resident LED addict and CFI defector LED bulb replacements
                    'LTD HPP' 85 Vic (my rusty baby) '06 Honda Reflex 250cc 'Baileys' 91 Vic (faded cream puff) ClifFord 'ODB' 88 P72 (SOLD) '77 LTDII (RIP)
                    sigpic
                    85HPP's most noteworthy mods: CFI to SEFI conversion w/HO upperstuff headers & flowmasters P71 airbox Towncar seats LED dash light-show center console w/5 gauge package LED 3rd brake light 3G alternator mini starter washer/coolant bottle upgrade Towncar power trunk pull underhood fuse/relay box 16" HPP wheels - police swaybars w/poly rubbers - budget Alpine driven 10 speaker stereo

                    Comment

                      #11
                      yep, Field, Stator, Idiot (light) and whatever the other one is marked. They used to mark it as B for Battery. Connections between regulator and alternator must be good. The connection from alternator to battery needs to be good as well. I don't think it comes on if you lose battery sense, but you will get 18 volts of output if that happens. If your headlights aren't trying to burn holes through the pavement, you didn't lose the battery sense connection. If you can make a test light come on from ground to the large stud on the back of the alternator with the engine not running, that fuse link is good. All that remains at that point are the 2 skinny wires on the plug, and the alternator itself.
                      86 Lincoln Town Car (Galactica).
                      5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                      91 Lincoln Mark VII LSC grandpa spec white and cranberry

                      1984 Lincoln Continental TurboDiesel - rolls coal

                      Originally posted by phayzer5
                      I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                      Comment

                        #12
                        Thanks, that all helps a lot.

                        I love when it says "for 5.8L police". It's pretty much 50-50 whether that means my non-police 5.8 has it.

                        So battery sense is good if I'm not getting some crazy high number, and if I'm confident in the connections and everything testlights good it's time to look at the alternator.

                        85 4 door 351 Civi Crown Victoria - Summer daily driver, sleeper in the making, and wildly inappropriate autocross machine
                        160KMs 600cfm holley, shorty headers, 2.5" catted exhaust, 255/295 tires, cop shocks, cop swaybars, underdrive pulley, 2.73L gears.
                        waiting for install: 3.27's, Poly bushings, boxed rear arms, 2500 stall converter, ported e7's, etc

                        06 Mazda 3 hatch 2.3L 5AT (winter beater that cost more than my summer car)

                        Comment

                          #13
                          Checked connections at battery and voltage at battery, 13.9-14.1 volts steady at idle. Light still on. At this point I'm assuming it's just an issue with the wiring to the dash light

                          85 4 door 351 Civi Crown Victoria - Summer daily driver, sleeper in the making, and wildly inappropriate autocross machine
                          160KMs 600cfm holley, shorty headers, 2.5" catted exhaust, 255/295 tires, cop shocks, cop swaybars, underdrive pulley, 2.73L gears.
                          waiting for install: 3.27's, Poly bushings, boxed rear arms, 2500 stall converter, ported e7's, etc

                          06 Mazda 3 hatch 2.3L 5AT (winter beater that cost more than my summer car)

                          Comment

                            #14
                            unplug the voltage regulator and see if the light stays on. If it does, you've got something funny going on. Also, if you have changed that to an LED it might light where a normal bulb would not.
                            86 Lincoln Town Car (Galactica).
                            5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                            91 Lincoln Mark VII LSC grandpa spec white and cranberry

                            1984 Lincoln Continental TurboDiesel - rolls coal

                            Originally posted by phayzer5
                            I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                            Comment

                              #15
                              Will do. The cluster is totally OEM

                              85 4 door 351 Civi Crown Victoria - Summer daily driver, sleeper in the making, and wildly inappropriate autocross machine
                              160KMs 600cfm holley, shorty headers, 2.5" catted exhaust, 255/295 tires, cop shocks, cop swaybars, underdrive pulley, 2.73L gears.
                              waiting for install: 3.27's, Poly bushings, boxed rear arms, 2500 stall converter, ported e7's, etc

                              06 Mazda 3 hatch 2.3L 5AT (winter beater that cost more than my summer car)

                              Comment

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