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  • 3 alternators no charging

    1998 Contour: V6 automatic power everything

    Alt crapped out last month when ATF from transmission sprayed everywhere. Replaced trans, alt and PS pump belts and tensioners. First alt replaced (shop is doing the work under warranty) had bad bearings/windings. It was charging somewhat but not enough. Brand was Ultima (reman/new) from O'Reilly. Shop went through 2 others that appeared to test ok on the bench, but only put out 12 volts on the car.

    We also replaced the battery cables with slightly larger ones, better ground cables as well. However on the 4 power leads from the junction boxes were bundled together when they redid the wiring; and now the alt isn't charging. I find it odd that 3 alternators are not working in a series like this.

    What I am wondering is if the bundled wires feeding power to the junction boxes may be part of the problem where the amperage is dropping just enough to not send the signals to the alternator to excite the rectifier in the alt. Is it possible that there could be resistance in that harness somehow (I don't see any wiring damage to indicate that. Also, I only see the red wires, not the white with black tracer wire.

    Edit:

    Did find the problem. In the instrument cluster, there is a communication bus line from the PCM and that monitors what is going on with the powertrain, airbag system, charging system and ABS (if that is installed). On the charging system, the cluster sends data back to the PCM on status of the charge and if it does not see it, the computer will either send data to the alternator to ramp up the charge; or turn it off. What it was doing is ramping up the alternator to full field 100% of the time. That shorted out the alternators immediately. On the oem alt, it did not short it out because the VR was able to handle that.

  • #2
    Collectively we have seen this often with rebuilt alts - they just don't work once installed, and the bench testing method does not test it correctly. Have you tried a 100% new unit yet? THat is typically the fix - it was for me last fall.

    As for wires, that was a good step replacing the pos & neg large wires with new cables. If you are worried about resistance, get a volt meter and measure the wire resistance. Bundling or zip tie-ing them together shouldn't matter.
    2k SVTC - Black / Praire Tan, blu_fuz ported 3.0L, 58k motor, 118k chassis

    http://www.contour.org/ceg-vb/attach...chmentid=16333

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    • #3
      Originally posted by ScotSHO View Post
      Collectively we have seen this often with rebuilt alts - they just don't work once installed, and the bench testing method does not test it correctly. Have you tried a 100% new unit yet? THat is typically the fix - it was for me last fall.

      As for wires, that was a good step replacing the pos & neg large wires with new cables. If you are worried about resistance, get a volt meter and measure the wire resistance. Bundling or zip tie-ing them together shouldn't matter.
      I called the shop and they said all of them have been remans. However I want the shop to check out the wiring harness that goes from the junction block to the battery. Satya had said that harness goes bad easy.

      Last year I was lucky in getting a rebuilt unit that was able to charge well. The first one overcharged and the ecu turned the alt off at high rpm. The second one worked. This time, atf was spraying everywhere and destroyed The alt and when the trans was replaced the alt also was swapped out. It charged for maybe a week or 2 and it started grinding. 3 alts later, still no charge

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      • #4
        hi there.
        98 EO SVT Deleted Cat/Blue Chip in PCM/Foglight Mod/Moosing Fix BAT struts/spring Carbon Fiber Cowl Hood & Carbon Fiber Nascar Trunklid

        2000 Red/Tan SF connectors/ frontnrear strut braces, BAT struts/springs B&M shifter, Bosal Exhaust/ Dynomatted,

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        • #5
          I sold both rebuilt and new alts there for a while and fully 20% or so of them are bad right out of the boxes, it's a HUGE problem for the parts stores. 3 in row is a bit unusual but BTDT too. Much of the issue is that the builders absolutely refuse to use quality regulators, they'd much rather give that money to the CEO. The cheap Chinese regulators often fail in minutes, I rebuild my own alts and ALWAYS use much more expensive regs and it shows, they keep on working right.

          It's just not that hard to build an alt but the people doing it are not very smart, they commonly never even turn the pulleys to see if something might be dragging, that being one of the major problems and an idiot can catch that. Or maybe not eh? I saw fields shorted to cases and bad internal grounds on them all the time; they simply do not care and part of China's getting the upper hand on the USA in every way they can.

          Testing them is greatly problematic too, the quick connectors used on todays' alts work great but only for 2-3 times, once you start reconnecting them over and over in testing the test leads go bad quickly and most of the parts stores do not cycle them out for new like they should as after 5 times use they will be bad again and the stores get charged for that.

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          • #6
            Originally posted by amc49 View Post
            I sold both rebuilt and new alts there for a while and fully 20% or so of them are bad right out of the boxes, it's a HUGE problem for the parts stores. 3 in row is a bit unusual but BTDT too. Much of the issue is that the builders absolutely refuse to use quality regulators, they'd much rather give that money to the CEO. The cheap Chinese regulators often fail in minutes, I rebuild my own alts and ALWAYS use much more expensive regs and it shows, they keep on working right.

            It's just not that hard to build an alt but the people doing it are not very smart, they commonly never even turn the pulleys to see if something might be dragging, that being one of the major problems and an idiot can catch that. Or maybe not eh? I saw fields shorted to cases and bad internal grounds on them all the time; they simply do not care and part of China's getting the upper hand on the USA in every way they can.

            Testing them is greatly problematic too, the quick connectors used on todays' alts work great but only for 2-3 times, once you start reconnecting them over and over in testing the test leads go bad quickly and most of the parts stores do not cycle them out for new like they should as after 5 times use they will be bad again and the stores get charged for that.


            I am having the shop who is doing it (it is under their warranty) try one from a different brand thsn what they have been getting. The reason why they are doing it is they had to swap it out because atf from the transmission went everywhere and the connector to the VR cracked. Dell at the shop who is their electronic diagnostician went through the wiring several times and did pull the harness apart to see if that failed. He sent pictures to me and the wiring is intact and in good condition. The alternator they put in last month was working but it was also backfeeding in reverse (it would provide a charge but it would also pull power from the battery at certain rpms). It also was grinding loudly as well.They are going with a local rebuilder in getting a new one, if this one they ordered Saturday fails.

            My thinking is the car really is fussy on voltages and it wants to see a particular brand of regulator to work right. The local builder said he can load up the alternator full field and check the VR in the specific voltages the car produces.

            Comment


            • #7
              2k SVTC - Black / Praire Tan, blu_fuz ported 3.0L, 58k motor, 118k chassis

              http://www.contour.org/ceg-vb/attach...chmentid=16333

              Comment


              • #8

                I had a local rebuilder tell me (who has many years experience) that it is best to go with an OEM (new or reman) alternator. The VR has a sense circuit (the 98's have a constant power on one leg of the voltage regulator and the second leg is the sense circuit leg). The sense circuit according to his schematic goes through the cluster, which there is a communication circuit to the pcm where the pcm monitors the alternator that way. He also said that the voltage regulator is a specialty unit that needs to be designed one way to have the PCM communicate with it.

                I went with an OEM Motorcraft unit.

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                • #9
                  Found why the alternator blows itself up.

                  Inside the cluster is a circuit with a diode that is part of the charge sensing circuit that is blown. The faulty diode is making the PCM think the alternator is not charging which it tells the voltage regulator to ramp up the rate of charge.

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                  • #10
                    Interesting. That is the first time I've heard of that happening, good to know.

                    I see the diode on the wiring diagram, but it is truly just the regulator & diode not working right - no PCM interaction. What made the diode fail?

                    2k SVTC - Black / Praire Tan, blu_fuz ported 3.0L, 58k motor, 118k chassis

                    http://www.contour.org/ceg-vb/attach...chmentid=16333

                    Comment


                    • #11
                      Originally posted by ScotSHO View Post
                      Interesting. That is the first time I've heard of that happening, good to know.

                      I see the diode on the wiring diagram, but it is truly just the regulator & diode not working right - no PCM interaction. What made the diode fail?

                      The PCM does handle it in a back door method through the cluster. The wiring diagram there shows the charging system circuit, but what it doesnt show you is the interaction with the PCM. That is done through the cluster itself. Another diagram that has the cluster schematic does show the connection from the PCM to the sense circuit. Dell and Rob noticed it when they backprobed the wiring at the CJB, alternator, and cluster. They saw the low signal sense circuit at the CJB but also the same value at the cluster input, BUT did see at the output of the sense signal circuit at 100% as well as the 100% cycle at the alternator. The low signal was because the system wasn't seeing the high output of the sense signal from the alternator.

                      Retesting the voltage regulator with a adjustable sense tester did find the voltage regulator operated normally and they discovered a technical bulletin about it to replace the cluster if the voltage regulator is at constant full field is present or alternator shorting out quickly.

                      I don't know what made it short out. Josh thinks it has been like that for a while and through digging into it, found the bad diode. It is possible to replace the diode which they are attempting, but ordered one just in case if that did not work. The test tools they used were the lab scope, with multiple channel inputs and the high end scan tool to see the data from the cluster module.

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                      • #12
                        How the system works is at the cluster, the PCM monitors it through a back door smart system indirectly and IF the alternator is overcharging, the PCM is telling the cluster to turn off the alternator. Last year when I had a bad alternator replaced and got one that had a bad VR, when I revved the engine past a certain point, the alternator would automatically turn OFF. The threshold is anything past 16.4 volts the cluster cuts the sense circuit offline from the CJB. Below that, it will keep the circuit live and connected. The shop did the work last year and had never seen an alternator turn off if the rpm was higher. The alt light in that condition was bright when the voltage was over 15.5 but dim if the voltage is under 12 volts.

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                        • #13
                          WOW! Thanks, it is a tangled mess when you dig in!
                          2k SVTC - Black / Praire Tan, blu_fuz ported 3.0L, 58k motor, 118k chassis

                          http://www.contour.org/ceg-vb/attach...chmentid=16333

                          Comment


                          • #14
                            Originally posted by ScotSHO View Post
                            WOW! Thanks, it is a tangled mess when you dig in!
                            Tangled, yes, but now it is a protocol in testing these systems. We have to realize in modern cars built after 1986 that the PCM is involved in many things, and testing the operation involves more than a simple field test. It involves expensive equipment and tools. The lab scope is $10,000. Scanners are also about that same price that have the ability to access body control functions, and can tap into the controls by electronically switching off and on various control systems. With this equipment, I have the ability to activate injectors, IMRC, alternator duty cycles, A/C, electric power steering devices, cooling fan and a buttload of other tied in stuff.

                            I ran into a car with the same issue years ago on a 1986 Subaru. It would not communicate back to the PCM from the alternator, and the alternator would mysteriously turn itself off. In that case, the cluster was interfering with the system as well. Had to replace the cluster as well as a shorted wire unrelated to the charging system.

                            Comment


                            • #15
                              What we are going to do is replace the entire cluster assembly, because we found the backing of the circuit board separating from the hard board. Rob thinks not only the diode went bad, but also other parts of the circuit board is bad. That cluster too is tied into the transmission control module (and speed sensors) among other things. Might have been causing trouble with other systems and it is easier and cheaper to swap it out.

                              Once Josh sends me some pictures, I will post them.

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