Leaderboard

Ok I know several members have done this mod and said it was easy. It sure is easy. It takes about 2 hours from start to finish to complete this project. You'll need the terminal lugs and the metric bolt that @W-T specifies in his article. First thing disconnect your batteries. I unhooked the two negative leads. You need to gain access to the loom going across the front of the engine. So you'll need to remove the upper alternator bracket and the the two loom holders on the front of the block. I did this during my coolant flush project so my upper hose and thermostat are removed. If you have my crankcase vent that will need to be removed as well. Now I started at the battery and the alternator and started unhooking the wiring from these devices bring it forward. Now you start working on getting the split loom off the wiring. Start at the tape with a small exacto knife or razor blade and carefully split the tape to release the plastic split loom cover. Carefully remove it. I found out mine was brittle after all the years of engine heat. Once you remove all that slpit loom you can again split the spiral tape holding the loom together. Now you show be able to have both the ground lead and the alternator charge lead loose now. I will admit the alternator lead took a bit of work to release at the knot of tape on mine where it breaks out of the loom heading for the PDC. Just take your time with your razor blade and your get it released. You can clearly see the splice of the ground just like @W-T mentions in his article. Once you get the alternator lead out in one piece. Then the ground lead I used a pair of wire dikes and cut the ground right at the end of the splice. Now the alternator lead I reused the wire since it was in excellent condition. I mocked up the alternator lead by hooking it back up to the alternator like it should be and gave it a nice loop of slack then cut it to meet the positive battery terminal. On my terminal lugs, I took a hacksaw and scored the plastic collars and peeled them off for soldering. Then slipped the lug on and used a propane torch with the low flame and soldered the lugs right on to the wire. Good sold weld and this will seal the wire from future rot from battery acid and vapors. This is the completed alternator connection now. All I did was grab an old nut and stacked on the battery terminal. Now we are going to do the ground side. Now trim back the old splice and free the ends of the wires. Now strip back the wire so you can fit the wires into a lug. Again I did the same thing I took the hacksaw scored the plastic collar and peeled it off the lug and then slipped it on the wires and prepped it for soldering. Again just slipped the lug on the wires and low flame with a propane torch I soldered the lug to the wires. Now I cut the old plug off the splice on the passenger side ground and then trimmed the length of the wire with the plug so it would reach between the driver side battery and the gear case. Same again I peeled the plastic collar and slipped the lugs on and soldered with low flame propane torch. This gives you an idea where the wires go. Take your metric bolt and attach the ground wires to the case. Then the ground cable to the negative battery terminal on the driver side. Beyond this is just clean up. Now you need to tape up your loom again. I'm going to replace my split loom with a smaller size being the old loom was brittle and was breaking during removal. The only thing that should run across the front of the engine now should be the ECT sensor which is a twisted pair. The A/C compressor, A/C high-pressure switch, and the alternator field lead. Before AC noise level was 0.038 AC volts now after the mod its dropped to 0.015 AC volts (or 15mV AC). About the parallel cables... There is lot of folks being told they NEED the parallel the positive and negative cables. To test if you need that or not. Take a good quality DVM meter capable of DC mV scale. Now place a Black probe on the battery terminal and the red probe on the block (clean metal). Typically I see 3mV (0.003 volts) after doing the other part of the ground wire mod. Now take a set of jumper cables and go from the negative post to negative post. Also check the AC noise voltage with the jumper cable hooked up if there is no real change then you do not require the parallel cables. If the voltage drop is the same with the jump cables then you do not require the parallel cables because there are ZERO improvements. You can do this on the positive side as well. If there is a voltage change my first thought is to replace the BAD cables first before paralleling on a bad cable. All you do is covering up a bad connection. Adding the extra cables will not improve anything if it's not changing the voltage drop from point to point. Addon: Protection fuse or fusible link Some members are suggesting to install a fusible link or fuse of the same size at 140 Amps on the charge lead as a protection method. Just in case for some reason the diode bridge happens to short the positive side to the ground and doesn't start an engine fire. As for the size of the fusible link is still unknown as of yet. The factory is 140 amp fuse. The fusible link would be better suited than a fuse. I've found a few trucks that is incapable of doing a circuit breaker because of mystery loads and causing the breaker to trip prematurely. Fuse will solve this problem but make sure to carry an extra fuse. Addon: Resettable Circuit Breaker I picked up an inexpensive 150A circuit breaker from Amazon. The breaker does the job but over time the breaker will get weak and trip prematurely. I still favor the circuit breaker over a fuse for the alternator protection. Fuses you might go through several and be left high and dry without a spare and unable to drive home. Make sure you buy plenty of spare fuses if you go that route. Even with my backcountry travels I still trust the circuit breaker better.

Alternator and PCM protection What I'm going to describe is a rare event. This is possible with any alternator stock ND or Bosch or even the aftermarket alternators that are bigger amperage output. In a nutshell, at any point, the blue field lead happens to short to ground the entire short is routed back through the PCM. Since the PCM is protected by a shared fuse of 20 amps this means the circuit board fails during these events. There have been two cases of this which is @pepsi71ocean and myself with the same failure. The only difference is mine failed so badly that it burned a hole through the PCM circuit board making the PCM unrepairable. I was forced to replace the PCM completely. Diagnostics You want to start the engine and check the blue for +12V. This +12V power should be present with the engine running. It's tested by using a DVM or test light. If power is not present then the PCM is damaged. The green wire will show a good ground more than likely but this will not work is there is no +12V to the field. This is where you make use of the article for ECM /PCM rebuilders. Make sure to test the alternator and replace it as well. The Modification This is based on the W-T ground wire mod. Being the field lead is powered from the PCM and the PCM, ECM and VP44 all share the same 20 amp fuse in slot G of the PDC. This fuse is too large to protect the PCM from a field wire short. This means you would have to purchase a fuse holder and solder in a fuse holder on the blue wire. With the PCM connectors removed from the PCM look at the connector towards the fender, this is connector C3. Pin 25 is the blue wire you can ohm test from end to end to be sure the wire is not broken. Then ohm between the blue wire and ground to verify its not shorted to ground still. Now take the tape near the loom and unwind it. This will give you about another 1 inch of wire. About 2 inches from the loom cut the blue wire. This should give you like 6 inches from the plug end and then a kind of stubby 2-inch wire on the loom end. Now solder in the fuse holder and use shrink tubing over your solder joints. With a bit of neat folding of the wire you should be able to loom the fuse holder into the loom again. I know that @IBMobile did the load testing of the field lead and suggests a 7.5 amp fuse. I'm going to do the testing with a 5 amp fuse. As for protection of the alternator on the charge lead, I opted to purchase a resetable 150 amp breaker. I know the factory alternator fuse was 140 amps. I know that the alternator will not produce more than 135 amps of charging current. I know the breaker is not there for protection the alternator for excessive charge current. The breaker is there just in case there is a dead short on the diode pack. If the short was good enough it could light that 6 gauge cable on fire. So having an exact 140 amp breaker is not required. The other thing I was reading up on was the breakers tend to trip prematurely because of underhood temperatures. I wanted to be just that little bit bigger that it does not trip the breaker because the alternator is already at full current charging on a hot day like jump starting another vehicle. Fallout, External Regulator users As for all you as fallout from this problem you typically were doing the external voltage regulator because of the PCM failure. I'm going to suggest that you consider doing the PCM repair and doing this mod and getting away from the external voltage regulator.

Mike is correct...the large current load on these 3 phase hairpin stators in conditions where all the available current is delivered does tax the design of the factory alternators. The diode's are all created on a single silicon substrate to assure uniform junction characteristics. This method allows for the PIV (peak inverse voltage) to closely match across all six diodes in a "three phase" rectified bridge. The old school would be to use individual large stud mounted diodes however; they would have to be curve traced to create a matched set of six diodes with close PIV and forward current avalanche voltage drops. All silicon diode junctions have a .6 volt drop turn-on when forward biased or conduction. Variations of these characteristics cause a dirty wave-form of the desired sinusoidal wave appearance. Hence; we have "ripple" witch is what Mike has explained so many times and why we must avoid this situation. Our trucks arrived with a "bare minimum" alternator design to get the vehicles off the sales lot. The grid heater configuration along with head lights and a fan blower for heat or defrost on early cold mornings takes the demand for these wimpy alternators to their design limits. Once we begin to "pound or beat" these diodes into forward and reverse current conduction we begin to see changes in the silicon junctions. It is cumulative and in time between hot summer and cold winter conditions our diode bridges become "leaky" and the "ripple" (AC component) becomes excessive and certain electric system devices begin to balk or react strangely with the imposed "ripple" floating on the DC(direct current) rail. Excellent mil-spec electronic devices or space-bound instruments MUST HAVE bullet proof power supplies. PURE DC hard-core power supplies are normal components and can be built without much effort today. Our alternators and dual batteries ARE the DC supplies for our trucks. The error is budget on Daimler/Chrysler's decision to put these 135 amp alternators into the Cummins platform. The standard rule of thumb for all electronic design regarding power supplies is, "If you have a demand of 100 amps maximum in a given system, you build a supply with 50% more headroom minimum. Now, take conditions into consideration...heat, cold and perhaps a poor matched battery in a dual battery (paralleled batteries) storage supply and the occasional "starter" operation (the Cummins starter is INSANE on current demand!) and WE have a real MONSTER to feed! Boys and Girls...if you want bullet-proof DC, double the available current at idle. Yes...this is correct...go with a 6 phase (twelve diode pack) and a hand-wound "square wire" hairpin-stator. The six-phase stator and companion rotor will cut the ripple to near zero in conjunction with proper storage capacity (really good paralleled batteries) you will have the power supply for your Cummins. The "square" wire wind is best for current demand when an "AC field wave-form" is cutting the coil to impose current into the inductive system. It is the cutting edge in design for transformers with high efficiency and LESS HEAT. Heat is "loss" and also destroys the surrounding aspects of the generating device. BTW...not even Nations builds to these specifications....they buy their upper-end higher current devices from a source in Riverside California. Just for grins... 1 Amp...what is this? Electronics 101: Current flow is "electrons" ( remember 5th grade science?) the Atom is composed of three elements the Proton, Neutron and the little Electron flying around the other two elements like an orbiting satellite. It is the "electron" we are interested in when it comes to DC (direct current) when we refer to "current flow" in a circuit. SO...the question is? When we measure "current flow" the term Amps is used....how many "electrons" flow through a piece of wire at a given point in "one second" ??? One Amp is (physics term "Coulomb" ) equals 1x10 to the eighteenth power....hence; when you start your mighty Cummins you are transferring 1x10x18 x 600 electrons in order to spin the Beast into run condition ! Take a look at the size of this number ! This is why you need "FAT" wire to allow all those little (minions) electrons to race at the speed of light through the wire to the given load. As you can see...current flow is from "negative" to "positive" in our world. The battery has a "positive" terminal and it is "sucking" to become satisfied. It attracts ("sucks") electrons off the frame-rail of your truck "as current flow" in order to spin the armature of the starter motor. SO..."negative" (electrons) flow towards the "positive" (hole or sucking-action)....seems we have an "upside down" world !!!! Now this leads us to another interesting Physics observation...you see...lights Do Not Give Off Light ! They suck "dark" and you will notice when a light bulb "burns out" and no longer provides luminescence....we say "it is burned out" however; we now know that is not true!.... IT IS FULL of Dark and we need a new bulb ...Look at the bulb...it's "dark". Sorry...had to share this funny tid-bit...none the less...our Cummins platforms were not produced with Mil-Spec in mind. Sorry, our ECM and PCM's must be provided "clean" stable DC in order to function correctly. The design guys never considered 6 millivolts of "ripple" to be critical for converter "lock and unlock" syndrome and yet we see the result and unwanted operational characteristics. I build killer DC power supplies for various electronic devices...you need a shop oscilloscope to even see the minor "AC ripple" and as for regulation, from zero to 100 Amps at 14.8 volts there is NO DC drop in voltage. It is like taking and engine from "zero" to "red line" in a heart-beat and you don't even see a fraction of a voltage drop...this is called a "Stiff DC Regulated Supply". Build your DC Supply...the Cummins platform is a Nobel Beast....feed it a good stiff DC diet with NO sag and Zero ripple and all will be well. ALSO...guys I lurk around out here...I've seen photos you have all taken "under the hood" of your beloved vehicles...gosh golly!!! The appearance of the battery terminals and cable connectors...it is pretty sad. You can't transfer billions and billions of electrons (with NO heat) through the scum I have viewed. Again...No worries...we are all in this together... I share this respectfully as intellectual content with just a touch of humor Cheers

Huge thanks to AKshooter for writing this up. Ok, recent thread on here drove me past the point of looking at wiring diagrams and giving direction. Somethings are just easier explained with pictures and tested against a known good working system. So in an effort to help others, I tore my own truck apart in the dark outside in Alaskan November temperatures with a few simple test tools, a head lamp and an IPhone camera so bare with me if the pictures aren't the greatest. I do prefer that testing be done test light when possible. A meter is useful tool but if you don't 100% completely know how to use/test with it you can easily be lead in the wrong direction. Just throwing that out there from 11 years now of turning wrenches for a living. See it happen all the time. No current flow no voltage drop. Testing circuits when they are loaded is best. First of all you are going to have to look at a diagram, going to make you. On this diagram we can see - Powertrain Control Module or PCM - Controls Alternator Fields (Turns the alternator on/off) - Power Distribution Center or PDC - Fuse box under the hood - The Generator or Alternator - If you need this explained.... 1. There is a Black/Grey Wire between the Gen/Alt and the PDC which contains the 140amp fuse and then a red wire to the battery. This is the large charge wire that electricity flows from the Gen/Alt to the 140amp fuse in the PDC and onto the battery. This is the large wire on the large stud on your Gen/Alt and you should have battery voltage or alternator output voltage on this stud. Check the fuse if you don't, or wires associated with that circuit. 2. Now into the meat of things, there are two wires from the PCM to the Alternator. - Here is the two pin plug that plugs into the back of the Alternator, notice the Green and Dark Blue Wires. - The dark blue wire is the voltage supply to the Generator fields. Meaning this is a positive wire and should have 12V on a meter or light a test light like this when the test light is hooked to battery negative as in the picture. (A meter would be the same with the negative lead) Engine MUST be running, key on engine off does not work for this test. *For demonstration purposes pictures are taken with engine off so the test light is not lit in these photo's.* - The green wire is the control wire, meaning the PCM grounds this wire to turn on or off the alternator fields (DO NOT THINK YOU CAN JUST JUMP THIS TO GROUND FOREVER TO BYPASS THE PCM IT WILL FRY LOTS OF STUFF BECAUSE THE ALTERNATOR WILL BE FULL FIELDED TO 16+ VOLTS) This is a ground circuit so with the truck running a test light or meter hooked to battery positive should show 12V or light like this. If you have power on the blue wire while the engine is running and can hook 12v to ground on the green wire while the engine is running and voltage on the large stud your alternator is bad, but if you don't have one of the other......... This is where the PCM lives behind your air filter box, notice I removed mine for better access, TURN THE KEY OFF before disconnecting The connector closest to the passenger side is the Grey C3 connector. The Connector in the middle is the White C2 connector. Reference the wiring diagram at the PCM. We are concerned with pin 25 in the Grey C3 connector as it is the opposite end of the dark blue wire at the alternator. We are also concerned with pin 10 of the White C3 connector as it is the opposite end of the green wire at the alternator. NOTE - The connectors have a locking tab on the top and bottom, do not force, use shop air if need to blow out dirt so the locks release and you can unhook the connectors. Noticed the pins are numbered, double and triple check your are on the correct pin when testing. Grey C3 shown here White C2 shown here Now using your meter set it to continuity or resistance test and check between pin 25 in the Grey C3 connector and the BLUE wire pin at the alternator plug. There should be a connection between these two pins. Next test the Pin 10 of the White C2 connector to the GREEN wire pin at the alternator plug. There should be a connection between these two pins. Meters vary from make to make as to what they will read (some beep) when showing continuity vs an open circuit. Simple test is to simply look at what the meter says when the leads are not touching each other..... like this. VS With the leads touching each other. (no resistance, good connection) This is what you want to see when testing both of your wires between the PCM and Alt plug Now if these wires both test good, more than likely your PCM is bad. To be 100% positive it is the PCM, I would pull the plastic cover off of the C2 and C3 connectors and back probe the blue and green wires and see if you have 12Vs that way, this would eliminate the entire harness and test only the PCM. How you go about fixing the issue is up to you. With the manual transmission trucks that is all these two wires do. BUT with the Automatic trucks notice in the diagram that the BLUE wire also powers the transmission relay through a splice. I'll try to update this with information as to PCM repair or external voltage regulator solutions. Now if these wires both test good, more than likely your PCM is bad. To be 100% positive it is the PCM, I would pull the plastic cover off of the C2 and C3 connectors and back probe the blue and green wires with the harnesses plugged in and see if you have 12Vs that way, this would eliminate the entire harness and test only the PCM. How you go about fixing the issue is up to you. With the manual transmission trucks that is all these two wires do. BUT with the Automatic trucks notice in the diagram that the BLUE wire also powers the transmission relay through a splice. I'll try to update this with information as to PCM repair or external voltage regulator solutions. Hope it answers some questions. Engine running for testing at the plug. Key off before unhooking PCM.