Ok guys, lights dim in a cyclic fashion at road speeds (read, 1500-2000 rpm) voltage is reading from 13v to 15v I can do it in park by giving it some throttle and turning on the light bar, headlamps and fog lamps, and turning on the blower fan.

I have replaced all of the idler pulleys (including the tensioner pulley but not the tensioner) and the alt decoupler, however, the tensioner jumps around a decent amount (witch is why i replaced the alt decoupler, and compaired to a new one, the old one had alot of play in it from forward motion to reverse freewheel which was tight, and not free at all) I replaced all of the idlers because while i had the belt off they did not spin smoothly. And i replaced the belt.

Could the tensioner be defective? could it be the cause of the tensioner jumping around? and could it be the cause of the voltage jumping around?

Or could the alt be defective and causing a cyclic load on the aux drive (fan belt) and causing the tensioner to jump.

With the alt disconnected electrically from the battery, i can not reproduce the voltage spikes.

On shutdown the (i suspect) new alt decoupler chirps. Is the new alt decoupler defective?

It seems to freewheel much more easily than my old decoupler.

I changed all of the parts about 3 weeks ago, and had no problems until now (except for the tensioner flapping around and making noise)

HELP this is driving me nuts.

_________________
06 CRD Limited. IMII, GDE TCM, Carter transfer pump, Upgraded oem primary, 2 micron secondary, 3 inch mandrel straight pipe.
Transgo shift kit, EHM, fcv butterfly removed, egr plated off. 19 3/8 solid flex fan, no electric fan, 10k lb aux trans cooler.
Frankenlift II, Mopar skids, allj's rails, 235/85 km2 on stock rims

Mine drops voltage for a second occasionally, always has-unsure why.

I would think your tensioner would really have to get loose to cause the voltage to drop like that.
But, you are putting quite a load on the electrical system so it has to be the alternator slipping or maybe an intermittent connection in the alternator itself. You might try taking the alternator to a parts store that can run it and see if the output is steady.

_________________
SOLD 2005-Eco & TCM tune-no elec fan-F37-#3 TC
Now have 2009 Durango

Taking the alternator to a parts store will only verify that you have... brought a "working" (according to them) unit into the store. Their system can't load an alternator enough to duplicate this problem.

This is your alternator on it's way out. I had EXACTLY the same problem, but it was happening more at night when the lights were loading the alt more. It did happen during the day too. I drove with it like that, doing it intermittently for a LONG time before I went to change the decoupler... And screwed that up, so I wound up changing the entire alternator. Problem vanished instantly, has not returned since.

Advance Auto Parts can get a complete alternator with the right pulley for $155. They may have to order it in, but they can get it. MUCH better price for the same unit that you would get from a stealer for $300+. Change the bugger and enjoy your clean power.

_________________
Proud supporting vendor of LOST Jeeps
TRAVELING CRD TECH. I come to you!
Need help? Just ask! I've taken it apart more than most.
Email jeep [at] maincomputer [dot] com - BOARD MESSAGING IS BROKEN
Over 225 CRDs currently driving with my valves, timing belt, rockers, or ARP Studs.
Bad noises = REALLY bad things.

With your engine running, use a battery load tester and load the alternator for a second or two, be ready to release the test switch. Watch the voltage and look at what the alternator does, if the belt slips or the tensioner jumps around, you have found your problem. If your alternator to battery fuse is junk and causing high resistance, you will pop it fast and that may be the problem. The fuse is sized to handle the full current the alternator can produce, so if it pops you have found a problem, not wasted a fuse. If you do not detect engine/alternator loading when you do the battery test you may have a problem. A crappy battery with one weak cell can cause problems that look like an alternator problem, check the rest voltage should be a little more than 12 volts. If your battery voltage drops below 10 volts when cranking you have battery/starter issues. If the starter test OK on current draw, the battery may be causing the problem.
Good luck
Note, load testers for gassers are too small to test the battery our CRDs or even a TDI requires to start. You will need to have a parts store test the battery. But the gasser battery tester will load the alternator just enough for brief testing.

_________________
2006 Pearl Green CRD
Magnaflow 2 1/2" Cat Back
KJ Extra Leg Room Brackets, Carter Lift Pump, V6 Airbox, ORM
Fuel cooler, Oil Separator, Progard 7
Gauges EGT Boost Trans Temp Oil Pres, Michelin LXT AT2 245 70 R16
7,000# Draw Tight hitch, PML EX Deep Trans Pan
Centrifuge, SunCoast, Transgo, RAM TCM, InMotion Stage 2
Wife's 99 TDI VW Beetle

Same group size battery in both the CRD and gas KJ's(except for '02's) so that does not matter one bit.

Beg to differ on the load tester, not all the load testers like the ones used years ago that are picked up a Garage Sales or from Harbor Freight are big enough to test a high capacity battery used on a CRD. Not all of the members have all the tools that are shoved at dealers in their home garage (some of which the techs have no clue on how to use in some dealerships). Shops and pars stores who sell batteries, do have the tools.
Point is to test the alternator load output for someone who does not want to visit a dealer and get hosed.
Sorry if thinking outside the Dealer Party Line box offends anyone, but getting the job done is what counts. Not kissing up to some pin head procedure written by a desk jockey with carpal tunnel syndrome in their right index finger. Proof of desk jockey incompetence are all of the errors found in the official Chrysler KJFSM that I paid for. The Bentley FSM for my Wife's TDI has a ton of errors also and even with the corrections and upgrades I paid for, it is a disappointment to say the least.
The FSM is a place to start as are procedures, but when the procedures that work ~95% of the time, don't work, it is time to figure out how the system works and go to the next higher level the Engineers have not thought of yet, I do it all the time.

_________________
2006 Pearl Green CRD
Magnaflow 2 1/2" Cat Back
KJ Extra Leg Room Brackets, Carter Lift Pump, V6 Airbox, ORM
Fuel cooler, Oil Separator, Progard 7
Gauges EGT Boost Trans Temp Oil Pres, Michelin LXT AT2 245 70 R16
7,000# Draw Tight hitch, PML EX Deep Trans Pan
Centrifuge, SunCoast, Transgo, RAM TCM, InMotion Stage 2
Wife's 99 TDI VW Beetle

Alright guys, thanks alot for your help and ideas.
My major problem is that i cant figure out why it is reproducible in a particular rpm band

Anyway it is now intermittant, making it more annoying.
For the price of the tensioner i could buy a new alt. So i do not know witch way to go
I'll figure it out eventually.

_________________
06 CRD Limited. IMII, GDE TCM, Carter transfer pump, Upgraded oem primary, 2 micron secondary, 3 inch mandrel straight pipe.
Transgo shift kit, EHM, fcv butterfly removed, egr plated off. 19 3/8 solid flex fan, no electric fan, 10k lb aux trans cooler.
Frankenlift II, Mopar skids, allj's rails, 235/85 km2 on stock rims

Your tensioner does not make power. If you can press on the belt in an open space between pulleys and it is firm, does not deflect more than about 3/4" or so... The tensioner is probably fine. Another way is to watch it closely while the engine is running. If the belt doesn't look "out of focus" from vibrations, The tensioner again is fine.

You are having a problem where the field windings are fluctuating in their output levels. The voltage regulator is built in to the unit, so it receives the 3-phase AC power from the field windings and through a bridge recifier, forces that voltage into high-voltage DC. Then it steps this down to low-voltage-high-amperage DC for the power needs. Unfortunately, the ability of the regulator to control the natural fluctuations of the engine at certain RPMs happens to coincide with the problem areas in the regulator's own circuits. The components are trying to do their job, but due to heat and lifespan, are interrupting the flow of power... For a moment. Then they cool and return to normal function, but the resistance is still there, so heat builds again until the flow is choked off... And the cycle repeats. The capacitors in the regulator have a lifespan. You have reached it.

Change the alternator, your problem will be solved.

_________________
Proud supporting vendor of LOST Jeeps
TRAVELING CRD TECH. I come to you!
Need help? Just ask! I've taken it apart more than most.
Email jeep [at] maincomputer [dot] com - BOARD MESSAGING IS BROKEN
Over 225 CRDs currently driving with my valves, timing belt, rockers, or ARP Studs.
Bad noises = REALLY bad things.

uummhh.. The voltage regulator is in the computer - PCM - it's not in the alternator.

it measures voltage in the system and if it> .5 volts off - sends a signal to the alternator to turn on. (unless the battery sensor overheats in which case it turns off)
FSM 8F-31

actually the section include battery testing procedures.

_________________
2005 CRD
stuff
Skeptic quod gratis asseritur, gratis negatur

You just defended my position with your description, but your first line is a bit off - Yes, the PCM detects and instructs the alt to activate, but that isn't a voltage regulator like I am referring to, or what is causing this problem. <edit>: I changed this opening, I think it sounded too confrontational in the original version. I'm not trying to attack anyone's knowledge or position, I'm only trying to add to the collective knowledge here. </edit>

I've had to learn a LOT about charging systems in the last few weeks, as I was diagnosing a charging problem on my motorcycle. The systems are different in that a motorcycle separates the components out, where the auto industry has been building them together into one casing for years.

The PCM in our jeeps is sending that signal to the alternator, yes. HOWEVER, that is merely a signal to energize the field coils. Without "flashing the field" the alternator cannot make power. The very next step is that the field produces 80+ volts ALTERNATING CURRENT in a three-phase configuration.

If the "voltage regulator" was actually located off-board of the alternator body, then there would be THREE heavy gauge (probably about 12 gauge) wires of the same color coming off the alternator. There aren't. The three-phase AC power is sent directly to the internal rectifier which bridges the voltage pulses (bridge rectifier diodes) and changes it to pulses of DC only. The system is still pulsing 3 times for every revolution, times whatever speed the engine is at. The voltage regulator further smooths this out by using a series of charge capacitors to accept power during the pulse, and release it during the slack time - Further reducing the effect of the pulsation. The voltage is then stepped down to a usable power.

There are several ways all this can be accomplished, but the simple fact is that all rotational-generated power is AC unless you have a dynamo making the power. It is easier to make 3 phase power and then rectify it out to whatever you need. The clearest indication of the design of our power system is that we only have 2 wires connecting to the alternator, one large (battery charge) and one small (field activation) with the body as the ground for the circuits and field signal. The three phase wires do not exist outside the casing, and do not ground to anything.

_________________
Proud supporting vendor of LOST Jeeps
TRAVELING CRD TECH. I come to you!
Need help? Just ask! I've taken it apart more than most.
Email jeep [at] maincomputer [dot] com - BOARD MESSAGING IS BROKEN
Over 225 CRDs currently driving with my valves, timing belt, rockers, or ARP Studs.
Bad noises = REALLY bad things.

700cca's is not a high capacity battery,more so any battery made in the last 8 years by Optima.

The alternator is internally regulated. The only external control is from the gatekeeper, in which it waits about some few seconds after the start to turn on the alternator which is done to improve cold start-ability. Otherwise, the alternator is like any other "conventional" alternator.

Right from the '05 FSM,goes for the CRD also.............

That is called flashing the field, TJKJ. As with many other things in service manuals, it is not entirely accurate to the individual component level inside a system-level part. The reason for this is simple: The manufacturer doesn't want the service tech mucking around at the component level, just replace the system-level part.

Hence why they say to replace the entire PCM if there is a problem with flashing the field... Or would you want a dealer tech to pull out his oscilloscope and soldering iron to find the IC that went bad?

Yea... Chrysler doesn't think the tech is capable of that. In this instance, I agree with them. None of what you posted changes the reality of the design: The signal from the PCM is nothing more than the gatekeeper that MrMopar referred to - It flashes the field, switching it on. The field coil then makes 3-phase power for the internal regulator to fix and step down.

The fact that the service manual called the PCM circuit a "regulator" is just proof that people who write manuals are not the same people who design the components. It is not a regulator, it is a detection circuit and an activation switch.

_________________
Proud supporting vendor of LOST Jeeps
TRAVELING CRD TECH. I come to you!
Need help? Just ask! I've taken it apart more than most.
Email jeep [at] maincomputer [dot] com - BOARD MESSAGING IS BROKEN
Over 225 CRDs currently driving with my valves, timing belt, rockers, or ARP Studs.
Bad noises = REALLY bad things.

Yeah you have no clue about automtive electrical systems.The rectifier bridge is in the alternator but the regulator is in the PCM.Most get those 2 items mixed up.


Oh and what do you think a regulator does? It turns "on" and turns "off" the alternator to keep the voltage at a specific mark,and that component in a KJ is in the PCM and not the alternator.The regulator does not step up of step down voltage,that is the rectifier's job.The regulator senses and turns the alternator on/off.

Go ahead and tear apart a KJ alternator and you will find only the rectifier bridge.


Oh and as far as testing the KJ's charging system you need the DRBIII(or starscan) and use it's internal scope to test the system.

Manufacturers have been using computer-controlled voltage regulation for many years.

_________________
2006 CRD http://www.UtahPowderCoatings.com/ http://www.gorecon.com/ I'm kind of a big deal.
RL rear bumper, ARB front bumper, Mile Marker winch, Power Tank, Skids by Mopar & Skid Row, RL Super Skink Sliders, 235/85R16 MTR, Air Flow Snorkel, DTT, 4.10 gears, Frankenlift II, Katskin leather, JL Audio stereo, Rosen video.

Yes, and all that the computer is doing is activating the field on the rotor. It is an electromagnet, without that smaller wire feeding voltage to the rotor, nothing happens in the main windings. The same system is used on Ford and GM, these are the so-called single-wire alternators. They really haven't been known as that for a while however, b/c cars with external voltage regulators to step that power down (Like the 83 Lincoln Town Car if you have a parts computer nearby) are becoming rare on the roads. I had one of those designs in my Town Car, and had to replace the regulator several times. It had about 6 wires on it IIRC. The main charge pin was still on the alternator body however, so I'm not sure how that design differed.

But you CAN test this single-wire design - The test bench at the auto parts store will put voltage into the field windings, and you should get 12v out of the main charge pin IF it is working properly.

In all the back-and-forth about this, I think I may have just realized what is causing the pulsations that I experienced on my CRD, and the original poster is having now: One of the brushes on the rotor is bad or has a weak spot on the shaft. It keeps hitting that weak spot every time the pulley turns over, and that causes the pulsations.

So still the same solution - Change out the alternator itself.

_________________
Proud supporting vendor of LOST Jeeps
TRAVELING CRD TECH. I come to you!
Need help? Just ask! I've taken it apart more than most.
Email jeep [at] maincomputer [dot] com - BOARD MESSAGING IS BROKEN
Over 225 CRDs currently driving with my valves, timing belt, rockers, or ARP Studs.
Bad noises = REALLY bad things.

Well, if the voltage regulator on a KJ is external from the alternator (i.e. in the PCM) then the
alternator can be tested on the bench at any auto parts store.
That old Lincoln you mentioned (with external regulator), when bench tested, will put out a
un-regulated 18-25 volts.
Therefore, the same should hold true for our KJ.

So, if the alternator tests good on the bench, how do you fix the regulator?

_________________
U.S. Army Retired

IIRC, the old Lincoln alternator put out something like what the magneto on my motorcycle does now - In excess of 30 volts at idle, 80+ at 4000 rpm. (Granted the Lincoln never would spin that fast, I'm just making an inference on that) but the theory is the same: Raw windings generating completely unregulated power. The difference is that on the bike, the primary on the rotor is a set of permanent magnets, so it is always on. Just like a lawnmower - start it up and it is making juice, as long as it spins. What you DO with that power is the problem, when you have too much. Hence burning the headlight, instead of overcharging the battery.

In our case, the "regulator" in the PCM is supplying a voltage to the primary to turn it on and off. This works because the primary on the rotor is an electromagnet.

I did some thinking about this today while driving around, and I think I now understand why the service manual refers to the PCM circuit as a regulator, even though in the strictest sense, it isn't stepping down the final stator winding voltages.

Everything about this is simple electron physics, manipulated to make power. A transformer for a cellphone does the same function as our alternators do, (magnetically inducing voltages) but does it without moving parts. One set of windings has a lot of wraps, the other has just a few. The rotor on our alternator (by physical space limitations) can't have that many windings, and we already know it cannot carry much voltage b/c it is coming direct from the PCM.

But... On a cellphone transformer, both voltages are constant, based on the supply side. IF the PCM was acting as more than just an on/off binary system, but was instead ramping that rotor voltage according to some scale, say a 5-to-10 volt input... Then the magnetic field strength would ALSO vary, so a very small change in the input voltage (easy for electronics to accomplish) would equal very large (comparatively) changes in the output voltage.

This would then eliminate the type of step-down circuits that my motorcycle has, and would only require the bridge rectifier in the alternator like TJKJ suggested, so that the output power direct to the charge pin was ready to use.

The parts store test bench will most likely only provide the "full field" voltage (probably 12v, but that is a guess) to the rotor field pin on the alternator, and if the field is fully operational (no bad brush like I suspect might be the root cause of the problem) then you should get ~14v out of the charge pin...

They can test it, PCM regulator or not.

_________________
Proud supporting vendor of LOST Jeeps
TRAVELING CRD TECH. I come to you!
Need help? Just ask! I've taken it apart more than most.
Email jeep [at] maincomputer [dot] com - BOARD MESSAGING IS BROKEN
Over 225 CRDs currently driving with my valves, timing belt, rockers, or ARP Studs.
Bad noises = REALLY bad things.

Gassers have PCMs (ECM and TCM in one box).
Diesels like our CRDs and the Cummins have a ECM and a separate TCM, sorry that is the way it is.

Try to locate a PCM for a CRD you will get strange looks if they are Polite and laughed at if they are not.

And besides, the voltage regulator for the CRD is located in the Body Control Module and not the non existent PCM. Assuming the Holy Grail '06 KJFSM is not again in error.

BTW: The voltage output of the alternator is regulating the electrical energy going to the rotor through the slip rings (unless it is brush less, our CRDs arn't). Since the voltage is easier to vary than the amperage to the rotor, the voltage regulator (separate, internal, in the ECM, BCM, or PCM)varies the voltage. When more charging voltage is needed the voltage to the rotor increases.
Personally, I would put a volt meter onto the terminal going to the non ground side of the rotor and see what the voltage is. If you have zero, try the other and see if you have some voltage, no voltage check for other problems like a loose or bad plug.
I would test voltage going to the rotor before I trusted a Steeler Space Cadet hooking up the Proprietary wizz box which can flash my ECM and TCM back to F-37 hell. I like to use the comparison of an attractive young woman in a cell block of convicted rapists not getting harassed or attacked.

_________________
2006 Pearl Green CRD
Magnaflow 2 1/2" Cat Back
KJ Extra Leg Room Brackets, Carter Lift Pump, V6 Airbox, ORM
Fuel cooler, Oil Separator, Progard 7
Gauges EGT Boost Trans Temp Oil Pres, Michelin LXT AT2 245 70 R16
7,000# Draw Tight hitch, PML EX Deep Trans Pan
Centrifuge, SunCoast, Transgo, RAM TCM, InMotion Stage 2
Wife's 99 TDI VW Beetle