my crd quit charging. 140k no shame.
figured its alternator, so removed to get tested.
advance & autozone both say cant test on thier machine?

I'm not certain but I think it's controled by the ECM or another computer that they can't duplicate with their tester

How is the "decoupler" (pulley)
At 41k mine is locked up and is punishing the belt and rollers
It can also fail and free wheel in both directions and not drive the alternator

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Atlantic Blue 06 CRD Limited (his)
Joined by a 2000 XJ Classic (hers)

What year is your CRD? The early ones up to about 05 I think has an alternator without a built in regulator. The field coil is controlled by the ECM which supplies a varying Pulse Width Modulated ground signal to the field coil to adjust the voltage output. The newer CRDs have a built in regulator but relies on a "wake up" signal from the ECM to start charging.
I only have the circuit diagrams for the 2002 CRDs and gassers.....CRD is Export obviously... but the basic principles should be the same for later models.
My diagram shows that the positive side of the field coil gets voltage from fuse 6 (30 amp) in the PDC, goes through a contact in the Auto Shutdown Relay in the PDC and finally goes through fuse 16 (15 amp) to the field coil.
Also the output from the alternator to the PDC and battery is actually a Fuseable link so that may be blown!

Definitely check the clutch on the pulley as stated above and maybe re-plug the connectors on the ECU after disconnecting the battery. Check all fuses , Fusable link and the Auto Shutdown Relay as well.

Try find a circuit diagram for your year model!

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2002 Export CRD 2.5 Sport

I'm not competent to read them but the wiring diagrams for 2005 and 2006 are in the FSMs that can be downloaded from Sir Sams NOOB guide.

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

ITS FIXED!! lucky guess alternator.
Which i got at pep boys for $158.00 in 24 Hours!!
they showed "one" in their parts depo.
Advance cant get, autozone says they can, but when they go to order its unavalible.
So pep boys has one crd core at least.

I work for jeep and have acess to both the 05 & 06 manuals.
Could not come up with any tests to detemine if no charge was due to generator ,
or pcm [voltage regulator].
Had code in it for low system voltage, checked flow chart and it does not have you check for voltage out of generator
Mileage was the big factor in me deciding on alternator.