Catastrophic Alternator Failure
Posted to Technical Discussion Forum on 5/13/2017
56 Replies
Hello, this is strange, and dangerous, to say the least. An
IATN member contacted me about a 2014 Grand Caravan, with
only 54,000 miles, that wasn't charging at all, and no MIL,
no charging codes. OK, to begin, there is a recall on
Chrysler products with the 160 amp alternator, that have
sudden, and dangerous alternator failure, that sometimes
catch on fire, and can burn the vehicle to the ground, and
can be dangerous to drive when this failure occurs, and
frequently no MIL, and no battery failure light. This
vehicle is not on the list.
So now the question is how to quickly determine if the
alternator is bad. How to know for sure without messing
around. This is the new "B" Chrysler charging system. On the
alternator there are two small pins. One should measure 2.4
K ohms to the output post, and the other about 3 ohms to
rear alternator case. One pin measured 2.4 K ohms to output
post, but the other measured 1,400 ohms to rear case. I was
going to suggest a full field test, but no, the field
circuit is blown, so no reason to do this.
My friend removed the assembly. The brush unit and terminal
assembly are held into the rear case by four screws.
Initially the brush/terminal assembly would not lift out.
Why? There can be only one reason. Extreme groves in the
slip rings, that why. Finally my friend extracted the brush
unit. I never ever, in fifty five years of fixing
alternators, saw slip rings this badly gouged out. They were
completely destroyed, and at only 54,000 miles.
So why no MIL, no battery light, and no warning? I have no
idea. Why this extreme failure at this low mileage, no less
on a Denso? Denso alternators are known to be extremely
good.
I can't post the pictures of the extreme slip ring damage
because I don't know how to do this. But my test, to measure
field continuity, and integrity of the sense line, takes
almost no time at all. If it fails this test then you don't
even have to think about a full field test. This is a 100%
test. If it fails you can be 100% sure the alternator is
bad. Louie
Louis Bernstein
Owner/Technician (Retired)
Louie's Service
LeRoy, New York, USA