Alternator has a clutch assembly on the pulley

ctdcrd · **Posted:** Thu Jun 17, 2010 8:03 am

This is great site. Thanks to all for the good info and I hope I can add to the data with this story.

The check engine light came on as it does with regularity. Most of the time it resets itself and is of no consequence. I was out of town when it came on this time and advised my wife to keep driving without checking the code. ( I keep an OBDII reader in the KJ because it does this frequently.)

Well, she drove it about 400 miles whilst I was out of town and the machine performed OK. However, it was apparently operating on battery power only with no alternator recharging most of that time. As she left the house one evening the charge symbol came on with the battery symbol. Then the ABS symbol came on followed by the brake symbol. She turned around and parked the Jeep. Later, when she tried to start it the starter solenoid clattered as they do with a dead battery.

I got home the next day and put the charger on the battery so I could get it tested in the morning. Before I pulled the battery I started the car and all the lights were gone except the CEL. The system voltage was battery voltage. I shut the car off and reconnected the charger for 15 minutes. The OBDII reader showed these codes:

P670
P1140
P0562
P1854
P0401
P0093
P0299

Restarted the car and system voltage was 13.3, a little above battery voltage.

The diesel ran fine except I could hear a faint metallic tinkle while it was running. There was a dusting of reddish powder around the alternator, radiator fan shroud and battery. But there was very little powder inside the alternator. It was blown inside, not coming out of, the alternator.

Checking with AutoZone, Advance Auto Parts, O'Reilly, and NAPA I discovered that no auto parts store could get an alternator. Jeep wants almost $500 for the new device. So I called United Rebuilders in Seneca, SC and described what I had. Brad told me about the pulley clutch. So I pulled the thing off the car and ran it down to him.

Mike changed the pulley while I waited and the charge was $55. I reinstalled the alternator with a new serpentine belt and life is good again. I cleared the codes and they have not come back in 25 miles.

The real point here is that the alternator looks fine and no information points to the charging system until the car dies from a dead battery. You could wind up with two trips to the shop, first for a new and expensive alternator then a return for the clutch after it tests OK in the shop but stops working again when you get home because the evidence shows the clutch is intermittent.

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

ctdcrd,

Here is a breakdown of your fault codes:

p0670 - #4 glow plug, either failed or due to low system voltage
p1140 - intake throttle (FCV) failed
p0562 - alternator charge control failed
p1854 - airbox pressure sensor not plausible (located on the side of the airbox)
p0401 - EGR sticking closed
p0093 - large fuel leak...due to air infiltration
p0299 - turbo underboost, typically related to the sticking EGR

Now that you have the alternator fixed, you should recheck the codes after a couple days driving to see what returns. Some of these codes are not related to the alternator issue...like EGR issues, and the fuel leak.

ctdcrd · **Posted:** Thu Jun 17, 2010 12:05 pm

Thanks, GreenDieselEngineering

So far so good. It appears that low voltage causes the computer + to change to - because the signal doesn't meet the threshold of voltage for a good (+) signal so registers (-)? But we're paying attention.

Thanks again.

Paul

Alternator has a clutch assembly on the pulley

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