Best Alternator for 1998 Cherokee? -
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post #1 of 3 Old 01-26-2012, 10:48 AM Thread Starter
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Best Alternator for 1998 Cherokee?

What's the best replacement alternator for my 1998 Cherokee 4.0??

You'd think it would be an easy question to answer. But of course not! Life is never easy...

So I start checking on various Alternators. I decide my best bet is to buy a new Bosch unit, either the standard 90 amp model AL6509N or their heavy-duty 120 amp model AL6510N. But then when on the NAPA site, I saw something that caught my eye: According to the detailed description, these alternators both have INTERNAL voltage regulators [ EDIT: This info on the NAPA site and other sites is wrong, as both of these Bosch Alternators DO NOT have internal regulators according to a Tech Support guy at Bosch (see my next post for full explanation) ]. Yet other Alternators (such as the NAPA brand remanufactured and new ones) claim they are for EXTERNAL voltage regulator systems. I THINK (but do not "know") that 1998 Jeep Cherokees have "External" Voltage Regulators as part of the PCM (computer). So if that's the case, these Bosch units really have Internal VR's then they're no good for the '98 Cherokee. And yet, according to every online parts seller, they're listed as compatible (but so are the External VR type ones).

So I did more checking, and I found a thread on another forum by a guy who put one of these Bosch units in his mopar car and it fried his harness (like our Jeeps, his "external" Voltage Regulator is part of his PCM).

So, what gives?!?!?! Do these two Bosch models really have internal regulators, or is just a mistake on the NAPA site? I can't believe they'd be incorrectly listed. And if that is the case, I can't believe only one guy in the whole world has fried his wiring harness by putting on in his car that really needs an alternator without a built in VR.

I even tried contacting Bosch. They're supposed to call me back. And I called my local Jeep Dealer parts guy. He thinks the '98 Jeep's Alternator has an INTERNAL regulator - but he said he's just guessing as "all modern alternators have internal regulators" - which is NOT true in the case of cars with the VR as part of their OCM or ECM (computer).

Question #1: Does anyone out there know for sure whether or not these two Bosch Alternators (AL6509N and/or AL6510N) do or do not have Voltage Regulators built into them?

Question #2: Has anyone out there put a Bosch AL6509N or AL6510N Alternator in their 1997 - 1998 Jeep Cherokees and if so, did it work?

Question #3 If anyone put the 120 amp AL6510N into their Cherokee 4.0, did you have to modify (grind) the mounting brackets to make it fit?

Question #4: What other Alternators do you all recommend? I'm looking for new ones with lifetime warranties, and I wouldn't mind if it put out more than the stock 90 amps, but I don't want to spend more than $200.

Thanks a bunch!


P.S. On an unrelated subject, it's been a LONG time now since I went through that debacle with Bosch brand O2 sensors frying every few weeks. Since I put a MOPAR O2 sensor on, everything has been fine in that department. Bosch O2 sensors do NOT play well with Jeeps!!! (But I hope maybe their alternators do).

Last edited by mdtobe; 01-28-2012 at 04:56 PM. Reason: To provide correct info I received from Bosch.
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post #2 of 3 Old 01-26-2012, 11:08 AM
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Descriptions on parts websites are not always written by people who know anything. OBD-II XJ alternators are regulated by the PCM computer.

"Best" is what fits right and lasts longest. Buy a new alternator, it will last longer than a Chinese rebuilt. Stick with brand names like Denso, Bosch, and AC Delco. has the best website, best selection of parts, and the fewest mistakes. If nothing else, use it to find part numbers to take to your local store.


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post #3 of 3 Old 01-28-2012, 04:50 PM Thread Starter
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I received a phone call back from Bosch's Tech Support. It seems the NAPA website description (and a few others) is wrong. Both the Bosch AL6510N and AL6509N do not have internal voltage regulators and work fine in the '97 and '98 Jeep Cherokees which have the voltage regulation done by the PCM. The 120 amp AL6510N does have a larger body on it and would require some modification of the mounting bracket(s) and possibly some wiring modifications, so I elected to order a new 90 amp AL6509N through (only $97!!!). I don't run anything beyond stock, save for the European H4 headlights, which aren't all that much more current-hungry than the pathetic US-spec original headlights, so the stock output of 90 amps will continue to be fine for me. No nuclear stereo, no roof lights, no winch. Just a plain ol' Cherokee with some good tires, good Rancho shocks and an amazing engine that even at 180,000+ miles, uses no oil between oil changes.
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alternator problem , alternator replacement , bosch auto parts , charging system

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