If you have your alternator tested at Autozone - please tell us which cables/adapters

EDIT: Added cable reference for the air-cooled Bosch 120 as per bluebee.

JimLev found out the hard way that not all Autozone stores carry the necessary cables/adapters to test the water-cooled E39 alternators:
- E39 (1997 - 2003) > Alternator failure

Originally Posted by JimLev

AutoZone's cross reference hook up book for the water cooled alternator calls for them to use cable #xxx?? which doesn't connect to this alternator. He looked at every connector he had and none of them fit.
He then told me they couldn't test them.

Since you're often imobilized with the alternator out, & so that that the NEXT person can simply CALL ahead to determine whether their local Autozone has the RIGHT cables in stock ...

May we ask in this thread that the next few people who go to Autozone to get their alternators tested list below what the cable part numbers turn out to be, particularly for the water-cooled E39 variants?

- M54 Bosch 120: Test Lead P/N=12281 Dura Adapter=N-09
- M54 Valeo 120: Test Lead P/N=? Dura Adapter=?
- S62 Bosch 150: Test Lead P/N=? Dura Adapter=?
- S62 Valeo 150: Test Lead P/N=? Dura Adapter=?
- ? other alternators ?

EDIT: Looking at the pictures below, it looks like Autozone uses various terminology for the test lead and for the adapter. I tried to use their terminology in the table above - but I may have it wrong - so if I do, please correct as needed.

Here, for the record, is what my local Autozone used for the air-cooled 2002 525i Bosch 120 amp alternator tests:

Originally Posted by bluebee

Interesting.

We should probably document WHICH cable part number they need so that OTHERS can avoid this problem (especially if they need to borrow transit while the alternator is out).

If we can get someone to report the cable number needed, folks can CALL AHEAD to ask if they have it in their drawers.

For example, here is a screenshot from my alternator thread showing an Autozone part number 12281 and a cable adapter N-09 needed for my 120 amp Bosch air-cooled alternator.

Note: I'm not sure what the "12281" indicates - as it could indicate either the alternator or the cable - I can't tell from my picture below which it applies to.


Here is a picture of the actual cable he used for my Bosch 120A air-cooled alternator:


And, in his machine, he had these cables:


And these adapters:


So that others can simply call ahead in the future to see if the right cables are in stock, the question we'll need the next person to answer for the water cooled alternators is what cable and what adapter number does Autozone use?

Do you really believe Donna, that people will carry this knowledge around with them and automatically head for autozone? You start some of the craziest posts. No wonder you are at 12,000 posts in 3 years!Thats like 10 a day average-Yikes

Still lurking cuz Q prompted introspect...Barely

One can test their alt in the privacy of their own driveway, using a DMM.

1. Measure the battery voltage at start of day, with engine off. S/b 12.5V+

2. Start the car and run the engine at 1000 RPM. Battery voltage s/b 14V+

If you have the high cluster, you can use test nr 7.

If, on test 2, the battery voltage does not increase beyond test 1, the alt is not working.

Originally Posted by 540iman

You start some of the craziest posts.

I'm confused: Do you disagree with the goal or the method?

The goal is for us to create a table of which adapters are needed for each of the E39 alternators ... so that people can avoid the problem that JimLev mentioned.

The method is for the 'next' person who gets his alternator tested, to simply write down the cable & adapter used.

Which do you find crazy - the goal or the method?

2 things about bluebee:
1) she is thorough
2) she likes to help

In this case, JimLev would have been helped if he had been able to call ahead and check. Certainly finding out what the correct connector is will save someone else time in the future. 540iman, I think this is one of those "if you don't have anything nice to say..." moments.

Personally, I think Ed's method is the most practical for an alternator in your car. But say the one in your car failed, you took it out and rebuilt it. It might be easier then to stop by an Autozone and test it before reinstalling it.

I wanted to test a used alternator that I bought for $175, the seller said it was good.
AutoZone did tell me that they could test it, when I got there they found out they couldn't.

Testing it in the car will work most of the time, but it won't tell you if it can output the max current that it is rated for.
For the M62tu engine make sure F15 and F18 are not blown, your alternator will not work.
Haven't looked at the aircooled units fuses, might be the same ones.

Same thing happened to me.

Brought salvage alt to autozone, but they had only one of the two adaptors needed.

I wouldn't have known to call ahead, but now I do.

More detailed information about the V8 testing problems were posted just now over here by JimLev:
- E39 (1997 - 2003) > 540i water cooled generator/alternator

Originally Posted by JimLev

The point I was trying to make is the AutoZone book lists a cable for the water cooled alternator but it doesn't fit the alternator.
In order for them to put the alternator on their test fixture it needs to be mechanically mounted to their test stand. They don't have any way of mounting this alternator, it doesn't have a thru bolt hole like the air cooled alternators have.

Does anyone know if autozone can test the e65 water cooled alternator. I hear it requires special tool or connectors

Originally Posted by mjquake

Does anyone know if autozone can test the e65 water cooled alternator. I hear it requires special tool or connectors

No they can't, there is no way to physically mount this alt to their test station. They don't have the correct electrical connector either.
You e65 alt is the same as our 540 water cooled alternators.
If it's still in your car get a volt meter and measure the output voltage. Depending on the engine RPM, the level of charge of your battery, and what electrical things are turned on your voltage will range from the low 12 volts to ~14.2 volts.

Here's a heads up regarding alternator output tests vs battery voltage. Low battery voltage does not necessarily indicate a bad alternator. It may be resistance in the charging circuit although the alternator is fully functional.

Years ago, I had a car that began indicating low voltage (had a voltage gauge in the instrument panel) as I turned on high load circuits on, e.g. rear window defogger, HVAC blower high, electric engine cooling fans, high beam headlights, etc. The symptom looked like a weak alternator that couldn't put out rated amperage. I was pressed for time so I took the car to an "expert" auto electrics shop & described my symptoms but not my diagnosis. Next day and a $700 alternator rebuild later I had exactly the same problem! Shop said to come back & they would diagnose some more - "but the alternator did need repair." They even told me that the carbon pile load test indicated 125 amps but my car specs called for 130 amps. Yeah, right. What a load of CYA BS.

Instead I did my own diagnosis. I found the problem by turning on lots of high current circuits and measuring voltage between the alternator output post and the +ve battery post. I found a 1.75 volt drop. With no electrical load except engine and fuel pump ~0.25 volts. Ah ha - the high alternator output current was generating a voltage drop across resistance somewhere; reistance that shouldn't be there.

It was then easy to isolate the problem spot by checking intermediate locations. The problem turned out to be corrosion in the +ve battery terminal - inside the socket in the terminal that the heavy gauge cable fit into. I also noticed that the terminal became very hot with high current draw. When I cut & drilled, I found powdery green corrosion. Trimed & cleaned up the socket and cable back to clean metal, soldered the cable back into the terminal socket => problem solved.

The charging circuit configuration was the same as our E39s: alternator to starter to battery. All car circuits were taken from battery post; none directly from the alternator post. With this configuration, 100% of current drawn by the car is taken from the battery terminal. So any alternator output used for car circuits has to travel the charging path. Im my problem, the higher the actual alternator output, the lower the voltage at the battery post. Not an obvious result, at least to me at the time! This type of voltage drop would include that measured by the instrument cluster voltage test in an E39.

Note too, that the E39 circuit has an additional connection point between the starter & battery underneath the floorpan below the driver's seat. Another potential corrosion / high resistance point.

If this post seems to you to be a highjack, my appologies. It seems relevant to me since it relates to identifying weak or failed alternators - corretly.

I'm going to take the liberty of adding all the useful information above to the canonical alternator testing thread so others find it more easily:
- DIY how to test a BMW E39 battery & alternator