Nope no datasheet came with the alternator. It has the same connection points and such as the stock one.

If I remember right, from all of the testing that I have done. That there is zero voltage at the small terminal, no matter the position of the ignition without the exciter wire attached. I will check the voltage reading between the posts with the main wire attached tonight. I am assuming it should be battery voltage, correct? I will check the main terminal to a good ground and then to the small terminal for a reference point.

Just for my own insight, what is happening in my car is preventing the bulb test mode? I am assuming that is the reason behind this whole debacle. I assuming that the voltage of 12V on the exciter wire is too much and that is causing what in this case? Sorry just trying to understand what we are chasing down in order to better understand the isuue and testing being done.

How does the voltage getting limited before startup, at the on position, to 1-3V, on the exciter wire? I this is where the problem is due to the voltage at the on position being 12V.

May have some additional time tonight to do some more testing , I will be pulling the alternator to get a picture of the alternator minus the brush holder. I am assuming that is the small black piece on the back with what looks to be a spade connection almost opposite the voltage regulator.

Thanks again for all your help everyone, I would be lost without you guys!

 

The exciter terminal on the alternator with no connection should be at ~0V when only the B+ is connected to the battery.

The exciter wire provides current to the rotor winding when the ignition is on via the regulator before the alternator starts generating. Without the initiating rotor current there is no rotor magnetic field and there is no generation. So when initially started the alternator needs this boost. At this time the voltage on the exciter will be quite low - probably 2-3 v max. This causes the charge light to come on and initiates the bulb test.

When the alternator starts generating - it drives the D+/(61) terminal itself up to 12+V (~whatever the system voltage is). This both makes the dashboard charge light go out directly - and the dash monitors the 61 line and when it sees a high enough voltage (close to 12v) it ends the bulb check on all the other bulbs too.

Since your exciter circuit seems to go to 12v immediately - there is no bulb check.

On the face of it - based on the symptoms - it would seem your alternator is faulty... Quite possibly the 61 circuit is just open circuit internally.

Alan

 

I tested across the terminals, b+ terminal voltage from the battery is 13v. I have a trickle charger on board. The voltage across the terminals is 8.4v with the red lead on the b+ post and black on the 61 terminal. Reverse is negative at 8.54.

Is there anyway to test to see if the 61 terminal is open circuit internally to the alternator? Should it have continuity with case then?

 

Your test seems to suggest it is not OC.

However your results this time are not consistent with the results last time (where it was basically battery voltage).

Seems the measurements are a bit inconsistent...

Alan

 

Alan, I did your test below, main cable on B+ supplying 13v from battery tested to the bare 61 terminal on the alternator. The exciter wire from the car was not attached. It is 0v ignition off, 12v with ignition on, and 12v engine running ( not charging). That remains consistent.

 

This makes no sense. As describes, with only the thick cable from the battery connected to the B+ terminal on the Alternator (You state the exciter wire is disconnected) The measurements of voltage between the B+ terminal and bare 61 terminal can not change ign on vs ign off as there is no connection between the alternator and ignition switch to make that change. Unless the wire you disconnected believing it to be the exciter wire is something else and there is a real exciter wire hiding somewhere else.

 

Here is a shot of the new and original alternators:




I took everything off the new one that I could:

 

who makes the brush holders for both of the ones you have?
Your new alternator looks quite different ( smaller) you might have to get another one,

I would also guess that the black housing insulator on the old one where the wires connect should be swapped over

 

Agreed - if the only connections are B+ and the case ground then how does the alternator even know if the ignition is on or off.

All through this saga the measurements seem very inconsistent and many times have been non-feasible.

Matt are you sure you are using the meter correctly? This is very important.

Your ground terminal must always be a good solid true ground on the vehicle, a (labeled) ground point is ideal - but an alternator case bolt will work too. You must be on a 20V (DC) range and use the appropriate terminal on the DMM (Volts). Make sure it measures a realistic battery voltage as a quick test. Perhaps change the DMM battery to ensure its fresh.

Alan

 

See Below Post

 

No, I tested between the B+ terminal with the main cable attached to the 061 and got about 8.4 -8.5V. I didn't mess with the ignition becuase as you guys are saying it does not have any impact on this test as there is no connection to the ignition switch since the exciter wire from the car was not connected.

This remains constant so far and was in response to Alan's question about voltage and things changing:

Exciter wire is 0v ignition off, 12v with ignition on, and 12v engine running ( not charging). That remains consistent.

I am absolutley using the meter correctly. All of this is still valid:

1. Battery Replaced and is known to be good.
2. Voltage ~12V at Starter
3. Voltage ~12V at Large Terminal (B+) on Alternator
4. Voltage ~12V at Small Terminal on Alternator, with Ignition On
5. Voltage ~12V at Jump Post
6. No Low Voltage Light On When Car Is On or in Test Mode
7. Small Wire Terminal Grounded Out and Low Voltage Light Comes On
8. Alternator Tested Good, Diodes, and Exciter were checked, it was putting Out Around 14V.


Problem is that the 12V does not get limited to around 3V with the ignition in the on position. I think the only thing that affects this is the regulator, correct?

 

See the response above.

 

Yes only the regulator is connected to D+ internally.

So if everything is as you say here AND the alternator never generates - then it seems the alternator must be faulty - regardless of how it was tested before.

I'd still like you to test as I asked before - what you say you did was different than what I suggested. Don't measure voltage between B+ & D+ - always reference each to ground.

With only B+ and ground connected what does to terminal (no wire) D+ measure at?

Alan

 

the no name brush holder should be removed from service,
install the bosh unit for testing if the brushes are questionable.
ONLY use Bosch parts for the charging system,
they will pretty much guarantee continued service

 

Merlin I was thinking the same thing, I will throw the Bosch regulator on there and see what happens.

Alan-

1. B+ has battery cable hooked to it as well as jumper wire.
2. Hooked the jumper wire up to a known good ground.
3. Tested the D+ terminal and it was .08V on the meter.
4. B+ terminal voltage to ground was 12.55.