Is my new Bosch alternator bad? - Toyota Nation Forum : Toyota Car and Truck Forums

tashirosgt · 08-06-2011, 12:42 PM

I measure only 12.3 volts across the battery terminals when my 1990 Corolla is idling. (On my 1989 Corolla, I measure about 14 V). I have a new battery and I've put on a new (i.e. remanufactured) Bosch alternator. Is there a quick test that will determine if this new alternator is bad?

The "charging fuse" is OK. The directions that come with the alternator say to run the engine and measure voltages from the alternator body to the negative battery terminal. It measures only a few hundreths of a volt, which checks. It says to measure from the "+ terminal" on the alternator ( I assume this is the one that takes the bolt-on connector.) to the postive terminal on the battery. This measures a few hundreths of a volt, which is less than the max of 0.7V that the test demands.

SuperRA · 08-06-2011, 01:17 PM

That's usually the test that I do. (volt meter on batter when running) What is the voltage of the battery as the car is off? If it's the same then something is definitely wrong with the charging system. Now that doesn't necessarily mean the alternator, but usually it is.

Most parts stores will test an alternator in store for you. I guess you could try that too.

90 GP · 08-06-2011, 03:01 PM

Don't know where you bought alternator but AutoZone and Advance do free charge/battery system tests. They usually give you a printout when completed.

tashirosgt · 08-06-2011, 06:43 PM

I tried installing a second new alternator and I only get 12.33 volts across the battery terminals with the engine idling. The battery is new. I tried changing the charging fuse, and that didn't help. The fusible links on the positive battery cable look OK.

The next thing to look for would be a broken wire in the group that goes to the plug-in connector to the alternator. Anyone know the best continutity checks for those wires?

90 GP · 08-06-2011, 07:02 PM

One of those fusible link on the positive cable is for the alternator. Remove positive cable and check the link/links for continuity. If you have to replace one the plastic cover on the bottom and top pivot to be able to access screws/nut to remove it.

***REN69*** · 08-06-2011, 11:17 PM

Bosch... that's all you had to say, if it's the same as everything Bosch, their parts never seem to work properly on japanese cars.

tashirosgt · 08-07-2011, 12:56 AM

The first new Bosch alternator tested good at O'Reilly.

I've never been able to pull out those fusible link thingy's on the positive battery terminal. Is it simply a matter of using a lot of force? The copper inside them looks OK.

I just noticed that one wire is broken off the plug-in connector to the alternator! And it's broken off close to the connector. Is it possible to buy a new connector of that type?

(I'm not sure if the broken wire solves the problem since it might have been broken in one of the two alternator changes that I did after this problem began. Nevertheless, it must be fixed and I'll hope that is the answer.)

tashirosgt · 08-07-2011, 01:06 AM

I found this connector sales place: http://www.repairconnector.com/categ...OR-CONNECTORS/

Anyone ever dealt with them?

90 GP · 08-07-2011, 04:33 AM

The fusible links are secured in place by a small hex shaped screw on each side that secures each wire lug to it. The bottom of the fusible link holder opens up so you can remove the screws and extract it.

tashirosgt · 08-07-2011, 11:22 AM

Thank you for that info, 90 GP! You have solved one of the great autmotive mysteries in my life.

SuperRA · 08-08-2011, 01:33 AM

Quote:

Originally Posted by tashirosgt

Thank you for that info, 90 GP! You have solved one of the great autmotive mysteries in my life.

Does this mean the problem is fixed? Either way, you might want to click 90GP's little "thanks" button to say thanks.

tashirosgt · 08-08-2011, 12:19 PM

I was thanking 90 GP for explaining how to get the fusible links out.

For the record: The problem of the charging system was fixed by repairing a broken wire. It was broken off too close to the old connector to use a splice. I used the alternator connector off of an old engine and put it on the harness with crimp-on wire splices. The alternator connector has a thick white wire with green stripe (10 gauge), a black wire and a brown-and-black wire. The black wire was broken. The symptom this caused was that the voltage across the battery terminal with the engine idling read only about 12.3 volts, which was just the battery voltage. After the repair, it reads about 14 volts.

I find it hard to get crimp-on splices to hold. I used "bullet splices" on the thin wires. The male ends go on with no problem. It's hard for me to tell when I've gotten the female ends properly crimped, but I'm not using a special tool, if there is one. For the 10 gauge wire, I only found the single piece type of connector for sale.