: Alternator Question

12-10-12, 03:01 PM
I have a 99 Catera and the voltage guage reads just below the half way mark. When I out the rear defroster on the needle drops to almost the red zone. I have been havinh problems with the battery dyeing after driving the car on short trips, so I presume the alternator is going.

I will check the free stuff first, but I am sure I need an alternator. I know there are different brands of alternators available but would parts from one fit another?

I want to get a rebuild kit but I do not know the brand already in the car (original?). Also, is there a diode in this alternator or is that old technology? I am asking because a rebuilt kit I saw comes with bearings and a voltage regulator/brushes. I used to replace the diode when rebuilding alternators, but that was years ago.

Thanks for the info,

12-10-12, 11:09 PM
I had problems of the battery dying intermittantly and right after driving it sometimes. Long story short, it was a bad positive battery cable. See if there are any brown sections on the cable and if the cable is frayed at the battery connector. Worth a look.

12-11-12, 11:16 AM
Same here bad positive terminal. Doesn't look like it made very good

12-15-12, 10:46 AM
You are obviously in my age cohort. I also remember the isolation diode as the first check after the battery when having charging problems. I doubt if modern autos are equipped with said diode, but I've always been baffled by electricity. I would recommend trying the Omega Owners site, but I keep getting banned from using it without any apparent reason. In Europe, these cars are more plentiful and those Englishmen are very resourceful about keeping them on the road and posting easy pictures to allow follow along repair. Knock on wood, but I have only had the intermittent door lock problem in the electricity department. The alternator is probably fun to change, yes?

01-06-13, 12:33 AM
my 97 would do the same, as long as I didnt turn everything on gauge would stay at 12V, as soon as I turn lights, heater, defoster on it would drop to almost 10V, so I replace the ground terminal and clean the pos-terminal and still the same so i bought a 140amp alternator on e-bay and install it, now the gauge only drops to 11.5V when everything is on, when everything is off 12.5, FIX ;-)

12-19-13, 02:27 PM
I thought I would update this post. My Catera sat for most of the summer because I needed my van for work. Today I added a cable from the alternator
to the battery and the electrical problem went away.

I ran the car with the climate control on, the rear defroster on and the headlights on. The volt meter needle moved a small bit, which is normal, nothing like it did before.


12-19-13, 04:12 PM
Thanks for the update. My gauge reads barely 12 Volts most of the time. I'll check out the Positive cable soon. It would go a long way to explain some of the electrical gremlins who live in my Catera.

12-19-13, 04:37 PM
I checked the output at the alternator (at idle) and I was getting 13.7 volts. At the battery, I was getting 12.7, that's a big difference.

I took an old jumper cable and used one cable from it and put on a couple of crimp-on terminals and added it to the alternator.