Corolla Alert - Alternator question....

[mikey]

I love this forum, even though my Tercel died a year ago, and perhaps there are enough similarities that someone can give me advice. It's a 1982 Corolla, and today the brake light and alternator lights came on simultaneously while I was driving, I topped off the brake fluid, and I do need to replace the front brake pads, but I'm not sure that's the problem. By the way, if I pull the parking brake lever, the brake warning light glows definitely brighter, and then dims when I release it. The battery voltage is about 12.8v, and stays about the same, or a little lower, when the engine is running. Turning the headlights on doesn't seem to make any difference. The repair guide I have says that the voltage should go up with the engine running. That's about the extent of my electrical knowledge, and the alternator is really hard to get at on this vehicle for further tests (or for replacement!) My experiences with Tercels was that the warning lights could do spooky things when the alternator was failing, but no knowledge about Corollas. Any Ideas?

[irowiki]

Yup, that indicates your alternator is bad, or maybe there's a connection issue.

[marlinh]

I would suggest going to a parts retailer and have them check the charging system for free.

[dlb]

the brake and battery lights usually point to alternator, and the 12.8V on the battery both when the engine is off AND when it's running is another indicator the alternator is not charging the battery. i like marlinh's suggestion to have it checked out just to confirm the alternator is bad though, just in case it's just a bad connection or something else simple.

[mikey]

I know it's not smart to just start replacing stuff at random, but O'Reilley's had an alternator for only thirty bucks, and I had been suspicious of the old one anyway. I swapped them, and no change at all. I've driven about thirty miles with the warning lights on now, and the battery is still charged. I also tried another battery, but also no change. Voltage regulator or some relay maybe? I'll try as many connections as I can find tomorrow.....

I think there's a fusible link in there somewhere.

[dlb]

an '82 corolla should have an external voltage regulator. probably very similar to the tercel's. i think there's a thread on here about checking voltage regulators so do a search for that and see if it's the problem.

[Petros]

does your alternator have an external voltage regulator? there is a simple test for it using a volt-ohm meter, check the service manual for test procedure for a the voltage regulator.

Other than that, check all fuses related to charging system. The condition of battery terminals and all the ground straps too.

[mikey]

Yep, it's external. Took a while to find it because it is solid state and doesn't look like a "normal" bathtub shaped brass colored one. Tomorrow I'll run some of the resistance tests found in a thread on this forum (thanks dlb) and any I find in Haynes and Chilton.

[mikey]

Update...problem solved.

The voltage regulator checked out OK, so I had to wait for the weekend to investigate further. I peeled all of the old oily electrical tape away from each bundle of wires in the area, and one by one pulled apart the connections and cleaned them. At the bottom of the mess was the biggest connector, containing the wires to the alternator itself. Sure enough, the thickest wire, the white one leading eventually back to the positive terminal on the battery, was corroded and had finally snapped, behind the connector and under its rubber boot. So I got 2 feet of similar gauge wire, and put round connectors on each end, the kind that fit over bolts, and bypassed the entire spaghetti bowl of wires completely. $6.00

Total cost about $40.00, because of the new alternator.