Alternator problem...

excelguru · #1 (**permalink**) 09-19-2002, 01:20 PM

Okay, here we go...

Upon initial startup this morning, the amp meter would immediately point WAY positive for about half a second, then point to zero (or slightly negative) for half a second, then back to WAY positive again for half a second, then back to near zero for half a second... this went on for about 10 seconds or so before the needle finally stopped jumping and came to rest at slightly negative. This is where the neelde stayed during my first test drive of the day.

After that short drive (maybe 2 miles), I turned off the car and checked to make sure that all the spark plug wires were seated securely in the distributor cap (I think one or more may have been loose). Then I cranked it for it's second test drive for the day.

During the second run (maybe 1 or 2 miles), the amp meter never read positive at all, only slightly negative the whole time.

I know the amp meter is working because I can turn on the cooling fans and watch the needle jump slightly more negative. I also know because the battery was as dead as a doornail yesterday evening and had to be charged all night. The wiring connections between the voltage regulator and the alternator are correct and tight. The connections between the alternator and the wiring harness are also correct and tight. I'm at a loss unless the alternator itself is bad (possible, but not probable). Any suggestions?

I won't be able to check this post much in the next day (and not at all over the weekend). So in addition to posting suggestions here (for others who may have this problem) please also give me a call at ... (cell phone).

Thanks guys!

Keith

Mr.Fixit · #2 (**permalink**) 09-19-2002, 02:31 PM

try swapping regulators.

bran3b · #3 (**permalink**) 09-19-2002, 02:58 PM

If it has an external regulator, check the ground to the regulator. I had problems until I ran a ground wire from the alternator body to the regulator.

agro1 · #4 (**permalink**) 09-19-2002, 03:03 PM

check voltage reg - it may be bad. Check red wire into voltage reg (mine was loose and thus fryed my alternator). Change alternator, the initial startup needle bouncing around thing may have fried it.

Monster · #5 (**permalink**) 09-19-2002, 08:41 PM

Keith,
All of the suggestion so far seem to be right on as the most likely cause of your problem. Some suggestions for isolating electrical problems.

1) grounds- check all grounds, make sure your engine is grounded, the regulator has a good ground etc. because of the design of these cars, the frame acts as the primary ground plane. A good heavy duty ground from the battery should be used to insure proper grounding......did I mention that the ground is important

2) Check all other electrical connections to insure that they are secure and clean

3) Check the voltage output of the alternator at the battery, with the engine off check the voltage at the battery it should read 12-12.5v nowwith the car running is should be approx. 13.5 - 14.5v.@2000rpm. Turn on the headlights and the voltage should drop and then recover.

4) If the voltage reading is greater than 15v the check the regulator ground, if it is ok the problem is Alt. or Reg. or wiring. If the Alt. is internally regulated replace the Atl. If it is externally regulated remove the connector and check the voltage at the abttery again with the engine running. If it dropps the regulator is bad. If the voltage remains high there may be a short in the wire between the Alt. and Reg. or there's a short in the rotor or stator in the Alt.Check the wire and if its OK change the Alt.

If the voltage is lower that 13v while running, a full field test can be performed which basically by-passes the regulatorand sends full voltage to the Alt. field (rotor). To perform this test (remote regulator only) disconnect the regulator connector and jumper between A and F terminals. If the output is normal during this test you know that the Alt. is good (bad Reg.) If the voltage is low the Alt. is bad.

(Test Information is from Haynes Techbook -Automotive electrical Manual)

note;If you are using an Optima or similar AGM (Acid Glass Matt) spiral design its important that the charge voltage does not exceed 14v and that you ONLY charge the battery at 1-2amps (trickle charge) over charging these batteries will cause them to fail.

Good luck hope some of this helps,
Mike "monster"

excelguru · #6 (**permalink**) 09-20-2002, 01:12 PM

Problem Solved!

First, thanks for all the feedback. My problems were as follows:

1. Engine wasn't grounded. (Does that qualify me for the dumbass award?)

2. Alternator was bad.

Luckily the regulator wasn't fried (it's a miracle). The original alternator was purchased from an Advanced Auto Parts store, so I just explained the situation (they know me by name now, anyway). It was no problem at all. Five minutes later I had a brand new alternator (which they tested before they gave it to me). I took it home, installed it, grounded the motor, and... tada! Everything worked!

Keith