Hello! I need your help with an electrical gremlin in my FD. If you've followed my thread, you'll know I've gone thru a very lengthy 3 rotor conversion. Finally, it's all back together with the exception of an alternator/electrical issue which is keeping me off the road.

I am having a strange voltage issue with the car. Voltage is all over the place while driving. I have a Battery Bug installed on the car which allows me to monitor voltage. Took the car out yesterday after installing a new, 150 amp remanufactured alternator. Upon startup, voltage was over 14 and 13.8 with the AC on. So far so good. Drove the car at highway speeds for about 20 minutes and all was good until I noticed voltage dropping to 12.6. This was at 3,000 RPMs. Then noticed the parking brake warning light briefly flash a few times on the dash. Interesting. Pulled off the highway to get gas and when starting up the car, the dash warning lights stayed illuminated (battery, ABS, check coolant, fuel level) yet no warning beeping sounds. This continued for several minutes and they abruptly went off and returned to normal. Pulled in the garage, shut the car off, and then turned the ignition back on to see if the fans would come on. They did, but in the first ignition position, not the second which I believe is correct. Turned the ignition back off and then back on and this time, the fans came on with the correct second ignition position.

I should also point out that when I had an old, yet OEM (non-reman) alternator on the car I had no issues. In fact, I drove the car to DGRR and back (9 hours) without a hiccup. I then replaced this alternator with a stylish powder coated reman unit and started having issues. I replaced this one with the above mentioned 150 AMP unit and new gremlins have popped up.

Other info - I am running a 550 CCA battery which I had tested. Checked out great. New wiring to the battery. New starter also on the car. I'll go out to inspect the alternator harness this morning.

Please help solve this issue as it's the only thing holding me back from this year's Chris Carlisi Memorial BBQ!

 

you already know all this but the warning lights will come on when the alt output equals or falls below the batt voltage. checking the harness for the alt the pin tension and if the pins are clean would be a good place to start. when the car is not charging back probing the connector to see if it is getting voltage to turn on the alt could give you piece of mind as to wiring control.

do a voltage drop check ,if it is easy enough depending on your batt location, from the + post of the alt to the battery + when it is hot and running. also make sure the stud on the alt does not twist, this can be over-tightented when putting the cable on and cause some problems. of course do this with the neg disconnected lol. good luck. on a side note if everything checks out ok the alt may be bad. taking it to a shop that can check the alt in the car where you can see the diode pattern, amp output, and voltage on the car when it is hot would be a good option. i have seen several "rebuilt and good" alt just not work when hot.

 

As mentioned if the alt is not charging the battery those dash lights illuminate. Take the car out for a drive get it hot pull back into the driveway, turn on the wiper, headlights, basically all the accessories see if it dies or the idle struggles etc.... if it does I'm guessing you have a bad alt. I also suspect this because you mentioned it worked fine until you switched the alternator. With all the money you have invested I'd buy a NEW alt and call it day.

 

a lot of places have alternator testers. That's where I'd start.

 

Thanks for the feedback guys. I may not have made this clear in my original post but the current alternator in the car is a brand new (remanufactured) 150 amp unit I just got in on Friday. The reason I put this on in is the one that was on the car would barely make 12 volts at idle. This alternator blew out on me a few months back and was rebuilt again so I reinstalled it. Have never trusted it though hence the replacement unit installed on Friday.

I did find what I believe to be a suspect wire on the alternator clip so I just replaced that and am going out for a test drive now. We'll see

 

I have seen new alternator that were bad, so you might just want to ck it just in case.

Eddie

 

Seems you are correct sir. Found a suspect wire and fixed it. Started up the car, drove it to O-Reilly's and had them check it. Checked out fine - hmm.. Hung around a few minutes and the car heated up a bit. DING! DING! The warning lights came on and we checked the alternator again. This time - "Bad Diode":



So I am not sure it can be anything besides a bad alternator.

 

You Sir are correct...
After reading everything in your other post, the only logical answer thru process of elimination was the alternator. Your 1st alt was the only one you had NO issues with.. once you started changing them all your headaches started....

Glad to see you have made progress...

 

Spoke with the maker of the alternator and he is going to send a replacement ASAP. In the interim, I am going to check the alternator wiring to ensure everything is in good condition.

 

Most of the time you'll see this result - bad alternator. Glad you found it


Later

 

I got a new reman 150 A alternator a few years back and had the same problems. I wound up sending it back to have it repaired and it did the same thing again. I incorporated a 200 A circuit breaker in my system which would trip everytime I ran the car for 10 - 15 miles. Never could figure out why the alternator would not work in my car. The problem was with the diodes in the alternator, but other than that I couldnt find any problems. Once I put the OEM stock alternator in, everything functioned as it should. One other issue was that the battery was getting "cooked".

-chuck

 

Well, this is what the alt test showed on mine, a bad diode. We'll see with the new one later this week.

As an aside, I have posted this in my buildup thread. How about grounds on the car? Does it help to beef them up while I am waiting on the alternator? In particular, I am thinking about additional grounds on the battery which is relocated to the back passenger bin. How about a ground from the negative to the seat belt post? I've also been told you can ground it to a bolt in the driver's bin.

So I went ahead and ordered an HKS grounding kit and am planning on adding this to the stock grounds. Any advice outside of you could have made your own kit and saved the $$?