Interesting discovery about non-functioning information cluster
 

So last week my alternator gave out on me, or so I thought. I went to O'reilly's and we did the on car test, and sure enough, it's got low output. So I go home, since I have to wait a couple days for the part to get here. Well it finally arrives, and so I change my alternator before I pick up the new one so I don't have to pay the core. Well when I get the old alt off, there is a 2-wire plugin just hanging out behind the alternator. Thats wierd, I thought, but that was all I thought. So my wife goes and gets my new alternator for me, as I have to go to work. So when I get home and go to put the new one on, I realize that there is a plug in on the back of the alternator for the aforementioned wire. So I plug it in, and hook the alt back up and get it all back togethor. So when I go to start my car, before I turn it on, I notice that my dummy lights all switched on like they are supposed to. This has not happened for as long as I've owned the car. So now I don't think I needed a new alternator afterall, those wires just needed to be plugged in, and oreillys already sent my core out, so I can't swap it back out.

Summary- I thought my alternator went out, but it turns out it may not have gone out and instead just needed those two wires plugged in. As a side effect, my information cluster was nonfunctional. Now if only I could get the clock to work...

Clocks usually suffer from poor solder joints. Just pop it out and replace the solder. Hell, i've had good luck just reheating/reseating the existing solder and usually they'll spring to life. That connector on the back is used to power the field so the alt can start generating, however I think some 'self power' once rev'd up past a certain point. It also has a return that will trigger the idiot lights via the CPU.

yup that sounds abot right, since according to my volt gauge it would sit at like 10v until I had revved to about 3k. So which joints do I need to resodder to get my clock to work?

as an aside, just how accurate is the voltmeter in the car? It says 12v when the car is running, which isn't right, and my only other voltmeter says the battery with the car off is at 15v, so I can't tell how accurate the one on the car is.

Usually mine's been somewhat decent, it typically is around 13.5-14 (from guesstimating it's position) during running. 12v would seem a tick off to me, usually they're a bit more accurate than that. Only way to know for sure would be a multimeter. 15v without the alt charging seems even a bit high for a reading though.

Typically I resolder all the connections on the clock's display and anything else that looks suspect and it fixes it.

If you have an S5, all of the idiot lights suddenly coming on are indicative of a possible failing alternator.

Both S4 and S5 are supposed to do this, though often the S4 CPU doesn't work and won't trigger the relay. I think what he was referring to was that the connector on his alt was disconnected, and when he connected it to his new alt he finally saw that the lights work like they're supposed to.

exactly. I chased that problem for a long time before I finally gaveup. It's an S4, btw.

I'd say if they tested it and it came up bad, it was bad. having the connector unplugged prob had multiple side effects, not sure if toasting your alt over time is one of them. everything working OK now with the new alt (and the connector plugged in)?

BTW, I had some time to kill over the holidays and did the resolder trick on my cluster. all works again... for now :)

with the exception of my OEM voltmeter gauge possibly noy showing the right voltage, everything works good now.

sorry for the double post, my phone convinced me my first reply didn't work...