worb4me Posted July 26, 2016 Report Share Posted July 26, 2016 I did inadvertently hit a big puddle earlier today. Not sure if that caused the problem. 1998 Grand Prix GT. Been running well. So after turning car off after driving in all that rain, I notice a whining especially when giving gas from a stop. Dies down with rpms, but always seems to be there. Alternator bearing/s? Then later on trac off lamp flickers on twice, then stays on, then ABS, battery icon, SRS and I think another lamp come on. Fan, set at max, blows much less. I turn car off and it won‘t start. Haven't checked voltages or anything yet. I suppose I could walk the alt over to advance. Just wondering what you guys think. Quote Link to comment Share on other sites More sharing options...
worb4me Posted July 28, 2016 Author Report Share Posted July 28, 2016 right, and furthermore I replaced the alternator, and still have the problem of no charging or low charging. Got to get to the bottom of this. The bus driver suggested it's the battery itself, but that doesn't explain why the alternator isn't putting out 13, 14..vdc. The battery couldn't be pulling the whole charging circuit down, don't think. Something got wet maybe. Or something came loose. A short in a starter can drain a battery, while the car isn't running, but not sure if that has a thing to do with it. Battery was charged at advanced. They say it charged up to 12.9, but only 530 cca. Battery is rated for 630/750 or something. Granted the battery could be on it's last legs, but wouldn't pull down the charging capability of the alt. I did start the car, the meter read 11.87vdc after only a minute, slightly less at the alt itself. Not charging. Quote Link to comment Share on other sites More sharing options...
Nas Escobar Posted July 29, 2016 Report Share Posted July 29, 2016 check the starter. Quote Link to comment Share on other sites More sharing options...
worb4me Posted August 12, 2016 Author Report Share Posted August 12, 2016 What exactly am I checking? Car starts, just giving out wrong volts at alt. 11.8 maybe. I'll look underneath some tonight. Getting the starter out of this car doesn't look like cake exactly, if it's even required, from oogling the Haynes manual. Quote Link to comment Share on other sites More sharing options...
Nas Escobar Posted August 13, 2016 Report Share Posted August 13, 2016 I was thinking that it was the starter that was draining down your voltage for some reason. Maybe a bad solenoid or something. That would require you to take it to the parts store of course. If you have a new alternator, it should have a charge, unless you have a bad new alternator with a bad diode. Then again if you hit a puddle, it shouldn't flow all the way up to the top of the hood and splash. Your alternator should be at the top, not the bottom. On a W, only the LQ1 and maybe the Shortstar (never had one, so IDK) would have em towards the bottom. Anyways, it wouldn't hurt to check your grounds as well. Quote Link to comment Share on other sites More sharing options...
worb4me Posted August 13, 2016 Author Report Share Posted August 13, 2016 Well there's a fusible link, several associated fuses and relays. The battery could actually be the culprate. I have to get under and look everything over. Usually, I think, the starter will drain a battery when the car is off. Had that problem in my old Chevy van years ago. Quote Link to comment Share on other sites More sharing options...
worb4me Posted September 10, 2016 Author Report Share Posted September 10, 2016 Just an update (damn I‘m slow). Started the car at a friend's behest. It started fine, but voltage across battery was 11.67vdc or something. I revved the engine, no change. Alternator is officially doing nothing, as far as I can tell. Still haven't jacked it up and looked at grounds (doubt that's the problem), or the fusible link or whatever. And battery is a brand new Bosch. Quote Link to comment Share on other sites More sharing options...
gmcem50 Posted September 10, 2016 Report Share Posted September 10, 2016 In the last four months, I've had two Bosch batteries take a dump. Both were less than a year old. One was in a daily driver and the other was in a car that gets driven maybe once a week. Both just suddenly went down to +/-10vdc for no reason. I got both replaced under warranty, but damn... Quote Link to comment Share on other sites More sharing options...
worb4me Posted September 10, 2016 Author Report Share Posted September 10, 2016 Well it also ain't the fusible link, an ohms reading between alternator stud and positive battery terminal (with negative disconnected) was 0.00 ohms. So I guess it's either grounds, the pcm, or bad reman alt. I still don't know what the pcm puts out or how to check it. Anyone? Quote Link to comment Share on other sites More sharing options...
Padgett Posted September 10, 2016 Report Share Posted September 10, 2016 Have seen the ICM on a 3.1 low on the front also. That said, first I'd disconnect the battery completely to clear everything, then start and see what happens. Also check the ABS wiring at each wheel. I have seen hitting a deep puddle at speed rip all kinds of soft things apart. Water is hard. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted September 10, 2016 Report Share Posted September 10, 2016 the PCM should contain a switched 470 ohm resistor that's used to switch on the alternator, if you feel like pulling a wire out of the harness(small red wire either at the B terminal of the alternator connector or pin 61 of connector 2 on the PCM), you could emulate that with either a similar value resistor(if 1/4 watt, use for a very short period of time, 1/2 watt will be fine for continuous use but will get hot) or a small bulb(like a 194, or something in the .5 to 1 watt range anyways) to see if you can get the alternator to kick on. if you directly connect it to +12V, you will destroy the regulator. I kind of doubt it based on how it's operating, but it's a cheap/easy thing to rule out. Quote Link to comment Share on other sites More sharing options...
worb4me Posted September 10, 2016 Author Report Share Posted September 10, 2016 So where do I get specific info on the pcm? Join all data? What does the abs wiring have to do with any of this? I had thought the problem was narrowed down to the pcm or wiring/corrosion issues at this point? Am I not allowing for something else? Quote Link to comment Share on other sites More sharing options...
Schurkey Posted September 11, 2016 Report Share Posted September 11, 2016 Well it also ain't the fusible link, an ohms reading between alternator stud and positive battery terminal (with negative disconnected) was 0.00 ohms. A heavy cable like that CANNOT be properly tested with an ordinary ohmmeter. The cable is made up of stranded wires, half the wires could be broken and the cable would still pass the tiny current of an ohmmeter. Testing that cable properly will require a voltage-drop test, and a VD test won't be accurate without the alternator producing current--in fact, the alternator should be producing near-maximum current while the voltage drop is being tested. You need to test both the + side, from alternator output stud to battery +, and the negative side, from alternator case to battery negative. Quote Link to comment Share on other sites More sharing options...
worb4me Posted September 12, 2016 Author Report Share Posted September 12, 2016 ok so to ascertain the integrity of the cable and fusible link, a vd test is necessary. but alternator has to be putting out near maximum current. Not going to happen unless I can "full field" the alternator, iow bypassing so to speak the pcm. Now stil the pcm could be fine I guess, but it's not doing it's job for whatever reason. What would be the reason to conduct a vd test if the alternator was functioning correctly? And if the cable was compromised (half it's strands burned out or whatever) wouldn't the fusible link have gotten blasted before that happened? I'm just trying to take all this in. Revving the engine produces no additional voltage. Clearly the alternator is doing nothing, right? Quote Link to comment Share on other sites More sharing options...
Schurkey Posted September 12, 2016 Report Share Posted September 12, 2016 First Guess: Failed alternator Second Guess: Failed ECM, doesn't excite the alternator. (or is it the body module that controls the alternator?) Failed battery can drag system voltage down, but what you have seems too extreme for that. Possible, not likely. Checking VD on the starting/charging system is just good practice. The issue is less a matter of cable strands failing than connections corroding, although melted or frayed wiring is a possibility. Tensioner of the alternator belt (Serpentine?) working? Belt didn't fall off when it got wet? Quote Link to comment Share on other sites More sharing options...
worb4me Posted September 12, 2016 Author Report Share Posted September 12, 2016 Belt didn't fall off, friend seemed to think it had extra slack though. 11.67 vdc even when engine is revved. The pcm controls the altetnator. Problem is I don't know where to find specifics about what should happen on what pin when everything is working correctly. Do I have to join All-Data? That info can't be in the Haynes manual. Factory service manual? Could get it. Quote Link to comment Share on other sites More sharing options...
ron350 Posted September 13, 2016 Report Share Posted September 13, 2016 Never mind I am so confused. Imp558 1 Quote Link to comment Share on other sites More sharing options...
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