Battery light pulse

[Spittybug]

I think this is a new development, but who really knows. While driving last night I noticed an occasional nanosecond-long flash coming from my idiot lights on the right side of the binnacle. It took me a while to actually see which light it was and it turned out to be the battery light. I couldn't correlate the minuscule flash with any actions (gear shift, engine rev, other loads, bumps....) and frankly, during the daylight one might not even see it, so I may have had this for a while.

The alternator is brand new as is the battery. No other ignition issues at all. I'm not overly worried at this point, but it does raise some questions. That light only goes on if either the battery or the alternator fail, thus allowing current to run through the lamp, correct? Suggestions? Anyone else get this?

[Regulus]

Hello,

I beleive I had a similar problem as you, might be worthwhile to see thread:

http://dmctalk.org/showthread.php?410-Electrical-Grounding

My Battery light pulse happened whenever the A/C Clutch disengaged. The problem wasn't so benign, as it eventually destroyed my Alternator regulator (in the Open position, so it sent 18+ volts to the battery!). May people advised me that it was probably a ground issue (which makes perfect sense), but I've added about 4 separate extra grounds to the compressor to no avail.

Anyway, I could be some electrical component switching off and momentarily dumping its charge back into the wiring loom. Something that draws a lot of current for a while, then de-energizes completely would be my guess (fans, compressor, etc...)

Hopefully, the matter can be solved by cleaning the major grounds.

[Spittybug]

I will see if I can correlate the compressor to the light. I read your thread and while similar, your light sounds like it was on for longer than mine....Mine is barely perceptible it is so quick. I have to agree it sounds like a momentary "pulse" associated with an electrical load change. Thanks.

[Bitsyncmaster]

There is a capacitor shown on the schematic attached to the AC compressor clutch wire. Wonder if that has anything to do with your flashing light problem.

[content22207]

That light only goes on if either the battery or the alternator fail, thus allowing current to run through the lamp, correct?

Or if a wire jacket between the dash and the alternator is compromised and shorting to ground.

Bill Robertson
#5939

[Spittybug]

There is a capacitor shown on the schematic attached to the AC compressor clutch wire. Wonder if that has anything to do with your flashing light problem.

I'll have to take a closer look at that. If it was integrated into one of the harnesses I removed (including the one to the A/C compressor) then you may have hit the nail on the head! If so, easy fix!

[Regulus]

There is a capacitor shown on the schematic attached to the AC compressor clutch wire. Wonder if that has anything to do with your flashing light problem.

Hello,

Could you supply me with some more details regarding this Capacitor? I cannot find it referenced anywhere, and I think it may hold the answer to my problem as well. Is it internal to the compressor itself? on somewhere on the wiring harness?

Thanks

[Bitsyncmaster]

Hello,

Could you supply me with some more details regarding this Capacitor? I cannot find it referenced anywhere, and I think it may hold the answer to my problem as well. Is it internal to the compressor itself? on somewhere on the wiring harness?

Thanks

Schematic shows it as a 0.5 uf (I think) hard to read. I cant say I have seen it but the circuit is a pink wire going to Compressor clutch, low pressure switch and the diode to the fan relay.

[David T]

If you don't use the car regularly it *could* be the alternator. There are brushes in it and the slip rings can oxidize and not make good contact momentarily causing the alternator to not charge. When that happens the voltage regulator will light the light. The other possibility is the oil pressure light. The wire going to the sender gets burnt up and momentarily grounds, flashing the light.
Check the belt on the alternator and put a sleeve on the wire to the oil sending unit on the rear left side of the motor.
David Teitelbaum

[Spittybug]

David T., while true that I don't drive it regularly, the alternator is brand new (<6 months) and I'm therefore reluctant to believe that is the culprit. I did manage to actually see the battery light flash ever so quickly, so I know it isn't the oil pressure light. All of the wiring in the engine compartment was upgraded in the last year and routed in such a way that nothing rubs. Anywhere that possibility exists, I used sheathing.

Do you know per chance the physical location of the capacitor that Dave M. pointed out on the schematic? If woven into the harness somewhere, I could have yanked it. Looking in my book and at the schematic, I believe it to not be part of the pink wire that runs to the compressor from the bulkhead connector. The low pressure switch is connected to the accummulator and the schematic indicates the capacitor lies between it and a ground point. I don't therefore believe I removed it. I would love to know where it is physically located however!

Dave M., any chance this could be related to the fan module issues that you and I have exchanged emails on? I'm seriously waiting for a break in this 100+ everyday weather to get out there and crawl over things. It's just not humanly possible when fluids are pouring out of every pore in your body........soon I hope.
:worship: Please let there be rain and some cooler temps soon!!

[Bitsyncmaster]

I have no clue where that capacitor is. We know it's not in the engine harness and not near the AC accumulator so my guess is it's near the mode switch. Has anyone got their center console out that can look for that capacitor?

Would not be hard to temporarily connect another capacitor to see if it cures your problem.


Dave M., any chance this could be related to the fan module issues that you and I have exchanged emails on? I'm seriously waiting for a break in this 100+ everyday weather to get out there and crawl over things. It's just not humanly possible when fluids are pouring out of every pore in your body........soon I hope.
:worship: Please let there be rain and some cooler temps soon!!

I think your fan problem is those 3 mm round connectors up near your washer bottle.

I just looked at that 2 pin 3 mm round pin connector I cut off my fuel pump and the pins have no pressure to make contact when they are mated. What I think has to be done with those pins is space the male pin a little (so the diameter is larger). But to do that you really need to pull the pin which is really hard to do.

[jawn101]

This sounds a *lot* like the issue I was having, but I still haven't tracked it down. A lot of good info was posted in my thread here: http://dmctalk.org/showthread.php?858-Battery-light-flickering

John just gave my alternator a once-over and said everything is cool. I don't really know what to do next either, so I'll watch this thread as well and maybe there will be other ideas :)

Good luck!

[David T]

I don't think it has anything to do with a capacitor. You could check all of your "big" connections on the battery, starter, frame, and alternator to make sure they are all clean and tight. If the car is used infrequently all kinds of gremlins pop up and disappear. If it goes away maybe it won't come back? I suggest using a Battery Tender to keep the battery fully charged so the alternator doesn't have to work so hard. Put it on 1 day each month and the day before you plan to use the car.
David Teitelbaum

[Spittybug]

I think your fan problem is those 3 mm round connectors up near your washer bottle.

I just looked at that 2 pin 3 mm round pin connector I cut off my fuel pump and the pins have no pressure to make contact when they are mated. What I think has to be done with those pins is space the male pin a little (so the diameter is larger). But to do that you really need to pull the pin which is really hard to do.

I think you may be right about this Dave..... I'm so very close to just replacing that connector with a good new one. Always easier to diagnose things if you eliminate the potentially intermittent issues.

[Bitsyncmaster]

I think you may be right about this Dave..... I'm so very close to just replacing that connector with a good new one. Always easier to diagnose things if you eliminate the potentially intermittent issues.

From what I've seen with those 3 mm round pin bullet pins.....I'm thinking the same (replace them all). Extracting the pins is almost impossible (very poor pin design) so I want to just cut them off and install new housings and pins.

[Bitsyncmaster]

If you can pull the male pin. Use a very small jewelers screw drive to open the seam with a gap of about 0.025" and then the pin holds very tight into the female pin.

With the screw driver, insert it into the seam and twist is sideways until the gap holds where you want it.

Now if I can just get a pin extractor made that will work on these pins.:mad1:

[Spittybug]

I just got home from helping Lazabby get his car started... he'll add to his thread separately, but I collected more symptoms of my battery light flash issue on the ride home in the dark.

I noticed on more than one occasion that the voltage dipped to 13 volts for a second or two immediately after the flash. Never lower though and not enough to dim the headlights. AC blower changed pitch a little too. Definitely seems to be related to something switching on or off, so a safe bet says it is cooling fan related. Dave M., I also got some strange fan fail light flashing near the end of the ride too, so I'm going to bite the bullet and replace the suspect connector in the front left corner of the car by the windshield washer bucket. I'm just going to clip all the wires and put on a new Molex connector (soldering all the pins, not crimping). We'll see if that does it. The fans are new Toby fans and both the fan relay and fan fail relay are Dave M.'s which have not been having issues elsewhere. All grounds are good as far as I know; I've cleaned them all fairly recently.
I don't know if it is related and I didn't want to risk any further damage, but I noticed my Alpine head unit behaved a little strangely too. I had a couple of very brief dropouts and one occasion where I got a bit of a volume "burst". I decided just to shut it off instead of using it to diagnose issues. If I've got a voltage spike/drop going on, that can't be good for it I'm sure.
I wish the weather would cool a bit; chasing gremlins is tough in this heat!

[Bitsyncmaster]

I just got home from helping Lazabby get his car started... he'll add to his thread separately, but I collected more symptoms of my battery light flash issue on the ride home in the dark.

I noticed on more than one occasion that the voltage dipped to 13 volts for a second or two immediately after the flash. Never lower though and not enough to dim the headlights. AC blower changed pitch a little too. Definitely seems to be related to something switching on or off, so a safe bet says it is cooling fan related. Dave M., I also got some strange fan fail light flashing near the end of the ride too, so I'm going to bite the bullet and replace the suspect connector in the front left corner of the car by the windshield washer bucket. I'm just going to clip all the wires and put on a new Molex connector (soldering all the pins, not crimping). We'll see if that does it. The fans are new Toby fans and both the fan relay and fan fail relay are Dave M.'s which have not been having issues elsewhere. All grounds are good as far as I know; I've cleaned them all fairly recently.
I don't know if it is related and I didn't want to risk any further damage, but I noticed my Alpine head unit behaved a little strangely too. I had a couple of very brief dropouts and one occasion where I got a bit of a volume "burst". I decided just to shut it off instead of using it to diagnose issues. If I've got a voltage spike/drop going on, that can't be good for it I'm sure.
I wish the weather would cool a bit; chasing gremlins is tough in this heat!

From my examination of those 3 mm round pins used in our car.....they don't have enough (any) tension to hold a good connection between them. I think you can fix them by pulling the male pin and using a pointed (sharp) screwdriver, space the pin at the seam. You don't much space to make the pin tight fitting.

[TTait]

Mine was tied to the AC compressor shutting off. Dave instructed me to install a capacitor and a diode from the pink withe on the compressor to ground, and it works very well.

See this thread...

http://dmctalk.org/showthread.php?410-Electrical-Grounding/page5

I know this is a solution that addresses the symptom more than the cause, but its pulling the spikes out of the system effectively.

I've ordered new ground cable kits from Hervey, but he seems to have disappeared. I have tried for the last week to get a hold of him - hope he's well.

Tom

[Ron]

I know this is a solution that addresses the symptom more than the cause, but its pulling the spikes out of the system effectively.
Did you ever check the Diode in the fuse compartment (between Otterstat and Fan Relay)?

The more I look at it, the more it makes sense for it to be the problem, especially since I can't see what other purpose it would have...
Also, if it is the problem, it is shorted out....if it burns on out, you'll overheat.
Maybe worth another look...

[Spittybug]

The problem seems to worsen. The blips are more pronounced and as mentioned before, are audible on the radio too. The radio is a symptom, not a cause as I get the problem with the radio off too. I really have a hard time correlating it to a fan or compressor engagement.

I have a couple of 12v regulators protecting LED lights. They've been there long before these issues, and I can't see how they would affect anything. http://www.radioshack.com/product/index.jsp?productId=2062600

I also have a 5v circuit to power the USB ports (unloaded though). I think this one is getting unplugged for some diagnosis just in case....... http://www.radioshack.com/product/index.jsp?productId=2062599

I can't really believe that it's a short circuit because of how quickly it flashes and the fact that nothing stops working.

Frustrating. The weather is now bearable, so I think I'll go check those diodes in the fuse bay.

[Spittybug]

Making some diagnostic progress. I removed Bitsyncmaster's fan module and put the old relay back in so that I could hear the "click" and also to have the fans come on and off with the A/C cycling. ~20% of the time, when the relay opens and the fans turn off, I get the battery light flash. Not with the fans turning on. I did not see it flash without the fans shutting off.

So I still can't tell if it is the compressor shutting off or the fans that is the culprit... Aren't capacitors supposed to "soak up" spikes like this? If I had a bad diode, things would be all screwy, not instantaneous blips, would't they?
:confused0:

[Spittybug]

Both diodes in the fuse area test fine; one way continuity only. :reading:
Now dissecting old harness to make sure there wasn't something within it that needed to be there.....

Does anyone know where the capacitor (#91 on schematic) that connects to the pink wire somewhere between the compressor and the low pressure switch is physically located? It does not appear to be at the switch, nor was it in the engine bay harness. By reading references to the other thread, TTait looks like he solved his problem by adding in a functionally equivalent capacitor. Is there a test that can be performed to see if this is the issue??

[Bitsyncmaster]

The fix for the compressor turning off causing his flash was to install a diode and another capacitor on the compressor clutch line. Diode and capacitor are wired in parallel with the anode side of the diode to ground.

[Spittybug]

This guy http://www.radioshack.com/product/index.jsp?productId=2062578 (3 amp, 200V) and this guy http://www.radioshack.com/product/index.jsp?productId=2062378&filterName=Type&filterValue=Electrolytic+capacitors (1mfd, 50V)?

In parallel, from pink compressor wire to ground, right?

[Spittybug]

Capacitor and diode in place and it looks encouraging. I test ran for 5 minutes or so and not a single flash. I even manually turned the A/C on and off to get more samples.

I may have discovered a culprit, but I don't know for sure. The red pigtail wire out of the compressor ends in a bullet connector in my car. This connects to my new wiring back to the bulkhead connectors. The bullet connection hides cleanly in one of the compressor housing holes on the top. It is possible that it could have intermittently shorted to the compressor housing since I could see a bit of the aluminum conductor that wasn't fully covered by the plastic insulation, like the bullet wasn't quite pushed in far enough. If that was the case, that might also explain why it sometimes seemed to cycle frequently; shorting the pink wire, disengaging clutch? I think I will leave the capacitor and diode in place as yet another "mod" in any case. Wow I hope this is the cure.

[Bitsyncmaster]

Inductive kick when you switch off a coil of wire (inside the clutch) can do lots of funny things. I guess that kick gets into the voltage regulator. The diode is the normal cure but adding the capacitor further helps.

Normally I would think a short circuit (compressor grounded clutch) would blow a fuse. But the use of 18 AWG wire used in our cars with 20 amp (or more) fuses does not always pop the fuse. One known example is the WUR heater that shorts.

FYI:
A fuse does not normally pop until you draw about 20% greater than the rating. It's all a time dependent thing when running the fuse near the rated current.

[TTait]

The Dave Mod seems to be fine in my car after - how long? check the dates on the posts...

off topic, but now how do I get ignition noise out of the am radio?

T

[Andrew]

This issue has reared its head on 5052. Through diagnostic testing I have isolated the issue to a voltage spike the compressor clutch when it disengages. I've picked up the diode and the capacitor at my local electronics store. Could somebody who has done this mod post a picture or two of the setup just so I have a point of reference?

Thanks!

[Bitsyncmaster]

I used a zener but pretty sure a standard diode will work. Wire the diode side with the bar or pointed end to the compressor. Other end to the compressor case.

[FABombjoy]

I've picked up the diode and the capacitor at my local electronics store.
That's funny, I don't remember you visiting my house ;)

[Andrew]

I used a zener but pretty sure a standard diode will work. Wire the diode side with the bar or pointed end to the compressor. Other end to the compressor case.

Thanks Dave! So the capacitor is situated between the power feed and the coil and the diode is wired in parallel with the bar side to the compressor power line and the other side to ground.

[Andrew]

That's funny, I don't remember you visiting my house ;)

LOL! I actually went to Fulton Electronics on South Penn. I've gotten everything from TV antenna supplies to fuses for my pinball machine there. The staff there is 1000x more knowledgeable than the folks at my local Radio Shack were (back when they still existed)

By the way, one of these days I need to get your torsion bar adjustment gig back over to you. :-)

[Bitsyncmaster]

Thanks Dave! So the capacitor is situated between the power feed and the coil and the diode is wired in parallel with the bar side to the compressor power line and the other side to ground.

Correct on the diode. Capacitor would also be wired in parallel if you still want to use it. I don't think the cap will help anything. The measurement I got on my oscilloscope was a 200 volt negative spike when the compressor switched off.

[Andrew]

I installed the diode about an hour ago. The entire mod took less than 5 minutes. Following the mod I took the car for a test drive and confirmed that the problem is gone. I'm certainly not an electrical engineer, so I can't say how / why the mod works, but I'm happy that it does. Thanks to Dave for your help!

[Bitsyncmaster]

I installed the diode about an hour ago. The entire mod took less than 5 minutes. Following the mod I took the car for a test drive and confirmed that the problem is gone. I'm certainly not an electrical engineer, so I can't say how / why the mod works, but I'm happy that it does. Thanks to Dave for your help!

The problem is that negative voltage makes a ground noise. There have been a few alternators show problems with that noise. My problem was an electronic circuit I added would reset the micro from that ground noise.

What the diode does is absorb that energy from the negative voltage pulse so it does not turn into ground noise.

[BABIS]

would likely prevent the chance of these negative spikes having the compressor controlled by a relay?

[Bitsyncmaster]

would likely prevent the chance of these negative spikes having the compressor controlled by a relay?

A standard relay would not make much difference. My solid state relay would help since I reduce the speed of the turn on and turn off currents of the outputs.

What makes the noise in inductors turning off is the magnetic field collapsing over the wire windings. It works like a generator. So if you can reduce the speed of that field collapsing, then the generated voltage is reduced.