scottmoyer

This will be long, so grab a drink and get comfy....

I've noticed over the past couple years that my volt gauge fluctuates with the turn signal. Never really paid much attention, but thought that might help troubleshoot.

I took the car on the Hot Rod Power Tour and noticed the volt gauge drop down to about 11V. Pulled into a shop, they replaced the battery for diagnostics, tested the alt and said it was bad. They put my battery back in and replaced the alt with an Advance P786611 alternator. I've verified that it crosses to a 105Amp unit, so that should be good. Note...Still had the voltage fluctuation with the turn signal.

I drove about 1500 miles on this alternator and the voltage dropped down to about 10V while driving. I had no AC during this trip so that wasn't a draw on the system. I took the new alt back to Advance and they tested it good. They tested my original and it was deemed faulty, so it must've been diagnosed correctly on the power tour.

I started testing this in my garage and started the car, turned on the new, rebuilt AC, headlights, hazard lights, car in reverse with brakes on, etc. I got a 10v reading on the gauge. I removed the gauge and put a VOM in it's place and ran the same test. It was reading about 12.5v on the digital readout. I put the gauge back in and it registered about 10V. Sounds like a faulty gauge.

I ordered a new gauge, installed it and ran some tests. The gauge was reading just under 13V with all of the same load and it does not fluctuate with the turn signal. Problem solved! Or so I thought!

I drove the car this weekend and noticed the voltage dropping while driving. I had the radio on, AC on max, and turned my headlights on due to darkness setting in. By the time I got home, the new gauge was reading about 11V. Here's the new kicker, the turn signals were flashing about half the speed of normal. I didn't check the windows to see how slow they run.

The voltage at the battery has always been 12.5V or above during all of the tests and even this weekend with the slow turn signals. Does anybody have any advice on this? I searched the forums for this and see that many have experienced similar issues, but I have not been able to find a resolution. Is it the alt again? Thanks

scottmoyer

Sooooo. Like all of the other posts I found, nobody has any fixes for this issue? If I find one, I'll let everybody know.

willk

iTrader: (1)

I recently fixed a similar problem with my '84. Have you checked your fender and firewall grounds under the hood?

majobis

iTrader: (3)

Have you been able to locate the problem yet?

Last Saturday, I bought a brand new alternator and prior to installing it, I charged the battery up and additionally used electronic contact spray and a wire brush to clean all battery and alternator related cables. The alternator was installed on Sunday and the car started right up. I then let it idle for 10 minutes and noticed that the voltage gauge stayed in its new favorite place - the red zone.

On Thursday, I drove the car (started right up) to the alternator shop to have him double check the output. I shut it off, walked in and spoke with him and less than five minutes later, we walked outside with his tester. He told me to start the car. I tried, but only 'clicking' associated with a dead battery was heard. I double checked all my connections and they were good. He told me that he wanted to bench test the battery and alternator but that they needed to be out of the car and for insurance reasons, I couldn't do it in his lot. All he could tell me was that my battery was less than 10 volts at this time.

Five minutes later, I have a jump start and I'm driving home. I get less than a mile and the car starts going ballistic with power cutting out etc. The gauge was completely buried in the red. End result - a tow home.

Today, I brought the battery back to Autozone (it's their Duralast Gold which has a 3 year free replacement warranty) and got a brand new one from them. I then took the battery and my alternator (loose) to the alternator shop where the alternator tested at 14.5 and the battery at 12.5

I brought them home, installed them, double checked everything, started the car and drove around a bit. The car ran fine, but now, instead of the gauge being buried in the bottom of the red zone, it stays at the top of the red zone (below 8).

I considered a new gauge but wanted to check in with your progress first.

scottmoyer

I have not fixed the issue yet. I cleaned all grounds that I was able to locate. The main ground on the passenger side of the block has not been addressed due to access to it and the time to get at it. Maybe today. I have also discussed this with a local shop. My thought is that if the block ground doesn't resolve it, I'll take the car in and have the shop locate it and fix it. It might cost me some money, but if they don't fix what I pay to have them fix, I can keep taking it back until they do fix it at no additional cost. I'll be taking it in this week hopefully because there is a car show in two weeks that's about 1.5 hours away and I don't want to get stranded somewhere.

jermdm

I have the same issues with my iroc too. My volt gauge has always bounced around when using the turn signals and when driving, the gauge will read fine and other times it will read about 11 volts or so. The car can be idling and I will see the gauge bounce around sometimes for no reason at all. The gauge will also drop and come back up when I turn on the headlights and it will flicker when I hit the brake lights. I've pretty much figured this is normal since the gauges and the wiring in our cars arent the best. I have checked pretty much everything I can, Replacing the gauge, making sure I have good grounds on all that I have found and making new grounds with 4 gauge wire at the battery to the body and engine to the body. This made it a little better. My turn signals use to flash really slow but now they are fine since I replaced the battery and keep a battery tender on it when I'm not driving it. I would think that is a ground problem causing this issue with the volt gauge. I've never tried to track the problem down since I thought this was a normal condition, just like the gas gauge bouncing around from fuel slosh. I guess I'll have to try to track down the problem when I get a chance.

torque_is_good

I start with the basics

with vehicle off, measure battery voltage by simply measuring at the 2 leads


then, with vehicle running, measure the battery voltage. It should be higher reading 13 point something. Look at the wire running from the alternator to the positive block (near the radiator). Is the wire of very small gauge? If so, run a 2nd wire. The wire coming from the harness as it exits near the A/C and heads to the positive lug should be heavier gauge so you could always connect a secondary wire there using a wire nut.

majobis

iTrader: (3)

This car is killing me!!!!!

Since the above posts, I haven't driven the car in about a week. Today, it fired right up - but the volt gauge still stayed well under 8.

I drove it for about 20 minutes and shut it off for about an hour while doing errands. Then, I drove it another 10 minutes to another store. Afterward, the first turn of the key made a quick clicking sound. The second try, it started right up. I noticed then that the volt gauge was at the mid point of the red zone now and fearing another tow, I decided to drive it home.

About a mile from my house, the car started hesitating a bit. As soon as I got into my driveway, the car struggled to make it into the garage. In the garage, I kept it running while I grabbed my newly purchased multimeter. The battery reading made it up to 7 before the car shut itself off.

With all of the members on this site who all own at least 20 year old cars, I'm hoping we can get more feedback on this problem that can't really be this unique, can it?

firebird904

I have this problem in my 88 too. I hope someone find's what causes this as I am at a complete loss with this issue I think I'm going to purchase an autometer volt gauge to monitor and see if it could maybe be the wiring to the factory gauge.

To the OP that is a beautiful IROC you have

torque_is_good

have any of you bothered to check the wire that I mentioned? The darn thing is probably original and has corroded connectors or corroded wire. Do you have some old 14/2 or 14/3 household wire kicking around? if so, cut off a chunk and run a wire from the alternator output to the positive lug which is where the stock wire runs. I'm not saying that wire is your final fix but if your problem goes away, then you have found that the charging from the alternator is not properly recharging the battery because of the bad original wire.

it's basic troubleshooting guys. There is no need to try and trace the original wire, just bypass it per my suggestion

Jim85IROC

iTrader: (2)

In my experience, if this wire is faulty, it can (will) also ruin alternators. Scott, since you had one alternator crap already, this indeed could be your problem.

You can check this wire without bypassing it though. Measure the voltage at your battery with the car running, and measure it at the alternator terminal. Do this with a load (i.e. headlights on, ac on, etc). The two voltages should be the same within .10 volt or less. On my Corvette the voltage loss through that wire was only about .08, but after ruining 3 alternators, I parallel-wired a piece of 4 AWG wire to the original, and never lost another alternator.

However, I don't suspect that this is your problem. In the situations where I've found this wire to be inadequate, I didn't have the sort of symptoms that you are having, though I suspect if the problem is severe enough it could cause it.

firebird904

[quote=Jim85IROC;5051720
You can check this wire without bypassing it though. Measure the voltage at your battery with the car running, and measure it at the alternator terminal. Do this with a load (i.e. headlights on, ac on, etc). The two voltages should be the same within .10 volt or less.[/quote]


That's the first thing I did when I noticed the problem and it tested out fine even though the gauge was reading low.

scottmoyer

Same here.

Maverick H1L

iTrader: (8)

Have any of you tried checking the alternator plug for the proper volt readings? Should be 12V (battery) at the red, brown, and tan/white wires. Low volts on the brown and tan/white (90+ do not have the tan/white wire for some reason) indicate a problem. The red wire should be good as it comes straight off of the starter... Unless the fusible link blew.

At some point, I may have had a problem with the tan/white wire (at least that's what the guy at the truck shop said when he towed me there after the car died in a rest stop in PA), and the guy replaced it with a wire from a different circuit somewhere (forgot where)... Alt charged around 13.5V or so. I found where he cut the end of the tan wire to, replaced the section of wire between there and the alternator plug, and now I charge at 14.7 when the engine is running (and the regulator is good... I've had 2 of them go out now).

torque_is_good

and that is why I say to bypass it or add a 2nd wire. To any of you who have spent years working on things, especially items which are 20-30 years old have you run into something that didn't make sense but ended up being a fix?

Measuring is nice, you can't be certain until you replace the wire or add a secondary wire. The above example confirms that. These are 20-30 year old cars and most have original harnesses and some, God forbid have harnesses that were in junk yards and then re-used.

I can't say for certainty if the cable is your problem any more than you can say with certainty that it isn't.

Jim85IROC

iTrader: (2)

I added the wire because there was a measurable voltage drop between the battery and alternator. It wasn't quite the .1 volt drop that people specify as being "bad" but it was close. In other words, my measurement worked just fine.

For what it's worth, after adding the 4 AWG wire, my voltage drop was very low, to the order of .01 or .02 volt difference.

majobis

iTrader: (3)

Update: I replaced the main (4 gauge) battery negative wire with a 2 gauge wire. I also attached the small wire that came attached to the new negative battery cable to my front wheelwell metal.

I then replaced the 10 gauge alternator-to-battery cable with a 4 gauge wire.

I'll be installing a 2 gauge wire for my positive terminal too but I can't reach the block end so I'm awaiting either a lift or a low profile jack w/stands.

When I turned on the car, the gauge finally got out of the red zone, but just barely above where the red starts. Then, I ripped open the flexible black plastic conduit from the large harness near the battery and found all sorts of old splices from previous owners. My next project is to, at the very least, cut out the splices and redo them myself. I'll keep the updates coming and hopefully, someday, my gauge will be back in the middle where it was only a few months ago.

scottmoyer

Ok, here's my update.

I got tired of dinking around with this and decided to pay someone more knowledgeable than I am (not that hard). The shop had the car for a few days and verified all grounds. They tested the alternator output and kept chasing all options. They added a heavier wire to the alternator, already mentioned here, and didn't see any change. After all kinds of diagnostics, they tested the alternator output again and found the output at the alternator was at 10V when the dash gauge was reading 10V. If the engine was revved, the voltage would go up, but under full load, in gear and stopped, the voltage was dropping. I was told the alt is charging the battery as long as I'm driving. Unfortunately, I live in an area where there are plenty of stop lights and the chance of having the AC on full (Florida), lights on, turn signal on and even windshield wipers on (afternoon rains all summer), is very high.

I took the alt back to Advance and replaced it with another. I still have the same issue with this one. Sounds like these rebuilt alternators are all crap and the regulators aren't very good. I drove the car about 200 miles on Saturday with the AC off and TTops out and ran about 14V the entire drive. I plan on getting my alternator repaired by a reputable shop and see what happens then.

Jim, I'll try the parallel wire option myself and see what I get. Thanks

KamikazeIroccy

iTrader: (1)

Hmm, I see I'm not the only one having problems...Okay so my car is an 87 Iroc...The voltmeter gauge isn't no longer showing 13volts....Last week out of nowhere the car stop charging.
So being the guy I am, I bought a new alternator and battery. Still the same issue so I warrantied out my alternator cause I thought the extremely low battery b4 I bought my new battery killed the alternator and to no avail still same issue, NO CHARGE!
So as of now I am stumped, I've checked my connections and grounds, I do have a ground to the body and also to the alternator bracket. Please someone give me an idea of what to check next also I've taken out the TPI and made it carb but really that's irrelevant cause the car was charging just fine just a few weeks ago!

Also you say that there is a fusible link? Where is this located?

Maverick H1L

iTrader: (8)

The fusible link for the alternator comes straight off of the starter solenoid.

Check to make sure the connector is good and tight at the alternator, and then make sure each terminal is making good, tight contact with the ones in the regulator. Check the connector for proper volt readings at each terminal. If necessary, check to make sure that none of the wires is broken at the back of the connector (inside the rubber plug where they are joined to the terminals). Failing that, it may be time to peel open the harness and look for possible damage.

:edit: Can't say I blame the remans... Killed the first accidentally shorting out the BAT terminal on the back of it one too many times (killed the voltage regulator and it was overcharging, which is how my battery tray died). The second one had the voltage regulator going bad (undercharging, not low enough to kill the battery, but low) and the rectifier bridge finally went out one day, so I rebuilt it. Even though it had a lifetime warranty, I was forced to rebuild it because I couldn't afford another (no receipt due to special circumstance and the store conveniently had erased the alt from the computer).

KamikazeIroccy

iTrader: (1)

Thank You, will get on it tomorrow morning and let you know my result...My next culprit to check was going to be the the starter area cause everything up top seems to be fine connection wise!

1986tpiiroc

Hey Scott, I have an 86 IROC and I had those problems a long time ago. The gauge in the dash was always inaccurate, but my DVOM showed low voltage after vehicle was running for awhile. After about 5 Alts, all I believe were 108 Amps, I got a CS144 Alt out of I think was a 95 Buick roadmaster. Was rated at 140 Amps. Installed it and after even when hot I have 13.4 Volts with A/C and headlights running. Gauge in dash still sucks, but Alt is still perfect.

KamikazeIroccy

iTrader: (1)

What can cause the fusible link to go out?
Checked the alternator with voltmeter...wasn't putting out more than 12v took it back to parts store had them run it was putting out 14.86v on the machine so we ordered a new pigtail that plugs into the back the alternator. Won't be in to Tuesday though.

Maverick H1L

iTrader: (8)

Since the wire with the fusible link on it only goes between the starter and the alternator, there has to be some damage with the wiring harness, probably with the exhaust manifold, to kill the link.

KamikazeIroccy

iTrader: (1)

Wouldn't the car not start?
Maybe thats why when they plug their part at Orielys into the back of the alternator plug it showed 14.2v but when I measure on the car it was reading the alternator wasn't putting at any volts....I ordered a regulator pigtail anyway though...

majobis

iTrader: (3)

I FOUND SUCCESS!!!!!

I'm not sure if it had to do with the relays I replaced, but today, after doing so, my gauge finally went back to 13! Here's more info in another post I made: https://www.thirdgen.org/forums/elec...ml#post5065443

Maverick H1L

iTrader: (8)

I thought everyone knew that power on either the tan or brown wires at the regulator (pretty sure it's the brown one) came off of the coolant fan relay...

KamikazeIroccy

iTrader: (1)

Here's my issue, new battery new alternator checked out at 14.86v at the parts store not putting out any volts on my car though....checked fusible links its good, checked and replaced power wires and ground wire....bought a new regulator pigtail that plugs into the back of the alternator thought that would fix my problem since I figured that the alternator wasn't getting the cue to power on....STILL NO CHARGE and was forced to take off yesterday due to me breaking down omw to work.

So I need to check my coolant fan relay? The fan works and turns on perfectly
Any suggestions anyone? PLEASE HELP it's getting cold and I don't wanna have to ride my motorcycle that much longer
in advanced folks!

majobis

iTrader: (3)

Maverick H1L and KamikazeIroccy

Regarding the photos I posted, since I can only post three, I just chose various ones. All three of my relays had wire connection issues; the first photo was chosen simply because it was the worst relay I had. Regarding the package of brand new connectors I posted, I just chose a random photo. Three brand new ones were purchased. The third photo is just an example of how the new relay and connector will look together.

In summary, all three relay connectors had bad wiring and some of the bolt holes were broken on the relays, so all three relays and all three wire connectors were replaced. I don't know if one had to do with the other, but for some reason unknown to me, my volt gauge is back to normal which is fine with me after my recent problems. Let's hope it stays that way!

KamikazeIroccy

iTrader: (1)

I'll check my relays today? (My car isn't TPI anymore and has since got a correctly converted CARB system with holley regulator and all)
Thanks for the heads up I hope its that simple

Maverick H1L

iTrader: (8)

When the wiring degrades anywhere along the line, be it at a connector or elsewhere, the degradation creates resistance where there shouldn't be any. The resistance eats up the volts it takes for the current to pass through (let's say, it takes more power/energy for you to swim at 5 MPH than to jog/fast walk), so there is less volts available to power the voltage regulator and the rest of the alternator, so there is less charge to the battery. Even though I can't describe the position of the splice in the brown wire between the fan relay and the alternator (I think it may be either at or close to the relay), the same holds true. If the wiring is damaged at the relay (and it is with most of the older relays I have seen on our cars and similar vehicles since there is no weatherproofing back there other than the standard goop), then the relay requires more volts to be powered and there is less available for the alternator. Which is why a standard voltage drop test should be done between the FAN fuse and the alternator as a last resort if nothing else has worked yet. Which is also why I mentioned testing the voltage at the connector for the regulator.

majobis

iTrader: (3)

It's pouring here now, so I couldn't drive it beyond backing out of my garage just now for a minute, but when started it still went to 13 (whoo hoo!). This weekend though, I'll break out the new multimeter and grabbing readings as many places as I can. Thanks for the tips.

KamikazeIroccy

iTrader: (1)

Well I looked under the hood and I seen no brown wire that connects to the fan relay which is mounted on the side the radiator supper (drivers side). I'm half tempted to just give up and pay a shop

NINÅ

KamikazeIroccy

iTrader: (1)

Okay, sticking out the regulator is a red, black, and brown wire...They Wires all go into the weatherpack loom and on the cooling fan relay there is a black wire and greyish wired plus the reds.... ARGGGGGGHH

KamikazeIroccy

iTrader: (1)

Well fellows I finally figured out what it was...I did what you guys told me and test the brown wire with the key on, test light didn't come on so I traced the light all the way to the firewall, you know the wire harness all the way to the firewall.... well anyway the big connector on the side closest to the drivers side, yeah that wire harness was melted with plastic around it...The cooling fan wire still way hot with the key on so what should I do? Should I go to a junk yard to find another wire harness connect cut the wires then use connectors to hook the new one up or should I just cut the brown wire and run it to that cooling fan wire that was hot with the key on?
Thanks everyone

majobis

iTrader: (3)

Do you have photos? If you check this other thread I made, you'll see what parts I replaced-and one of them had a brown wire.

https://www.thirdgen.org/forums/elec...ml#post5065443

KamikazeIroccy

iTrader: (1)

It's none those relays its right by the brake booster

KamikazeIroccy

iTrader: (1)

Thanks Everyone the IROC is back rockin!

bjpotter

As to the original problem of low voltage, did any of the above solutions work? I have this problem. It started this fall. I start with proper voltage on dial but drops over time until it hits 10 - 11. My windshield wipers are slow and the blinker gets slow.

bjpotter

Alright, its 80 degrees out, sunny, and have no excuses now not to trouble shoot this problem.
My voltage reads fine on the dash when I start the car at 13 - 14. After 20 min it starts to drop until reaching 13 . If I am stopped with the brake on, it drops to 11 - 12. If I have a load on it (lights, heat blower) it drops to 10 - 11.
My symptoms are this. My lights dim and my turn signal slows down. Since I drive mainly on the hwy, my battery stays charged.
Electronics is not my favorite job, but I need to figure this out before I get stranded somewhere. After searching for answers here, I've come to somewhat of a plan.

1. Just bought a multimeter so I can check voltages at the battery and alternator. I had them checked last fall and they tested fine. I want to make sure this is not the problem.

2. Check and clean all the connectors, ground wires and battery cables. This seems to be where the majority of solutions come from. From the beginning I've thought it might be a grounding problem. I had similar types of problems with a previous car.

If that doesn't work I will need some help.

bjpotter

Went to part store and tested alt and battery again. Both tested fine. Put meter on it, 12.97 with car off, 14.01 when running.
I am now starting to clean the connections. Boy that ground from battery to block is in a fun place.