# Cant diagnose voltage drop issue



## snowwy66 (Nov 5, 2017)

You're diagnosing a normal routine. Although 11 is kind of low. 

Use an actual voltmeter and see it if reads different then the dash. They usually do.

Cars today don't put out a constant charge like yesterday's cars.


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## jimmyc (Jun 27, 2020)

I'm "old school"...in both the newer car knowledge and age. In the past, what you describe could be what was called a "voltage regulator"....usually located on the firewall....a black box with (sometimes) an adjustment screw. With these newer computer controlled cars, I have no idea if the CRUZE even has one or perhaps it is built into something else. (Wondering if your "current sensor" is another name for voltage regulator))


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## Blasirl (Mar 31, 2015)

RavenMartinez said:


> I've been trying to chase this electrical issue for months now. When I'm driving the screen shows anywhere from 11-15v depending on if I'm on the gas or not. When I'm at idle it slowly drops to 12 or below. The headlights and dome light also are dimming and flickering very bad, so much so that I'm not comfortable driving at night in it. I've replaced the alternator twice, as well as tested the mskt recent one, just tested the battery as well as cleaned the terminals and the ground point for the negative lead. I also just put a new current sensor just to be sure, but it did not improve anything.


Welcome Aboard!

Service Bulletin - NHTSA SB-10057574-8899
SB-10089945-2280
*How-To: Installation of the Big 3 Cruze Kit*
Clean the Terminals
Cruze Battery Upgrade Options 

don't forget to introduce yourself and your Cruze here.


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## RavenMartinez (Jun 4, 2021)

I understand the electrical system voltage varies while driving, and it's done it before when it was running normally, but currently it just drops and continues passed when the battery light comes on. The lowest I've seen it the last few weeks was 10.5 or so when I drove to work in the cold. Battery light stayed on. 

The voltage regpp0las far as I know is either in the alternator or the ECM, the current sensor is located wrappered around battery ground wire.


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## Thebigzeus (Dec 2, 2018)

Have you had the alternator tested?


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## RavenMartinez (Jun 4, 2021)

Thebigzeus said:


> Have you had the alternator tested?


Yea I replaced one, issue persisted, went to warranty the new one to get another replacement, they tested it and said it was fine, then tested the replacement and it was also fine.


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## Johnny B (Jun 4, 2019)

RavenMartinez said:


> The lowest I've seen it the last few weeks was 10.5 or so when I drove to work in the cold. Battery light stayed on.


You definitely have a problem, you should really never see the voltage go below about 12.5V -ish.

I just finished helping Ray with problem that has very similar symptoms. Please read through the post, the solution is near the end. I can help you also, but you need a multimeter.









BATTERY LIGHT


2011 Cruze 1.8 with only 49 thousand KM on it. The BATT light will come on while driving and it comes on with no predictable pattern to it. We changed the Alternator and Serpentine Belt and also the Battery, All the Grounds were checked and cleaned. All the Fuses and Relays have been...




www.cruzetalk.com


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## Thebigzeus (Dec 2, 2018)

Have you verified it at idle with a volt meter? To be sure it’s not just the ECM mis measuring.


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## RavenMartinez (Jun 4, 2021)

Johnny B said:


> You definitely have a problem, you should really never see the voltage go below about 12.5V -ish.
> 
> I just finished helping Ray with problem that has very similar symptoms. Please read through the post, the solution is near the end. I can help you also, but you need a multimeter.
> 
> ...



So I should start up next by measuring everything with a voltmeter I guess (Im not great at electrical so this will be a process lol) then check the contact points on my alternator and potentially running grounds from there to the body? Before I move on to the big 3 kit? The issues ray had seem similar to mine so hopefully I won't be on this wild goose chase much longer


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## Johnny B (Jun 4, 2019)

Well, you don't have to measure everything. But if you don't, I have to make assumptions. He was just like you, and many others coming here for help. You have replaced parts that were never never bad and over again, and then still have a broken car. Just being honest, its a daily event here.

Anyway....testing. I'm assume you lost the grounding to the battery from the alternator, like Ray.
1. Test the voltage for the alternator. Go from the alternator output stud to the alternator case, should be about 14.
2. Test the voltage from the output stud to the battery negative. If the reading is now about 12, you lost the grounding.

Probably the easiest thing to try first is one part of the Big3. Just add a ground, from the engine block to the frame.



















How-To: Installation of the Big 3 Cruze Kit


This installation guide applies to both the 1.4L turbo and 1.8L engines available in the Cruze. The 1.4T is covered first, followed by a slight variation that is found with 1.8L installation (thanks to Smurfenstein for the 1.8 info/pictures!) This simple how-to illustrates how to install...




www.cruzetalk.com


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## RavenMartinez (Jun 4, 2021)

What size bolt goes in on the block?


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## RavenMartinez (Jun 4, 2021)

Okay I ran a ground from block to frame, gave a quick drive and the interior electrical seemed to flicker less if at all, but the screen voltage display did show decrease as I accelerated all the way down to 12.0v. Will drive again later to check headlights at night


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## Johnny B (Jun 4, 2019)

RavenMartinez said:


> What size bolt goes in on the block?


8mm x 1.25 x 20mm


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## RavenMartinez (Jun 4, 2021)

Okay after adding the ground from body to block it did not improve any of the flickering of the lights, or the battery decrease when accelerating. I went ahead and hit it with the multimeter across all 15 points you listed in rays post.

Here are my readings


1. 12.67
2. 0.00
3. 12.69
4. OL
5. 0.02
6. 0.01
7. 0.01

8.15.1
9. 0.05
10. 14.5
11. 14.5
12. 0.10
13. 0.05

14. 0.0
15. 0.0 

I did measure and double check each time, hopefully I didn't mess up any of it but that's what I got. Although I'm still not sure what my next step may be, if I should go ahead and "big 3" the wiring or if maybe my ecm is screwing up or anything


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## Mastermech (Apr 10, 2021)

The situation sounds like an issue with the ecm not properly controlling the alternator correctly. I suggest you have someone with a scanner (not a code reader) check the alternator function via the ecm


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## Johnny B (Jun 4, 2019)

Mastermech said:


> The situation sounds like an issue with the ecm not properly controlling the alternator correctly. I suggest you have someone with a scanner (not a code reader) check the alternator function via the ecm


I disagree. The alternator is working, or seems to be by your readings. And to me that means the ECM is working fine (they usually do). That said, cleaning the pin / pin connector for the ECM is a good idea. And maybe check the connector on the alternator itself.

BTW, I fell asleep way early last night. I didn't have a chance to get back to you 

Anyway, reading the codes on your car is NEVER a bad idea.

Ok, now the bad news.  All of your readings look fine. I don't get it.

Do you have anything extra on your car? Lights, stereo amp, etc.


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## RavenMartinez (Jun 4, 2021)

Mastermech said:


> The situation sounds like an issue with the ecm not properly controlling the alternator correctly. I suggest you have someone with a scanner (not a code reader) check the alternator function via the ecm





Johnny B said:


> I disagree. The alternator is working, or seems to be by your readings. And to me that means the ECM is working fine (they usually do). That said, cleaning the pin / pin connector for the ECM is a good idea. And maybe check the connector on the alternator itself.
> 
> BTW, I fell asleep way early last night.  I didn't have a chance to get back to you
> 
> ...


No rush dude! And no i don't have anything extra like that, honestly just my rear defrost drops the voltage bad enough that I haven't even thought about amps or subs or anytging. Although seems to be fine at idle like 75 percent of the time, sometimes at a red light or stop sign it will start to drop by like .3v every two seconds or so. However every time I accelerate, usually a but above 2500rpm it starts dropping until I let off entirely. It seems to have gotten a little less intense with the new ground cable now that I've been watching it a day or so. The battery light hasn't come on at least but it did drop to 11.7 at one point, and then charged up to 15.6 another time. 

I've checked and cleaned all the fuses and I checked the ecm plugs and pins when I did and they seemed to look OK, but I'll go in and check and clean again to be sure. And I'll unplug and check the alt plug too. Hopefully I get somewhere with it lol


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## Johnny B (Jun 4, 2019)

RavenMartinez said:


> at a red light or stop sign it will start to drop by like .3v every two seconds or so. However every time I accelerate, usually a but above 2500rpm it starts dropping until I let off entirely. It seems to have gotten a little less intense with the new ground cable now that I've been watching it a day or so. The battery light hasn't come on at least but it did drop to 11.7 at one point, and then charged up to 15.6 another time.


I got thinking, maybe your problem is mechanical. How does your accessory belt look? Also, does the tensioner seem to be working?
At idle is IMO the worst condition for the alternator. The load on the system is still pretty high and the alternator output is low. So getting even a little slip on the belt might do what you're seeing.


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## RavenMartinez (Jun 4, 2021)

Well it's possible, there is an oil leak I've been chasing pretty much the whole time I've had the car that drips on the belt and pulleys, so it gets spin around the whole left side if the engine. Although it's been that way for a long time and never done this to the electrical before. The issue arose when I changed the valve cover a few months ago, not that the valve cover would do it either, just clarifying lol


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## Johnny B (Jun 4, 2019)

I had a couple more ideas. You said that the battery was tested. Well, what exactly were the results? What percentage did it show? Along with that, you don't have a racing battery or so a small battery?
If the battery is weak it might not be able to keep up with the load at idle. If the battery is older than about 4 years you might want to replace it, just to illuminate it as a source. 
Story time. My brother's car broke down once, after looking at the car I found the battery had a bulge in the side of it the size of a grapefruit. The moral of the story is just because the car starts doesn't mean the battery is good.


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## RavenMartinez (Jun 4, 2021)

Well I've had the battery tested a couple of times once at Walmart then once at O'Reilly both times they said it came out OK with full charge. I still feel like I should replace like you said to elleminate it in my mind. My car did just now die in a parking lot for the first time, stabilirak warning light, vatter saver notifications, then dash lights cut off and sudden loss of power along with power steering. Got it jumped off and it did the same thing immediately. Wtffff


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## RavenMartinez (Jun 4, 2021)

Alright, I replaced the battery today with a new one today, I even went up to H7 from H5 just because. Still got the headlights dimming and ****. I still don't think it's the alternator, as it starts and runs on its own at idle and driving. Maybe just wasted some money on it but at least I know it's not the battery now


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## Johnny B (Jun 4, 2019)

RavenMartinez said:


> I replaced the battery today with a new one today, I even went up to H7 from H5 just because. Still got the headlights dimming and ****. I still don't think it's the alternator, as it starts and runs on its own at idle and driving. Maybe just wasted some money on it but at least I know it's not the battery now


Nice, I went to an H6 myself. The H5 and H6 were the same price, so I figured why not.

****, this is starting really irritate me too!!! 

Did you check the belt too? And how about reading for any codes?

I'm really running out of ideas here. The alternator is working, therefore the ECM is giving it a signal, therefore the ECM is working. All the testing you did shows a system that is working fine. ARRRG!! About the only the only left is some kind of intermittent fault. *Before we go on I need to know if there is something you aren't telling me*. Like, did you submarine the car, pressure wash the engine bay, wrecked then repaired, etc. ?

Could you post some pictures? I'd like to see for myself wtf is going on.
1. Battery fuse box
2. battery pos and neg posts
3. battery chassis ground
4. alternator output post ( 4-7 will need to be taken from under the car)
5. alternator mount/ case
6. ground at starter
7. positive wire connection at starter
8. accessory belt
9. accessory belt while you are twisting it about 45 to 90 degrees


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## RavenMartinez (Jun 4, 2021)

I'm not quite sure what you mean on #9


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## RavenMartinez (Jun 4, 2021)

Further no I haven't had anything happen to the car like that. I replaced my valve cover when all this started actually months ago. I have no idea what happened as I was doing it alone, got it all put on and together, staryed the car and i noticed the headlights dimming. Replaced my alternator and nothing, replaced it again, nothing. 

Today with the new battery, it started with 13-14v, fluctuated at idle. Drove it and it dropped to 12.5 off the gas and 12.3 on it. I have not checked for any codes in a while, last time I did was while I was trying to figure this out the first time and O'Reilly told me I had a fan relay code or something. I'll try and remember to get it scanned again quick.


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## Johnny B (Jun 4, 2019)

RavenMartinez said:


> I'm not quite sure what you mean on #9


Twist the belt so I can see the ribs. The ribs will almost always show wear and/or crack before the rest of the belt.


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## RavenMartinez (Jun 4, 2021)

Oh I see the ribs on the belt are definitely worn, I Chang the belt fairly frequently due to the oil leak along the pulley side of the engine. I'll take a picture although the electrical issue never occurred with the last belt when it was worn.


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## Johnny B (Jun 4, 2019)

I'm just going to say this now. Ya, the guy is a bit odd. That doesn't make him wrong  
The good part of the video is between 2:00 and 6:00.






In my experience, if you clean the throttle body every 2 years you will not ever have an issue.
If you clean it in place it will only take about 30 minutes. Removing will help you clean it and only add about 15 minutes.

1. Remove negative battery cable.
2. Unplug throttle body
3. Remove throttle body
4. Clean with carb cleaner. Then place a small amount of oil (preferably a light machine oil, like gun oil) on both sides of the disc pivot.
5. Reverse steps.


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## CRUISE-CRUZE (Nov 8, 2010)

Well, one of my Cruze has the same issue since born! Dealers couldn't fix it ever so my solution:








Slow Alternator


After complaining about the battery a second time to a different dealer. And finally getting a replacement. I've been watching my volt gauge. The car starts with 12.2 volts regardless with headlights on or off. Start car up it drops to 12.0 volts. For a couple of seconds. Then jumps back to...




www.cruzetalk.com


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## RavenMartinez (Jun 4, 2021)

Okay it's been a couple of days, most recently I did go ahead and get some wire to run for the big 3 set up, alt to batt, block to frame, batt neg to frame. My battery seems to charge easier and hold it a little longer, but it still dips to around 12.2 when I'm on the gas for a bit. As soon as I let off it climbs. I didn't get any pictures because I'm retarded, but the connections across everything look good and clean. Checked the alt post, mount and the case. It looked oily but not covered, I sprayed it clean regardless. Positive and negative on starter are clean and tight. Battery posts and connections all clean and tight. I checked every single fuse in the fuse boxes, none scorched burned or blown. And I put a new serpentine belt on and cleaned all the pulleys as best I could. Headlights still dimming, fml. 

At this point I really don't understand what could be doing it other than the ECM, just a general guess tho.


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## Blasirl (Mar 31, 2015)

Have you checked for parasitic draws?


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## Theh2os (12 mo ago)

I had to pull out the On Star fuse to stop the power drain. I was jumping new battery every week until I pull the fuse out, now once a year to jump start the car.
Note: My car will not try to start if the battery was down in 11 voltage range.


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