My scanner says that my battery and alternator are bad but my meter readings look good.

CES

Available voltage @ the battery with the engine off. Negative to negative positive to positive.



At the battery with the engine running and loads off.



Available voltage at the alternator - red lead to the alternator output post and black lead to battery negative with engine running and loads off.





Voltage drop test- with loads on. blower motor on max highbeams on AC on.

Low voltage at the OBD port or a junk scanner.

Voltage drop test of the alternator output cable. Red to alternator stud, black to battery +.
The voltage drop was .55v so cable was upgraded to a 4 gauge cable. From two 8 gauge cables that are wired in parallel from the factory.

Voltage drop of the ground side next. Measure negative circuit voltage drop by placing the black lead of the voltmeter on the housing of the alternator and the red lead of the voltmeter on the negative battery terminal. If the reading is less than 0.03 volts, verify the alternator is charging and retest.

negative
.04v voltage drop

Haven’t checked ac ripple but voltage at the battery is 12.53v and 12.08v @ DLC.

This is the scan tool

Just relax brother. People will chime in soon.

Much better this time, thanks.

I assume that voltage measurement at the OBD2 port wasn't with the engine running. If it was there's a huge drop between the alternator output and the OBD2 plug which could explain the Scanner complaining or you might be testing when the ECU thought it didn't need to be charging. Even so the roughly 12v would be too low and throw off the Scanner.

You might want to clean the rust off the negative cables and make sure the one to the firewall is also clean.

Thanks,the engine was off

I also noticed a red wire with tape going to the back of the dlc when I was under there

Is .45 too much voltage drop for pin 16 im thinking Thats were the problem maybe

Here's the deal. If your ECU is activating the CEL and reporting an problem with the voltage it would be worth chasing this but I'm not sure there is anything other than a voltage drop to the port and some unknown wire connected that is giving the scanner heartburn.

Perhaps a previous owner tapped into the power at the OBD II port to power a gauge.

I still don't care for the condition of the connections to the battery terminals. The wire in the two black cables to the positive post look corroded as does the connections to the negative. I'd try cleaning them up or perhaps get some battery wire ferrules for the wires into the positive terminal so you're not trying to clamp on loose wires.

Today the battery and brake like came on at the same time, flashed went away ?

And recently my turn signals stopped working but are currently working

Did you try cleaning and readjusting the battery cables that are corroded?

GhostTypeP0300 said:

Today the battery and brake like came on at the same time, flashed went away ?

Click to expand...

Those two come on when the alt isn't putting out (which can also be when the engine is barely running - too low rpm for alt to work).

I agree with Steve. Clean the rust off (use sandpaper) under that bolt head (remove bolt) holding the large black negative cable onto battery negative terminal. Also clean ALL mating surfaces (even the part of the bolt that touches) with the cable and terminal below it. All mating surfaces must be sandpapered clean and tight. Is the other negative black/yellow stripe wire frayed? If so, need to replace.

And the two black wires on battery positive terminal are corroded - need to fix by either (1) cleaning wire ends and soldering them to wire ferrules as Steve says, OR (2) replace the battery terminal with the type the negative one uses [which is a WAY more secure way with a bolt holding lugs soldered on the ends of the cables - instead of using the insecure, easily corrode and break the wire, easily wiggle loose, set screw type battery terminal].

Clean off the negative terminal ground wire bolt, remove the bolt and sand it down or replace that rusty bolt on the terminal

Go to your local auto parts store and ask for a battery and alternator test, voltage doesn’t tell us the amperage. The alternator needs to have a heavy draw test at hot idle, the alternator may put out good voltage at idle with the hood popped, but get extremely heat soaked and loose tight tolerances being cooked by the turbo while trying to power the fans at high output

Alternators for our cars are nearing new box failure age, the alternators on the shelf were rebuild many times more than ten years ago in third world countries and can fail new out of the box. It wasn’t until about 7 or 8 years ago that China and Mexico saw drastic improvements in manufacturing, hell in 2008 Korea could barely make a reliable Hyundai let alone have a rural factory in China rebuild an alternator for an American market car

When in doubt test the alternator at the parts store. I can’t recommend a specific brand but the parts store should stand behind their lifetime warranty. Bench testing an alternator in a sterile tester in the parts store can test good, but with 200 degree temps under the hood bearing tolerances can be stressed enough to not allow proper charging or contact with the brushes. So always test an alternator when hot while installed on the vehicle, take a long drive and then have the parts store check the alternator with the car running at hot idle

Everything tested fine at AutoZone, not sure why the flickering lights. I did upgrade the alternator output cable. I'm thinking maybe a loose connection were I bolted to the fuse. Not sure yet and also checked the alternator plug and it clicked when I pushed it, so maybe a loose connection there. I haven’t cleaned battery terminals yet. I'm thinking that running a new wire from the battery to pin 16 would fix the problem.