[75aces]

Parasitic draw in the fuse box. Start there.

 

[corollacoaster]

Check all the fuses, especially the alternator fuse.

 

[TeamYoder]

Assuming the new battery hasn't died since replacing the alternator, it sounds like the core charging system is working. I think your issue may be with the signal wire that runs between the battery light and the voltage regulator. If there is corrosion or other unwanted resistance along the signal wire route it could "trick" the battery light into thinking the charging voltage is low and turn the light on. You said there was corrosion on the regulator connector and maybe it has travelled up the wire.
Try checking the resistance on the yellow wire at the regulator. It runs to an 18-pin connector behind the glove box and should be pin 2. If the resistance is high, that is your problem.

 

[MatrixXRT]

Parasitic draw in the fuse box. Start there.

I have the same problem as the OP, dim battery light on an 05 Matrix, battery and alternator are both brand new now and have been tested at Autozone. Once I noticed my charge light on I checked my battery and found out it was leaking onto the top, the plastic top was in contact with the chassis so I found roughly 3V feeding backward from the battery into my chassis (ground), that battery was then replaced with my current one.

I have now discovered 0.285A parasitic draw but have removed every single fuse (engine bay including the alt fuse and inside the car) with it not going away. Additionally I have unplugged various components to no effect (radio, ecm, combination meter, and the daytime running light relay).

Assuming the new battery hasn't died since replacing the alternator, it sounds like the core charging system is working. I think your issue may be with the signal wire that runs between the battery light and the voltage regulator. If there is corrosion or other unwanted resistance along the signal wire route it could "trick" the battery light into thinking the charging voltage is low and turn the light on. You said there was corrosion on the regulator connector and maybe it has travelled up the wire.
Try checking the resistance on the yellow wire at the regulator. It runs to an 18-pin connector behind the glove box and should be pin 2. If the resistance is high, that is your problem.

I have checked my signal wire and the resistance was fine.

Other things I have done since this problem arose for me include: inspecting, cleaning, and testing all ground locations on the car and the belt and belt tensioner were both replaced.

Anyone have any other ideas?

 

[TeamYoder]

I have now discovered 0.285A parasitic draw but have removed every single fuse (engine bay including the alt fuse and inside the car) with it not going away. Additionally I have unplugged various components to no effect (radio, ecm, combination meter, and the daytime running light relay).

I have checked my signal wire and the resistance was fine.

Anyone have any other ideas?

A 0.285A parasitic draw would drain the battery fairly quickly (several days) if the vehicle isn't running but I doubt is sufficient to cause the battery light to come on.

Which signal wire did you check? There is one from the battery to the regulator that tells the alternator how hard to work and there is a second between the regulator and the battery light.

Other ideas - First, check your battery voltage before starting the car and with all loads off. Then, check the battery voltage with the vehicle idling and all loads off. The voltage at idle should be 13.5V or higher and should be higher than when the car was off. If so, this indicates that the alternator is recharging the battery faster than it is discharging. If the battery light was not on during the second voltage test, turn on enough loads to trigger the light and test the battery voltage again. If it over 13.5V the charging seems to be fine and the issue appears to be related to the battery light signal circuit.

 

[MatrixXRT]

A 0.285A parasitic draw would drain the battery fairly quickly (several days) if the vehicle isn't running but I doubt is sufficient to cause the battery light to come on.

Which signal wire did you check? There is one from the battery to the regulator that tells the alternator how hard to work and there is a second between the regulator and the battery light.

Other ideas - First, check your battery voltage before starting the car and with all loads off. Then, check the battery voltage with the vehicle idling and all loads off. The voltage at idle should be 13.5V or higher and should be higher than when the car was off. If so, this indicates that the alternator is recharging the battery faster than it is discharging. If the battery light was not on during the second voltage test, turn on enough loads to trigger the light and test the battery voltage again. If it over 13.5V the charging seems to be fine and the issue appears to be related to the battery light signal circuit.

Yes, it has been draining it fairly quickly.

I checked the one going to the combination meter (yellow, reg and battery light), I'll check the other as well.

When I shut my car off after driving it the battery voltage comes to rest at around 12.5-12.6V, then it slowly drains due to the parasitic draw. With my car running both with accessories turned on (AC, headlights, defroster, radio) and off the voltage is roughly 14.6V and the battery light is on, the only time I can get it to go off briefly is if I turn on the headlights then shut them off, the light goes away for an instant but then comes back.

EDIT: Checked the white wire from the alt to the fuse box and the black and green wire, both were fine.

 

[75aces]

Is there an accessories installed like a newer aftermarket head unit, dash cam, etc?

 

[MatrixXRT]

Is there an accessories installed like a newer aftermarket head unit, dash cam, etc?

I have three aftermarket gauges, some leds, an amp plus capacitor, and also an AEM FIC, all of those I have disconnected with the parasitic draw still remaining, additionally all are directly fused except the FIC which is connected to the ecm.

It is also important to note that I have additional symptoms with the battery light which I am 99% sure are correlated. My vehicle stalls when coming to a stop randomly (not all the time) and in addition to this I have stumbling issues at higher rpms or when trying to accelerate and subtler stumbling at a constant speed. I am able to monitor these conditions with my afr gauge and when this happens my car is going lean, I believe my injectors are losing power and it's electrical. I also have no CEL to speak of and no pending codes. My symptoms gradually got worse until I found and switched out the battery that was leaking, they have not progressed any further but have remained the same maybe slightly better.

 

[TeamYoder]

Try disconnecting the main alternator wire and seeing if the parasitic draw decreases. It is possible one or more of the alternator diodes has failed.

 

[MatrixXRT]

Try disconnecting the main alternator wire and seeing if the parasitic draw decreases. It is possible one or more of the alternator diodes has failed.

That was my original suspicion, I installed the new alternator before I realized the battery was leaking so the battery could have potentially damaged it. I took it to Autozone and the Alternator tested fine, additionally I did what you said and it had no effect on the parasitic draw. I also performed a diode test with my multimeter and it tested fine (assuming I performed the test correctly).

 

[98_Corolla_LE]

I have found that just cleaning a ground does not always make it good. There could be corrosion where the wires make contact with the eyelet.

Check out this video...Bad Ground

It may be worth a try to redo the grounds. A good place to start.

 

[75aces]

I don’t know if it’s possible for corrosion to get under the insulator of the positive cable. It sounds to me that either the alternator is a bad unit internally, or you have a electrical gremlin.

Try swapping the alternator under warranty. The equipment used to test components can be misleading. Do a voltage drop on the alternator. I have a feeling that the alternator you bought is faulty and needs to be replaced under warranty.

 

[MatrixXRT]

I have found that just cleaning a ground does not always make it good. There could be corrosion where the wires make contact with the eyelet.

Check out this video...Bad Ground

It may be worth a try to redo the grounds. A good place to start.

Great video! I will definitely do that.

I don’t know if it’s possible for corrosion to get under the insulator of the positive cable. It sounds to me that either the alternator is a bad unit internally, or you have a electrical gremlin.

Try swapping the alternator under warranty. The equipment used to test components can be misleading. Do a voltage drop on the alternator. I have a feeling that the alternator you bought is faulty and needs to be replaced under warranty.

That's a good idea, it's still under warranty. I do still have my 17 year old original alternator (tested fine at Autozone before I replaced it) so I may try swapping that back in to see what happens, my problems were still occurring when I had that one installed though, I'm not sure if the battery light was on at that time since it is very dim and was hard to see originally anyway.

Forgot to mention, another thing I have done since this issue manifested is put in new terminal post connectors for the battery as the old ones were corroded.

 

[75aces]

Great video! I will definitely do that.



That's a good idea, it's still under warranty. I do still have my 17 year old original alternator (tested fine at Autozone before I replaced it) so I may try swapping that back in to see what happens, my problems were still occurring when I had that one installed though, I'm not sure if the battery light was on at that time since it is very dim and was hard to see originally anyway.

Forgot to mention, another thing I have done since this issue manifested is put in new terminal post connectors for the battery as the old ones were corroded.

I went though a similar situation. My terminals were corroded and the copper was fatigued and stressed. I used wallyworld universal terminals. The copper strands kept falling out of the terminal and caused no start condition.

What style terminals are you using?

I found a good used oem terminal in the junkyard. Had to splice the wiring to connect it from the starter, starter solenoid, and the oil pressure switch. It looked oem under the sheath.

 

[MatrixXRT]

I went though a similar situation. My terminals were corroded and the copper was fatigued and stressed. I used wallyworld universal terminals. The copper strands kept falling out of the terminal and caused no start condition.

What style terminals are you using?

I found a good used oem terminal in the junkyard. Had to splice the wiring to connect it from the starter, starter solenoid, and the oil pressure switch. It looked oem under the sheath.

I got some generic ones off of Amazon, they have screw on connections for the eyelet terminals of the cables. I don't think my original ones had failed yet but they were nasty looking, I replaced them in hopes that may fix my problems but it did not.

 

[75aces]

The positive terminal is in 2 pieces. There’s a nut that connects the base which has the eyelet for the positive terminal.

Napa sells the terminals that can be soldered and crimped. I have a set, just don’t have a crimper for 0 gauge.

 

[MatrixXRT]

Just wanted to update on here as I finally got around to continuing to work on my car. First I redid all the ground locations in the engine bay that I am aware of. One on the passenger side, two on the driver side of the block, and then one on the driver side and there was no change with the battery light. I did not touch the other ground locations in the car as they looked like they were still brand new (no corrosion or anything). The next thing I did was swap out my new alternator for my old original one and magically the battery light disappeared.... OP, you may try swapping your alternator again.

I have yet to drive it and see if my other symptoms are still present but I am fairly sure they will be as I had them before I swapped alternators. I do still have a 285mA parasitic drain that I cannot find the source of. I'll be swapping my new alternator as it is still under warranty and update again if there are any changes.

 

[98_Corolla_LE]

@MatrixXRT You have added a lot stuff to your car. I would disconnect them one by one to see if one is the cause of your parasitic draw.