I am having a charging problem with my 5sfe 2001 Solara that started when the battery was low and the car wouldn't start one day. I checked the battery date and it was almost 10 years old, so I went to the store to get a replacement battery. Upon putting the new battery in, the idle was too low at around 450-500RPM and the engine was running terribly. I put a voltmeter on the battery terminals and the car wasn't charging. That explains the low battery, but I noticed that if I kept the RPMs up it would keep the system above battery voltage but anywhere near idle speed(<2000rpm) and the battery would begin discharging.
Thinking it had to be the alternator since this problem started suddenly, I ordered a new one. Well the new alternator is acting the same way the old alternator was. Part is correct, pulley size is correct and belt is not slipping. This is where the electrical diagnosis started. Here are the conditions:
Idle (~600RPM): No accessories or lights on, voltage never goes above battery voltage 12.5V, and system voltage quickly decreases to below battery voltage as alternator is not charging at this RPM at all
1000 RPM (Well above normal idle speed): No accessories/lights on, same as above just not quite as bad (aka still discharging just less quickly)
2000RPM: With no accessories or lights car makes 14.4V, with only lights on 12.7V (notice the huge drop from just headlights), with lights and fan on high 12.7V
Every single fuse has been visually checked and continuity checked, exterior and interior, yes every single one so please don't suggest this. I even cleaned the fuse blades. Yes the fusible link was checked as well.
Every single engine ground point was removed and wire brushed including the fasteners then cleaned and reinstalled. I checked that the control terminals on the alternator plug are getting correct voltage for both constant 12V pin and switched 12V pin. I also checked that from the alternator output terminal to the (+) battery terminal were getting very close to the same voltage aka voltage drop test and did the same between the alternator case and the battery (-) terminal.
Visual inspection of the entire charging circuit was done and everything looked good, various checks of continuity of grounds were good. I even added new grounds to the alternator case to rule out that the mount wasn't grounding correctly. The harness at and around the ignition switch all looked normal, car still starts right up just won't charge.
I read that throttle body issues can cause weird problems including charging issues with Toyotas, and since I was having an abnormally low idle I decided to pay some attention to this area. I removed the throttle body and then the IACV, both of which I have cleaned before in somewhat recent time. Nothing crazy here, except that the IACV resistance readings were way out of spec. So that is probably what's been causing the idle issues. Mine wasn't even dirty but I am pretty confident it has failed because the resistance readings were crazy far from spec. I am waiting on the new IACV to be delivered, however I am not convinced that this has anything to do with the charging issues I am having.
The voltage levels during different conditions I posted above show me that even if my idle speed picks up about 150RPMs to where its supposed to be, that it won't affect the charging system. The battery symbol on the dash lights up during key on (before start) like it is supposed to but while the car is running it doesn't turn on even when the running voltage is 12.5V. The IACV short circuiting is the only idea I have but that is such a longshot and I don't even know if that's possible or if it could even cause what is happening.
I did loaded voltage drop tests on both sides of the circuit and it passed with very good results.
I don't have an oscilloscope to test the wave form voltage to the alternator control plug which is the only test left that I can think of. I am also going to pull all non essential fuses to rule any short circuits out.
Are there any other tests I can perform before swallowing my pride and going to a shop? Is the new alternator bad (or specifically regulator)? The annoying thing is I purchased the new alternator from RockAuto and I assume I would need some form of shop proof that the new one has a bad regulator. To be honest I am not even convinced at this point that this is what's going on, because the old alternator was doing the exact same thing (not charging at idle or close to idle, and charging at 2000+ but not enough with lights or accessories on). Open to any ideas that are not things I have already done, as I did each test that I mentioned multiple times.
Thinking it had to be the alternator since this problem started suddenly, I ordered a new one. Well the new alternator is acting the same way the old alternator was. Part is correct, pulley size is correct and belt is not slipping. This is where the electrical diagnosis started. Here are the conditions:
Idle (~600RPM): No accessories or lights on, voltage never goes above battery voltage 12.5V, and system voltage quickly decreases to below battery voltage as alternator is not charging at this RPM at all
1000 RPM (Well above normal idle speed): No accessories/lights on, same as above just not quite as bad (aka still discharging just less quickly)
2000RPM: With no accessories or lights car makes 14.4V, with only lights on 12.7V (notice the huge drop from just headlights), with lights and fan on high 12.7V
Every single fuse has been visually checked and continuity checked, exterior and interior, yes every single one so please don't suggest this. I even cleaned the fuse blades. Yes the fusible link was checked as well.
Every single engine ground point was removed and wire brushed including the fasteners then cleaned and reinstalled. I checked that the control terminals on the alternator plug are getting correct voltage for both constant 12V pin and switched 12V pin. I also checked that from the alternator output terminal to the (+) battery terminal were getting very close to the same voltage aka voltage drop test and did the same between the alternator case and the battery (-) terminal.
Visual inspection of the entire charging circuit was done and everything looked good, various checks of continuity of grounds were good. I even added new grounds to the alternator case to rule out that the mount wasn't grounding correctly. The harness at and around the ignition switch all looked normal, car still starts right up just won't charge.
I read that throttle body issues can cause weird problems including charging issues with Toyotas, and since I was having an abnormally low idle I decided to pay some attention to this area. I removed the throttle body and then the IACV, both of which I have cleaned before in somewhat recent time. Nothing crazy here, except that the IACV resistance readings were way out of spec. So that is probably what's been causing the idle issues. Mine wasn't even dirty but I am pretty confident it has failed because the resistance readings were crazy far from spec. I am waiting on the new IACV to be delivered, however I am not convinced that this has anything to do with the charging issues I am having.
The voltage levels during different conditions I posted above show me that even if my idle speed picks up about 150RPMs to where its supposed to be, that it won't affect the charging system. The battery symbol on the dash lights up during key on (before start) like it is supposed to but while the car is running it doesn't turn on even when the running voltage is 12.5V. The IACV short circuiting is the only idea I have but that is such a longshot and I don't even know if that's possible or if it could even cause what is happening.
I did loaded voltage drop tests on both sides of the circuit and it passed with very good results.
I don't have an oscilloscope to test the wave form voltage to the alternator control plug which is the only test left that I can think of. I am also going to pull all non essential fuses to rule any short circuits out.
Are there any other tests I can perform before swallowing my pride and going to a shop? Is the new alternator bad (or specifically regulator)? The annoying thing is I purchased the new alternator from RockAuto and I assume I would need some form of shop proof that the new one has a bad regulator. To be honest I am not even convinced at this point that this is what's going on, because the old alternator was doing the exact same thing (not charging at idle or close to idle, and charging at 2000+ but not enough with lights or accessories on). Open to any ideas that are not things I have already done, as I did each test that I mentioned multiple times.
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