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2001 Subaru Outback
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Discussion Starter #1 (Edited)
Hello everyone! First time post. Asking for my 2001 Outback diagnostic help. Sorry for the noob post.
Here's the breakdown of the issue:

first thing I noticed was my ABS light started coming on during acceleration.
The next day after driving for 5-6 hours in the city (delivering food) suddenly the parking brake light came on. A few min. later the Battery light came on. The ABS, Batt, and Brake lights fluctuated on and off when gasing and braking. I drove it two blocks and parked it when this happened. The next morning I went to start it and the 3 month old battery was DEAD. Charged the battery. Now the Alt Fans wont turn on. Volt reg may be bad, reads over charging at 16 volts. I jumped the relay with a wire and they worked. Did ecm cause the alt/regulator to over charge or did the over charging damage the ECM?
Just in case this helps, my gas light is on too..but im also sorta low on gas, I seem to remember it coming on when the other did.
TY!
 

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2001 VDC/SC One of a Kind
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First thing is we need to know if it's an H4 or the H6. The alternators and their functions are different.

Did you measure the voltage at the alternator post or the battery?

If the alternator is putting out 16V, that's a regulator issue. It could also be a bad ground cable on the battery or a weak positive cable from the alternator to the fuse box. You'd have to test them with a multimeter.
 

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2001 Subaru Outback
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Discussion Starter #3
First thing is we need to know if it's an H4 or the H6. The alternators and their functions are different.

Did you measure the voltage at the alternator post or the battery?

If the alternator is putting out 16V, that's a regulator issue. It could also be a bad ground cable on the battery or a weak positive cable from the alternator to the fuse box. You'd have to test them with a multimeter.
Thanks for the reply! It’s the 2.5 4cyl. Is that an H4?

16 volts at battery at idle.

I’ll check those connections with multimeter and report back.

I’ve been scouring old threads trying to figure out what’s going on. I found a lot of good stuff on the multiple warning lights. Most of what I have read points to the alternator/voltage regulators, however, nothing I have read explains the radiator fans going out. I watched a YouTube video of a guy diagnosing his radiator fan problem, and his ended up being a bad ECM. I’m afraid I may have to replace the alternator and the ECM... but I’m sure it’s too early to tell.
 

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however, nothing I have read explains the radiator fans going out.
The fans (both, together) should run when the engine coolant temperature is high (certainly when above ~212 F), or, the AC is turned on AND the compressor is running. In both cases, the ECM controls the radiator fan relays (there's 3) to run the fans on low or high speed.

Jumping the relay verified that the fan motors themselves work, but it doesn't say whether or not the ECM is commanding them on when it should.

Do they run when the engine is warmed up (not overheating) and the AC is turned on?
 

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2001 Subaru Outback
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Discussion Starter #7
Update:
Tested the alternator post to ground...when i rev the voltage jumps to nearly 18 volts. regulator is trashed
just installed the new alternator and went to start and the battery is only at 7.5 volts. something is draining it obviously.
the radiator fans work only when AC on.

Im gonna jump it and check the new alt/reg.

any recommendations on trouble shooting the fan and the short. I'll check all the fuses and report back. Thanks for the help friends
 

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Discussion Starter #8
The fans (both, together) should run when the engine coolant temperature is high (certainly when above ~212 F), or, the AC is turned on AND the compressor is running. In both cases, the ECM controls the radiator fan relays (there's 3) to run the fans on low or high speed.

Jumping the relay verified that the fan motors themselves work, but it doesn't say whether or not the ECM is commanding them on when it should.

Do they run when the engine is warmed up (not overheating) and the AC is turned on?
once i get it started and warmed up i'll verify if the compressor is working with the fans
 

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just installed the new alternator and went to start and the battery is only at 7.5 volts. something is draining it obviously.
Recheck all the work done when replacing the alternator to be sure all the wiring is correct.

If the old alternator was pushing 18 V, the battery might have been damaged and perhaps can no longer hold a charge.

In your first post it's reported that earlier the battery had failed overnight, so this could be another instance.

And, of course, check the output of the new alternator once the engine is started.

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the radiator fans work only when AC on. . . .once i get it started and warmed up i'll verify if the compressor is working with the fans
If the fans (both) do run when the AC is turned on and is working (blowing cold air), then the ECM control of the fans is working as well. The fact that the fans might not run when the AC is off could be because the engine coolant temperature isn't getting quite high enough, i.e., overheating, which is fine.
 

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Discussion Starter #11
Recheck all the work done when replacing the alternator to be sure all the wiring is correct.
So, im trying to figure out why the fans wont turn on when hot, and a parasitic battery drain. Had battery tested and it tested good. just in case, i left the batt out all night to make sure it was holding charge on its own. it did.
Output of alternator is good at 14.3v or so. When i plugged the green 2 prong test connectors together under the steering wheel both fans clicked on and off so the ECM muct be good, right? All fuses are good too. both relays are working. battery in car last night and no drain. im so confused


If the old alternator was pushing 18 V, the battery might have been damaged and perhaps can no longer hold a charge.

In your first post it's reported that earlier the battery had failed overnight, so this could be another instance.

And, of course, check the output of the new alternator once the engine is started.

If the fans (both) do run when the AC is turned on and is working (blowing cold air), then the ECM control of the fans is working as well. The fact that the fans might not run when the AC is off could be because the engine coolant temperature isn't getting quite high enough, i.e., overheating, which is fine.
[/QUOTE]
 

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Discussion Starter #12
So, im trying to figure out why the fans wont turn on when hot, and a parasitic battery drain. Had battery tested and it tested good. just in case, i left the batt out all night to make sure it was holding charge on its own. it did.
Output of alternator is good at 14.3v or so. When i plugged the green 2 prong test connectors together under the steering wheel both fans clicked on and off so the ECM muct be good, right? All fuses are good too. both relays are working. battery in car last night and no drain. im so confused. how do i test to see if the temp sensor is sending a signal to the ecm when hot?
 

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When i plugged the green 2 prong test connectors together under the steering wheel both fans clicked on and off so the ECM muct be good, right?
From that, the ECM appears to be switching the fans as it should. But, did the fans only come on and off, or did they come on at one speed, then another, and then go off repeatedly?

how do i test to see if the temp sensor is sending a signal to the ecm when hot?
When you think the engine temperature is "hot" enough that the fans should be on, where is the temperature gauge pointer? Is it at the 9:00 o'clock position (i.e., close to horizontal) or is it higher, and if higher, how high?

The fans do not necessarily come on when the engine is in a range of normal operating temperatures; they will be turned on by the ECM only when the coolant temperature goes higher than a preset temperature, such as above 212 F. At 200 F, which is "hot", the fans would not be on.

There's a good range of tools that can be used to see what temperature the ECM has from the sensor. An "ELM" OBD bluetooth adapter with an Android cell phone or tablet operating an app such as Torque, or Torque Pro, can do it. Or, if you have a laptop computer, it can be connected to the car's OBD port using a relatively inexpensive adapter cable, and with free programs such as Romraider or FreeSSM running on the laptop, the coolant temperature signal can be viewed.

In regard to post #11 above, the following quote is attributed to me, but it includes your text. If you go back to post #11, there's a "edit" button at the top left of the post. Using that the post can be corrected for clarity (for up to 24 hours after it was originally posted).

475453
 
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