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Discussion Starter #1
Hi,

Which cable connecting going to the alternator is sending the signal from the ECU? How to test with a multimeter?

Some background:
Car died while driving. The reason was a drained battery. I've charged the battery and I've got it load tested, no fault with the battery.

The drivebelt feels fine and the generator looks running without slippage.

The voltage both at the battery and alternator is about 12V when engine is running bot with and without load. I've checked voltage drop are along both positive and negative side showing no issues.

So last thing I want to check before changing the alternator is that the alternator is getting the signal to charge the battery.

/ Anton
 

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Is your battery still dying after charging it and having it load tested? Why wasn't the alternator output checked at the same time?

When checking your alternator output you should be seeing well over 13 volts after a cold start in the morning.

You can find the service manuals here:
 

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Hi,

Which cable connecting going to the alternator is sending the signal from the ECU? How to test with a multimeter?

Some background:
Car died while driving. The reason was a drained battery. I've charged the battery and I've got it load tested, no fault with the battery.

The drivebelt feels fine and the generator looks running without slippage.

The voltage both at the battery and alternator is about 12V when engine is running bot with and without load. I've checked voltage drop are along both positive and negative side showing no issues.

So last thing I want to check before changing the alternator is that the alternator is getting the signal to charge the battery.

/ Anton
There is no signal coming from the ECM that controls alternator output in the 1st generation Murano (subsequent generations do have that setup). In the 1st generation, the voltage regulator controls output based on voltage it senses from the battery. If you're measuring 12 volts at the battery posts with engine running then just confirm that you're getting battery voltage on the S terminal circuit at the alternator connector and that the L terminal circuit is intact (...charge warning lamp should illuminate with key-on, engine off). If those check out (along with the voltage drop tests you've already done) then that suggests that the alternator is done.

You'll find a wiring diagram in the "Starting and Charging System" file of the service manual linked in the previous post.
 

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Discussion Starter #4
@MuranoSL2003 haven't driven the car since it drived (Beside getting it to my garage with another charged battery). Since the old battery was still under warranty I got it to the store where I bought it and got it load tested there. Thanks for the link, gold!

@I need coffee Ok thanks for the explanation.

I would say for sure now that it's the alternator that's dead:
1. Battery load test - OK
2. Cranking Voltage - About 10.5V (Don't know if the sampling rate of my multimeter is enough when cranking the engine.)
3. Voltage both by the battery and alternator is 12-12.5V on idle and a bit less with ac, fan, radio on (Engine on).
4. "L" terminal, when grounding F27 connector, terminal 3 with key "ON", engine off - The charge warning light illuminates.
5. "S" terminal, getting battery voltage from F27 connector, terminal 4 (Engine off).
4. "B" terminal on the alternator, getting battery voltage (Engine off).
5. Voltage betwen "B" terminal on alternator and positive terminal on battery (Engine ON, 2500rpm) - 0.05V
6. Voltage between Alternator case and negitive terminal on battery (Engine ON, 2500rpm) - 0.01V
7. Getting 24A output from the alternator on idle (Measuring with a DC clamp meter) - Should be over 35A on idle.

So what I've read there is two ways of removing the alternator?
The one described by Nissan witch includes empty the AC and removing it from underneath? The other one from above which I know @DreamCar5683 has made a video about.

Since I don't have any tools for either emptying of filling AC refrigerant I feel this is the only option to change the alternator?

BR Anton
 

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@MuranoSL2003 haven't driven the car since it drived (Beside getting it to my garage with another charged battery). Since the old battery was still under warranty I got it to the store where I bought it and got it load tested there. Thanks for the link, gold!

@I need coffee Ok thanks for the explanation.

I would say for sure now that it's the alternator that's dead:
1. Battery load test - OK
2. Cranking Voltage - About 10.5V (Don't know if the sampling rate of my multimeter is enough when cranking the engine.)
3. Voltage both by the battery and alternator is 12-12.5V on idle and a bit less with ac, fan, radio on (Engine on).
4. "L" terminal, when grounding F27 connector, terminal 3 with key "ON", engine off - The charge warning light illuminates.
5. "S" terminal, getting battery voltage from F27 connector, terminal 4 (Engine off).
4. "B" terminal on the alternator, getting battery voltage (Engine off).
5. Voltage betwen "B" terminal on alternator and positive terminal on battery (Engine ON, 2500rpm) - 0.05V
6. Voltage between Alternator case and negitive terminal on battery (Engine ON, 2500rpm) - 0.01V
7. Getting 24A output from the alternator on idle (Measuring with a DC clamp meter) - Should be over 35A on idle.

So what I've read there is two ways of removing the alternator?
The one described by Nissan witch includes empty the AC and removing it from underneath? The other one from above which I know @DreamCar5683 has made a video about.

Since I don't have any tools for either emptying of filling AC refrigerant I feel this is the only option to change the alternator?

BR Anton
Other videos online describe being able to move the AC compressor from underneath without disconnecting the pressurized lines, but my preference is to do the work from above. Even though removing the radiator and fans seems like more work...I personally like the extra room it offers to remove the alternator with more ease. Good luck to you either way.
 

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Discussion Starter #6
Other videos online describe being able to move the AC compressor from underneath without disconnecting the pressurized lines, but my preference is to do the work from above. Even though removing the radiator and fans seems like more work...I personally like the extra room it offers to remove the alternator with more ease. Good luck to you either way.
Yes, I've seen some of those videos.. But I find your video the most informative and since I watched your video replacing the clock spring and successfully do it on mine a couple a months ago, I won't change I winning concept :).

51782
 

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The brake fluid in that photo looks pretty dark, time for a brake fluid flush too.

Ideally it should be done every couple of years or so.
 
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