2005 LR3 Alternator Going Bad?

[LandyBoy]

I am having voltage issues and they coincide with a whirring noise from the engine compartment. Have a new battery and wonder if some noise is common when an alternator is starting to fail. Either way the car has to go to the shop but I like to be somewhat informed once the "diagnosis" is delivered by the shop.

Thanks,

[bbyer]

I suspect the Electro Viscous fan behind the engine radiator is acting up. It is controlled by the Engine Control Unit, and not directly by air or water temperature. The fan may be OK but if the voltages are strange, then wrong signals seem to be sent to the fan.

In other words, if it is the fan making more noise than usual, it is a symptom, not the problem. It tends to fail locked up and making wind, (and noise), as opposed to silent and free wheeling - probably the better choice.

The fan is about seven hundred dollars plus labour so hope it is not gone.

[LandyBoy]

Spent the day cleaning the posts on the battery and replacing the brake light switch. After charging the battery she is running fine or so it seems. Starts right up and NO alarms of any kind. The noise in the engine compartment has totally disappeared and I have no idea why!

Had the alternator checked and it is pushing 13.87v with no load and 12.84v with high beams , heated seats and heater blower wide open. Tech was not convincing when he said he "thinks you need a new alternator". Got a second opinion and he said it's working fine - no alternator replacement needed. Thankfully I noted the fan functioning normally while working on the vehicle!!

What do you make of those readings? My plan is to drive her normally and see if the battery discharges again. If it does drain again a new alternator seems in order. Do you agree with my logic?

Thanks for listening!!!

Bob

[bbyer]

The voltage numbers sound good to me. One of the problems with the 3 is that its systems are different than most vehicles, hence norms are not what one would anticipate. I think that is why your mechanic thinks there is still a problem. Also voltages are temperature dependent - as the temperature drops below freezing, alternator output voltages tend to rise.

Under high load conditions, a normal alternator regulator setup would raise the voltage and the voltage would stay high until the load exceeded the alternator output and then you would see a drop in voltage.

The 3, not so. The regulator receives what is call a PWM signal from the ECM. Depending upon a number of conditions, emission controls being primary, the alternator amps and volts may cut back under increased load demand to reduce the hp required by the engine to operate the alternator. To compensate, the ECU cuts various loads off, say the heated seats, the heated windscreen, the radio amp etc. In other words, you may have turned a system on, but the computer has cycled it or dialled it back but there is rarely any physical indication of that.

There are a number of alternator and regulator related files, (among others), per the link below that attempts to explain the power generation system in greater detail. That is why the more stock you keep your 3, the better it will operate as what may seem like a minor change can have major consequences unless the affected systems are truly understood. I think the LR engineers are still learning; hence no one really knows all the quirks.

That is how a deteriorating brake light switch can affect the operation of the radiator fan - who would have thought? I expect your fan will be OK now except on very cold days when it may fuss a bit.

DISCO3.CO.UK Photo Gallery - LR3 miscellaneous

[LandyBoy]

OK - after driving after dark for several hours Red battery indicator came on and now stays on - also began getting the other warning lights flashing on and off. Charged the battery overnight and am now convinced I need a new alternator. Is there any reason I should be concerned about the voltage regulator as well??

Thanks,

Bob

[bbyer]

The part that most would call the regulator is located within the alternator. The regulator is the part that I call up as equivalent to the Transpo IN6349 part number. If you access the link in my above post, about a third way down within the album are five files related to the alternator and internal regulator. One of the files is a pdf of the alternator circuit wiring diagram and another regarding the Transpo IN6349 regulator.

Bottom line is that when you install a replacement alternator, you get a replacement regulator as well.

What you may be referring to however is that which controls the regulator. It is the ECM, the Engine Control Module that sends the PWM, Pulse Width Modulated signals to the "regulator". The ECM is probably OK as for these days, one does not hear of ECM problems on any vehicles. It seems over the years, the manufacturers have figured out how to build a rarely fails engine computer - or I suppose, to protect an engine computer from their dealers.

It sounds like the alternator does put out some power but not enough so over time, the battery looses what charge it does have. You may wish to purchase one of these cigarette lighter volt meters and watch it, particularily after you have installed a new alternator just to get an idea of what "normal" is.

A couple of years back, I bought and installed a ScanGauge II which plugs into the OBD Port and displays voltage as well as engine water temperature and a number of other parameters. I regard it as useful.

DISCO3.CO.UK Photo Gallery - ScanGauge II on LR3

[SafariDave]

Seems like same issue I am noticing the whirring noise and fan, but no warning lights. I am going to have the voltage on my Battery and Alternator checked. I already ordered the break light switch from AB.
Dave

[bbyer]

There is also another factor that I am beginning to think will disturb the viscous fan logic. As unrelated as it may seem, I think humidity will set the fan to remaining on for longer than it should.

By humidity, I mean whatever moisture conditions it is that will cause you to put the heating system into defrost mode will sometimes cause the viscous fan to not kick off - well it seems that way. I think it has nothing to do with the defrost cycle but is moisture content in the air instead. I do not know if the engine computer that controls the electro viscous fan has a humidity sensor within but it probably has.

I mention it as it is something to watch for as well. If my theory is correct, I suspect there is no solution - just one of those anomalies. Also the fan noise usually quits with an engine restart.

Most often however, the fan acting up is either brake switch or voltage related.

[SafariDave]

I had my LR3 connected to the LR computer today and we turned every electrical thing on and tested the voltage on the battery and on the alternator. So next is replacing the break light switch and see how that goes,
Dave