Hi there,
I am in need of some technical advice on the Denso Dan 672 12v 120 Amp alternator for my Car.

I purchased one from Amazon on 21st April to replace my 16 year old original OEM Denso LNC1800AA and that was intermittently charging especially when the car got hot.

However having wire brushed the fitting area around where the alternator sits (to ensure good ground earthing) I find the new alternator is performing less reliably then the 16 year old version. The car's computer dash board shows the battery warning light and Measuring the voltage at the battery when the engine is running I am only getting 12.4v (12.6V whilst engine off)

I was told on a car forum it maybe earth wire securing the gearbox/engine to the body and have replaced that as well as cleaning the area of contact and replacing the bolts. Also have checked the resistance of main Battery + wire from battery in boot to engine bay and seems 0.0 Ohm

Have double checked (removed and cleaned up) )wire going from alternator + stud to the starter motor and seems tight and clean.

QUESTION:

I am wondering if having a fault on the thin wires that go to the voltage regulator on the dan672 would stop the alternator producing any voltage?

I have also clean the false bulkhead stud by taking it apart and sanding its bits then applying vaseline to coat against further corrosion and ensure good electrical contact. Same on battery contacts and around mega fuse distribution box connectors/ contacts.

Please can someone help me.

 

Hi Jim, First have you checked fuse 2 (5amp) in the engine fuse box this powers the regulator.
Earth to the alternator is via a suppressor and not the alternator body.
Also the check the small Yellow wire from the alternator when the engine is running. It should be 13.9v to 14.2v.
You can download the schematics from here http://www.jagrepair.com/images/Auto.../jagxj2000.pdf
Hope this helps.

Roger

 

Hi Roger, thanks for replying.
I have just been in and under the car investigating.

Checked fuse 2 (5 amp) good working order 0.00 Ohm resistance.
Used my voltmeter in ammeter mode and a fuse holder attachment I was able to determine fuse 2 (5 Amp) has no current either before engine start or after.

I have got to the underside of the alternator and after a while I removed the voltage regulator plug. It has 1 grey coloured wire maybe you referred to it as slate? and the other wire is White with red dots on it.

Followed this wiring loom around it seems to goto the oil sump and up to the MAF sensor and then around to the main injector/throttle control body etc so I hope it is not the wiring loom at fault.

My main suspicion is the fusebox which was corroded and I cleaned up 6 months ago and had to resolder bits in due to dry joints.

Edited.

Still with the alternator regulator plug disconnected
Tested the voltage (WITH ENGINE OFF) at the grey (slate) wire 0.001v
...white wire red dots 0.02v

Tested the resistance to know good earth
Grey slate wire 1130Ohm
White wire red dots == infinity

Did not want to strip the back of the wires to test whilst connected in case this caused further issues.

 

Which fuse box have you worked on? From the front of the car, the 2 on top of the RH inner wing are engine control and can certainly throw up faults. Is it possible to exchange for a good condition s/h unit, hopefully the wiring going in underneath is in good shape?

 

Check the voltage from the alternator output terminal (the big wire) to the case. Then drom the big wire to car chassis. If they are the same, the ground strap is not the problem.

 

Was it rebuilt by Denso? In the USA most of the units sold as "Denso" are actually OE Denso units rebuilt by others ... normally in china.

Some are fake --

It's not unusual for them to fail.

 

The fuse box is the main 22 way fuse box in the engine bay, with fuse 2 being the 5 amp to the alternator.

I have ordered a 2nd hand used unit from online and hope to receive a working box later this week.
LNC 2822 BD

 

Occassionally it is best to haul the car to a specialist: when my battery wouldn't charge, I was unable to remove the alternator, so I took it to a local guy who rebuilds these: $200 and forty minutes later, problem solved.

Did the same thing on a Cadillac a few years ago; this time, I was able to get the thing off. Watched a guy who rebuilds a couple hundred a week redo everything for $60.

 

OK Replacement LNC 2822 BD fuse box arrived today from a well known auction site.

Cleaned up the main bolt terminal as was corroded as well as the blade connectors on bottom.

Fitted fusebox, checked my connections to alternator, then put fully charged battery back in car and started it....



*Does a little dance* The Dashboard battery light went out and no errors on dashboard computer.

Got my voltmeter 14.29V at battery with engine running.

Left it running 5 mins, voltage remained within 0.02v of that the whole time.

Will have to do a longer test actually driving the car. But thunderstorm outside says not a good idea at the moment.

 

The US is always free to embargo the import and distribution
of these units in favour of domestically rebuilt units.

Ever tried to find them in volume outside of a local rebuilder?

And if you did, the quality would be the same or worse once
the cost cutting managers have their way.

Offshore sources would be more than happy to provide the
highest quality available .... provided the US based importer is
willing to pay the price.

The problem is the US based importer not the supplier.

Pay a fair price, get a good product. Go cheap, get an
inferior product.

 

Well done Jim. First impression sounds great.

Roger

 

OK Driven it twice today in reasonable traffic so it heated car up a lot (25'c) air temp in London, UK, alternator still charging.

However the replacement fuse box seems to have stopped my air con producing cold air, which was certainly working 1 week ago with the old fusebox. :S
Still a hot driving car is better than a cold go nowhere car.