I recently changed the alternator for a new DENSO DAN 672 alternator . It has a small 3 pin connector like the original but only two are used .....bad boys FORD .
Now there are 3 types of alternator.
Computer-controlled which we dont have . A high initial voltage cutting back to 13.7 to save petrol.
Machine sensed alternator . this measures the battery voltage at the machine (the alternator). Now this is fine if the battery is near the alternator and has a nice thick copper cable between battery and alternator.
Battery sensed alternator where a wire ( marked S for Sense) runs from the alternator to the battery positive having no other function but to tell the alternator what the battery voltage is. Now if this wire breaks the alternator reverts to machine sensed BUT AT A LOWER VOLTAGE. not good.
So you got it ford left the sense wire out and uses aluminium cables for economy and put the battery in the trunk.
Fortunatly this can easily be reversed.. the plug is available..chop off the old one and solder on the new one running a thin lead to the battery positive with a fuse at the battery end.
The three are S I L for sense ignition and lamp. Easiest way to fit is the match the position of the original wire to the new plug ..the one left over is the sense. fuse at the battery end .
Needless to say mine is on order. I can monitor the battery voltage on my Scangauge though this mod will not I suspect affect the fake voltmete.

 

Interesting. Do you have a link to the seller?

 

Jaguar did eventually get around to doing this on the 4.2L

 

if you go to ebay in the US and put in Denso 3 pin alternator plug you will get lots on offer ..some from china some US for about $12. Or you can Google the same and get suppliers.
the one identical to my photo comes from California_alternator_starter ..liiks like its a common item particularly when upgrading the alternator on US Toyota Trucks

 

Michealh...as always you are a genious ...that in part proves its worth checking on the 4l cars and putting in the extra wire .
At present I have the wire in but am waiting for the plug ...Mine is a 97

 

Got the live cable through from the trunk to the passenger compartment. Got under and the connector is accessible if you remove the air duct with room to solder . But how to get wire thro to the engine compartment? Looking for an elegant solution rather than drilling a hole ! Dont like running the wire under the vehicle .
Any one know of a grommet etc between the passenger area and engine. ( Too hot today to pull it all apart ..knee pad /glove box etc )

 

I did this mod on a car when I swapped a Supercharged engine ( Fiero!). The sense wire works good from the battery, but it works even better if it is located at a device that is pulling power. I used the wire to the fuel pump, but any wire that is constantly pulling power while running would work. Might be easier to find in the engine compartment than running a wire to the battery.

 

That is rubbish and defeats the object of battery sensed system

 

I was surprised too. On my El Camino engine swap, it was wired to the battery, but I always had charging issues. It would charge, but just not much. I was constantly having to put the battery charger on a dead battery if it sat more than a week. I then swapped an engine from a Riviera into the Fiero, and that is where I found that GM had wired it that way (found via thewiring diagrams). I switched the El Camino wiring, and immediately got much better charging. It's been 5 years now without a need for a charge. Worked on the Fiero as well.

Either will work. But battery sensed does not pick up on draw, and if you have a lot of electrical devices pulling power, I would rather see the alternator amp up and supply the voltage vs the battery.

From some of my research:
https://www.pirate4x4.com/threads/12...#post-44988321

Scroll down to Voltage Sensing.

Also, note that connecting the remote voltage sensing terminal to the battery will only result in the alternator being a good battery charger - it still won't compensate for voltage drop in the system caused by wiring to the main distribution point and increasing electrical demand as more components arepow.

 

I dont think you read my post on machine sensed V battery sensed. If a battery sensed alterator is being run in machine mode its output voltage will be lowered. Connecting the sense terminal to any battery live will raise the output voltage through connection to the battery terminal is preferable.
The alternator will always "amp up" ie supply vehicle loads. That's what its put there for and rated at 120 A . Battery charge current however will be limited to about 15A as only the difference between battery voltage (say 13.5v) and the alternator output (say 14.4v) drives the charge current and of course, this difference reduces.

 

Thanks Pistnbroke for posting this.
Interestingly this might be a critical fix for those who convert to AGM batteries which do better with a higher charge voltage.
Would happen that i had the seats, carpets and console out of the car at the time of your posting but did not see it.
Since your car is RT Drive, there should be a large bundle of wires passing through the firewall next to the power brake booster on the same side as the alternator.

 

Thanks for that . At present am working on Daughters wedding (nightmare ) and getting a roadworthy 2 days later .
There are two ways to do this .
Best ..run a wire from sense to the battery direct.
Next best ... join Sense to B+ at the alternator.
AGM is just a method of construction not a change in chemistry but as close to 14.4v as you can go . Over that the battery gasses and you have no means to fill it up ( unless you drill the top )

 

AGM is a sealed system that recovers its own water. if you over charge an AGM battery, it will vent and it's then destroyed. Drilling a vent hole in one could potentially allow hydrogen gas to fill the trunk of the car, possibly leading to an explosion.

 

I have done 40 year for years mate ...if you get a failed battery you can drill each of the cells to check the electrolyte level and if its low top it up and continue for another couple of years...plug the holes ..no problems

 

Thanks,
I read about shorting the sensor lead to the B+ as a method. Actually have a nice run of black automotive wire which matches my carpets, so might make something up as an interim fix .

The AGM technology at least in my market is vented as a standard flooded battery, in our size two ports, plug one and connect the other to the overboard discharge as they are contiguous.

I have what has turned out to be a rather accurate voltmeter/battery tester. With a fully charged and load tested battery, i get 14.2 at the terminals at 1500 RPM with or without all loads on. This shows that the alternator is doing what it should, however the loss over the distance and the OEM voltage sensing setup, means that charging is not really optimal. Now add in that for short trips with loads, idling, temp extremes, etc. batteries might be constantly a little on the low side. Long term, this could affect them. With the AGM it is more forgiving, yes, however still not optimal. As it stands in the automotive world, many charging systems are not designed to fully saturate a battery no matter how long one drives. The rule with LA batteries is to fully saturate them, and then not abuse or deplete them ever. Normal driving and state of vehicle repair are required.

Perhaps people who use tenders regularly are keeping their batteries at saturation, thus inadvertently making up for this minor shortcoming.

A while back in some other discussions folks were discussing the issue of attaching a tender where access was a problem, accessibility, perhaps an apartment situation. I have a setup which works for this. There are some round holes in the trunk floor which are closed with metal blanks. Remove one and install one of those waterproof RV, or better boat style, fixed AC male plugs. I mounted my CTEK over the CD changer and then wired its lead to the back of this exterior access plug. Now it is simply reach under and plug the female end of the extension cord. The car is closed, locked, weather tight and all equipment is locked inside. Best part is that this has a breakaway aspect. Nah, none of us have ever done this.