Dear "5 zeros";
I have read and reread what you posted. My Expy is a 2004, a 2nd gen. I think your 2008 is a 3rd gen isn't it? I don't think my Expy has the "Smart Charge" system. I'm not certain of that though.
However, in general a lot of what you posted applies to my gen2 Expy I believe. I don't think my Expy has a "limp home" mode although on two occasions I have manually limped home!
I have read about battery voltage and battery temperature although I am not completely clear about the relationship between a battery just sitting in a vehicle and the ambient temperature outside of the vehicle. I also had not heard about PCM voltage varying with air and coolant temperatures. Is that a "Smart Charge" system characteristic? I have not read that in my Ford Service Manuals. Perhaps I have not been looking in the right places.
RE a possible dead cell in the battery: I had it tested at the local Ford dealer and it came up as being good. Is it possible that the test instrument the dealer used can't detect a dead cell?
I am suspicious that my alternator is bad because even when the "check charging system" light is not on it fails a test from the Service Manual. That test is a check of voltage drop between the output terminal of the alternator and the positive pole of the battery. The book says that a drop of less than .5 Volts, or 500 mV (millivolts) points to a bad alternator. I got around 110 mV or so, at 2000 RPM under load (high bean headlights, climate control fan top speed, rear window defroster on). When the "check Charging system" light came on I got only 2.4 mV. Both figures are well below .5 V (500 mV). Am I missing something here?
From a 1975 Ford Instructional film I got the following advice: 1. check base batt voltage 2. check no load voltage engine running, look for 2V or less increase 3. Full load 2000 RPM look for increase over base up to .5V. From 2004 Ford Workshop Manual test for The Charging System Warning Indicator is on with the engine running (the charging system voltage does not increase) There are 5 "B" tests, the last one is the voltage drop test outlined above.
In all fairness I must admit that there are three tests involving the other alternator connections. I don't know how to get that connector off the alternator - the book says that it is a new style connector but does not show how to make it release.
DJ04
Ugh = been lurking here for a while ~ I'm in Central Virginia [Forest] ~ a proud owner of a
"mechanic's special" 2008 XLT 4x4 ~ Thought now would be good time to welcome myself
to the "Forum" seemingly a civilized bunch & guess this is ok => So - I'm the eldest son of
an electronics engineer (I'm also university educated) and have what we call 2 copies of the
"Ford" gene {my experience goes back to our beloved '55 Fairlane which had a generator}
ILC = Load Input Connector & ALF = ALternator Field Frequency => obviously, this is all
completely unnecessary and serves to support the maddeningly innovative "idiot light"
Seriously, Ford's not that much better idea calls for a "Smart Charging System" The SAE
{society of automotive engineers} are notorious for cryptic acronyms (automotive electrical
engineers even more so) Wonderfully, the "bit freaks" have even provided for a second
alternator (guess I'll save that for later) I'm busy and will just paste some info here = hope
this provides some enlightenment ! Skoal ! ~ J ~
Functional scope1. Charge voltage regulation and calculation of battery temperatureSince warm batteries are more efficiently charged with low voltage and coldbatteries with higher voltage, the charge voltage is adapted by the PCMdepending on the battery temperature. Reference parameters for calculation ofthe battery temperature are intake air and coolant temperature.The battery charging current is optimised through permanent calculation of thebattery temperature and adjustment of the alternator output voltage.2. Alternator switch-off when engine startedWhen the engine is started, the alternator is deactivated by the PCM to reduce the engine dragtorque. The alternator is only switched to the required valueelectronically by the PCM after the engine has been started up.3. Increasing idling speed at low voltage and high electrical load.When the battery charge is very low or the electrical load in idling is very high,the PCM can gradually increase the speed up to 150 rpm in order to increase thealternator performance.4. Advance notification function for alternator loadThe PCM receives information about imminent electrical load from thealternator via the signal cable, and can thus compensate the alternator torqueto be expected by increased idling speed.The PCM can guarantee greater idling stability on the basis of thisinformation. By monitoring the vehicle electric system voltage, the PCM canchange the charge current by changing the pulse-width modulated signal to thealternator.
5. Activating or deactivating electrical consumersBy linking the PCM with the central electronics module, the followingconsumers are activated or deactivated in the event of overvoltageor undervoltage depending on battery voltage:• Heated windscreen• Heated rear window• Air-conditioning system (if appropriate)• Auxiliary heater (if appropriate)The low-voltage limit is around 10.3 V, the overvoltagelimit around 16.0 V.Damage caused by excessive vehicle battery charge is reduced by activatingindividual consumers, and at the same time the charge voltage is kept withinthespecification. Switching the consumers on increases the engine load and thusserves to support the control unit at the same time in the warm-up phase. If thebattery voltage falls below the limit value, the consumers are deactivated againto prevent excessive discharging of the battery.6. Diagnosis and limp-home functionThe diagnosis possibility of the Smart Charge system is implemented throughtheengine control unit (PCM)System faults are stored in the engine control unit and can be read out using adiagnostic unit. After the ignition has been switched onthe system carries out a self-test. If a fault is detected in the “Smart Charge”system during the self-test, the charge control lamp is not switched off. Thealternator is operated at a fixed charge voltage of 13.5 V if voltage regulation isnot possible on account of the reason for the fault. This enables the alternatorto generate enough current to supply the vehicle systems.During driving, the charge control lamp is only switched on if the PCM detectsthe following faults:• Impermissible voltage• Internal alternator fault• Communication fault PCM/alternator
Hot here [My Noorse Boskat Scheherazade hates the AC => can't smell Los Coyotes about]
Suspect that 14.5 V. is a typo and should be the limp home (default) 13.5 ~ That 11.8 you
are getting almost certainly points to a dead cell [in summer most V8s w/ a heavy duty
battery will start with a dead or dying cell] nowadays doubtful that adding electrolyte will
cure a dead cell [yet not impossible] FYI decent multimeters are mighty accurate = a quick
test of a healthy battery while running @ idle = 12.9 V. @ the battery terminals . . .
