Not sure so far ive tested the battery it reads 13when engine is off. It reads 14.34 on and slowly gos down is this a case of a bad dieode in alt. or is my battery bad ,dont have much money and winter is comin plese help ps.when goes down it stays for about 5sec.then drops lower exam.14.34===14.32===14.30

Well every car made does this if driven long and far enough.
they ALL DO, and is not dreaded, it is expected,
belts, hose,fluids ,brakes, battery,,tires , alt and starter. (short lives)
fail. most never ever last the life of whole car. ever.
if you change that trend lets get rich> no? *a 500k mile ALT"
no no no, 12vdc is noT charging ever, 13-15vdc is charging
and 99% of DIY never read the service manual step 1.
remove NEG battery lug first or BOOM ,
or blow up the HUGE ALTERNATOR FUSE.
also some cars the PCM is the regulator and can fail too
and some have 3 fuse for the ALT, 1huge 2 small. we test them all first skipping not one.

ive no clue what is a
Transit? a FORD VAN? a MK5 VAN? WITH 15 ENGINE OPTION NEW, EUROPE.
EVEN BI-FUEL ENGINES, GAS AND DIESEL .
is it so hard to type FORD as they have other funny cars in EUROPE with that funny model name. SINCE 1965
no country told
no engine told , 100 TO 250 AMP ALT , FOR SOME ENGINES.
some have dual batteries and Dual ALTERNATOR OPTIONS NEW.

OUR PARTS HOUSE HERE HAS TO PARTS FOR IT.
SO WHERE ARE YOU, AFTER ALL PARTS AND MANUALS ARE FIRST BY COUNTRY . FOR SURE EASY TO SOURCE.

THE PROBLEM IS:
BLOWN FUSES, WHY NOT CHECK THEM ALL
AND THE 100 AMP ONE TO ALT NOT BLOWN.!!!!!!
AND IF THE SELLER OF NEW ALT SHOWS REGULATOR IS IN PCM THAT TOO CAN BE BAD.
AS CAN WIRES TO IT. .
WE CAN NO SEE YOUR VIN
NOR SEE UNDER THAT HOOD (BONNET?)
WHAT IS THERE IS ANYONE'S GUESS. SO FAR.

I GUESS ENGINE THERE
Alternator for FORD Transit Mk5 Van (V184, V185) 2.4 TDCi 03.2004 - 05.2006 (137 hp Diesel) H9FA HAS ON BOARD V.REGULATOR
SORRY NOT DOING ALL 15 ENGINES ME EVER.
IF YES FUES IS BLOWN
OR BUYING WRONG ALTERNATORS, FOR 14 OTHER WRONG ENGINES. OUCH.

Here is my Alternator 101 class for today, what can fail. (all) Jeff nails it. (2.4 or 4.3L engine I can not guess) both are internal REG.

1. battery is bad, if shorted cell in battery , altenator shuts down to prevent battery explode and acid every where. so test the battery first, for sure over 5 years old.
2. alternator swaps and blew the 100amp fuse there , next time pull battery NEG lug to replace any ALT. or blow it again you will
3. wires bad, or unplugged or connected backwards
4. the rear ALT plug has 4 pins all 4 must be wired end to end correctly,no hack jobs seen here. and ALt lamp pin next.
5. the cluster lamp ALT must not be burned out or self excitation fails and alt is born dead. replace the ALT lamp NOw. if blowned.out. in IP cluster.
6. bad alternator or wrong one there now.(hack jobs)
7. Engine idle RPM way way below 800 RPM and the ALT goes off line then,.
8. Fan belt slip to alt. pulley, (sorry typed this out of order)
9. a battery and anD alt both can be carried in hand to autostore and they test it, better stores do that, they load test the battery and spin test the alt.
10. tests: more, put battery from good car to here and test now.
11. jumper start the car, using 2nd running car, or ask a tow truck for a jump.
12. below I pust red donuts on all fail points 3 fase MUST BE GOOD , 0 OHMS MESSURED. best is with battery unplugged never use meter DMM ohms with voltage present.(tech 101)

\
the lamp must be good as vast regulators fail , reg is inside ALT.

In case battery is Bad. Stop Engine
Try a substitute Battery... Just use Jumpers Cables with main battery disconnected. Restart
If no change in Voltage (should go up to 13.8 to 14Volts) then your Alternator is Bad. (Belt Not Slipping?)
The Voltage regulator is usually built into the Alternator these days. So...Remove Alternator.
Either Repair it.
Place in Vice. Mark the case next to the screws with a scratch so it lines up on re assembly. Undo screws & Separate.
Faults Usually - Brushes, Diodes or Regulator
Check Brushes are not worn down too far to make contact.
If replacing brushes you will need to make a brush hook to hold brushes back on reassembly. Look for small hole to insert brush holder until both halves are back together.
or Get a Rebuilt one with warranty.

Not sure on your specific model, but they are usually either in wires near the battery + or near the starter big fat wire. You can identify them by close inspection of the wires to see a spot in the wire that looks as if something is spliced in. A small needle can be inserted into the wire on either side of the link to test for current passing through. When you find the bad one, making a good splice and soldering the new link in is best practice, using shrink wrap to insulate.

great questions...!!!
no it cant, mine can.
most dmm do 20 amps
most cars do 100 to 500 amps. cranked.
the alt can do 50, some more.
yes, its all DC, and the best tool is a DC amp clamp meter for $50
the alt is AC inside, and DC outside, thus the name.
why jnot say context what are you doing.
i need to know your plans.
dead battery ever 5 hours.
car wont start
battery explodes.
wires melt.
what?

testing the ALT on car , takes some skills
alts. can in fact shut down even when 100% OK (it's loansome)

most folks never read the spec on the VR.
its can be very complex this.

cases in point.
open ground or big wire.
battery going open inside. (cracks in battery or a cell dries up)
over volage (over 16v)
battery shorts. or cables shorts.
cable opens or ground opens/
some newer cars the ECU is the VR. ! !!!!
older cars the charge lamp out , nets you no, start up exciton field current (born dead ALT)

to do this we must know what alt we have.
the FSM covers that as does ALLDATA.com

so here are the 1st test.
12.6v at battery means charged (resetted and not freezing)
13.3- 15v running means the ALT is working
i stall engine
and leave head lights on for 2 mins. or so.. battery was discharged.
so i start up with my amp clamp (DC) clamped on to the
ALT big signal wire, it shows me 40amps.
good.
if not bad.
as i watch it ,it can drift to zero (or to 5amps ignition power)
note polarity , - is drain + is charging.
depends on clamp orientation, that is why i use discharge test first.
+40amps?

need more ask.

Batteries are difficult to test properly. They must be tested under load to determine the internal resistance... once the internal resistance is too high then you must replace the battery. Using a multimeter test the voltage. Write it down. Then turn on the headlights maybe even the radio and the blower, wipers etc (leaving the engine off) then take a voltage reading again. A charged battery should be near 14 volts readings below 12 volts shows a bad battery.

does the alt light glow, keyon (aka. chargelamp)? if not BAD !
fix that FIRST !
This is really simple in most cases.
it's a system, called a charge system.
it has 3 /4 parts.
1: Alternator must spin about 2 times crank speed.
if the engine RPM is 400 , the Alternator will give UP.
so first engine RPM 800 then i strobe the alt pulley, oops belt slips, mine runs at 1.8 ratio or 1400 rpm at alt pulley.
for a DIY is the belt tight?
2: is engine RPM at 800? no , fix that first.
3: RPM good.
The system now is ALT wires and battery. 3 things.
if the ALT is good and the battery is good (tested)
then it must be what. the wires.
The alt can put out 50+ amps..
there are at least 4 wires on most alts and any can fail.
1: big red. (huge charge wire,, or the inline fuse blown.
2: ground, old cars , and for sure in the SALT belt the gound fails
do to RUST, or better word, Corrosion and both.
alum and steel (iron) both corroded, add salt and its worses
in 2 ways corrosion and electrolysis. (google that)
so the ALT case must be grounded to the engine. 100% perfect
then engine ground stap to battery minus. if not the ALT will FAIL.
now we land on 2 more wires, most cars.
that rear connector.
1 is ignition sense wire, if open alt goes nuts.
2: is the idiot lamp. if lamp is bad, (dead) the alt can shut down.
this lamp creates boot up , initial excitation current, so the ALT can start up. most ALTS have no residual magetism to start up.
so it needs a bias circuit, to do that.
and guess what, each brand of ALT uses different parts here.
EVEN REBUILTS, so best practice, is to assume the lamp
must be good, and fix that first (early cars, ) new cars the ECU
runs the alt and is 10x smarter, not this car. at all.

no lie , testing the alt, in car is hard.
many times the ALt just shuts down. (faults)
and with zero current flow, you can not find the voltage drop
that precipitate that fall out/
there is a method but is risky , on car, called "full fielding"
it can blow up electronics,. so that is my warning.
does this help?

one other crazy failure
some cars have DRL , in uSA , some, in canada , many.
i fix them all. but the DRL in many cars, (this year)
connects the alternator, and DRL burns up and kills the ALT.
the reason DRL uses the charge lamp is easy
it shuts down DRL any time the Charge lamp is dead.
allowing more battery volteage (& current) to start, HEADLAMPS off.
same with cruise control some drop out , if change lamp is on.
to understand all this , its all in the manual. (parts effected)
at alldata dot com.

you will need to test this to be sure if its not charging then take it out and have it tested for free at autozone and get the replacement parts there also.
have the new one tested as well.
put a 12 volt test meter on the battery with the engine off.
take reading
then check reading with engine running .
take new reading.
if there the same the alt is bad.
volt should be be low 12 volts when off and should be above 12 volts when on.

keep me posted.
jm

turn off radio to keep from losing code.remove negative battery cable.disconnect wires from alternator .mark wires with tape to be sure they go back in the same place.loosen belt tension remove belt .if you have VR6-AAA-ENGINE remove the belt tensionsr from cylinder head .remove alternator adjustment bolt followed by pivot bolts .slowly lift alternator from bracket.smile take a deep breath dont need many tools.all you need is the basic tools. basic 3/8 socket set and open -close box end wrenches 13 up to 18 metrics.

well , the ECU runs the alternator. (DG wire "dark green")
the alternator field is controlled 100% by PCM reg , inside PCM.
so..... if the running engine has 13.3, to 15vdc the alt is working
if lower, its not. (rpm on engine 800 or more)

not scanning the PCM a the CEL glow, you missed the boat.
why not scan it. see why the PCM is upset (DTC errors stored)

see the 2 lower pins below , those go to PCM.
in theory if the field in the old BAD ALT, was shorted.
that could in fact, burn up the PCM regulator.
shorting outputs of PCM , does that in most cases.
im the poor sod that fixes PCM's.so....