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P0621 atlernator codes

Alt replaced low battery lites stays on wiring ok

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2 Answers

P0621 comes on couple seconds after start.


have your alternator rechecked it could be bad even tho its is new this is very common .

Jan 12, 2014 | 2000 Cadillac DeVille

1 Answer

Battery light alternator


The Charge lamp comes on with the Alternator fails to keep battery charge going. (lots of way to fail, and ALT Is 100% good) it's a system. each part of it must be good, end to end.
so...
i put my voltmeter across battery, i start car, i see 13.3 to 15vdc, alt is good.
no? , i see now, 12.2v. ALt is dead, (i didnt say bad) and battery is sightly discharged, 12.6v is charged. (key off, rested voltage)
This 12v tells me the ALT is shut down. only why is the question.

how can any charge system fail,
bad battery tops the list here, they LOVE to fail.
1: belt slips.
2: belt missing
3: bad alt.
4: bad wires to ALT . (corrosion on any wire or lug)
5: fuses blown , any listed below.:
your alt is not an ECU controlled, alt ,its 100% self contained

did you ever remove the ALT and blow the 100 amp fuseable link
the first step of any alt pul, is the pull the NEG, battery lug or BOOM.

im logged in to alldata.com so can you.

and what do i see.
a 5 wire ALT. one is the frame ground, so it must not be rusty or..... it fails. frame to engine block. no rust here.

wire L , yellow.goes to dash LEDs (alt failure idiot lamps) (this works)
wire. S white goes to ALT 5a fuse, is it blown?
wire :B B/G color, goes to the 100 amp link fuse. (blown>?)
wire IG Red-white, goes to a fuse marked 10A gauge.

i think the IG wire is the voltage sense wire.
no sense, no charge. I think the whole I/P dash cluster goes dead when this fuse blows.

The S wire is the boot strap voltage sense, it wakes up the regulator .
if open , the reg stays asleep, as does ALT.
Alternators can not self start, the regulator has boot strap device
that cures that. called self excitation. so this wire is critical.
All wires except the L wire is critical. in this case.

the B wire is the big wire, it charges the battery . 50amps or more..

any of the 5 paths open , kills the ALT dead.
The REG inside the ALT can also shut it down.
eg: battery bad, with huge cell resistances. total.
eg: overvoltge for any reasons. including attempts top run car with no battery, (dont ask)
eg: over current (battery cells 1 to 6 shorted) or 25 KC lamps added.
eg: over temperature shut down.

that is about it.







Dec 31, 2013 | 2003 Toyota Matrix

2 Answers

'93 buick century battery drain


unhook hot wire to alt at night if batt is up the next morning it is the alt

Jan 03, 2013 | 1993 Buick Century

2 Answers

Charges ok, battery was replaced, connections cleaned and painted,ran fine for almost three months, then battery went flat again, checked altenator clleaned and greased connections, van ran fine for any...


I would check and clean any wire and connection between the alt and the battery and all grounds. Also check and see if charging voltage is the same at the battery post as it is at the lug on the alt.

Feb 20, 2011 | Chevrolet Venture Cars & Trucks

1 Answer

Lead wire from left battery that goes to alternator makes the battery start smoking like its going to blow up. if I un plug alternator batteries will not charge. lite on dash says check gages.


Start the vech and take of the pos ternimal from battery and if it stays running means the alt is good but if it shuts down the alt may be U/S.Make sure everything is turned off.

Aug 15, 2010 | 2008 Dodge Ram Pickup 3500

1 Answer

1995 lincoln town car: batt lite is on


CHECK THE FUSES IN SIDE AND OUT SIDE IF THEY CHECK OUT GOOD HAVE THE ALT. CHECKED ONE MORE TIME JUST BECAUSE ITS NEW DON'T MEAN YOUR WERN'T SOLD A BAD ONE IT HAPPENS ALL THE TIME ALSO AT ONE TIME WHEN YOU PUT A NEW / REBUILT ALT ON A FORD THEY CAME WITH A NEW PIG TAIL FOR THE WIREING MAKE SURE THAT YOU DON'T HAVE TO REPLACE THE PIG TAIL FOR SOME RESON IF YOU DIDN'T REPLACE IT IT WOULD SHORT OUT THE NEW ALT.

Jan 03, 2009 | 1995 Lincoln Town Car

2 Answers

2001 cavalier codes


P0621 - indicates a failure in the alternator lamp curcuit.
P0304 - indicates a miss fire was detected in the #4 cylinder
U1040 - indicates a loss of communication with the ABS system
U1000 - Indicates a class 2 communication loss

None of those codes are relating to a transmission failure (P0700-P0702)

I would have a visual look at the transmission and verify that all electrical wires are connected and tight. Then I would have the transmission serviced if it hasn't been within the last 35,000 miles.

Have the trouble codes cleared and address the ones that return.

After that you may be looking at an internal transmission adjustment and/or repair.

Good luck.

Nov 24, 2008 | 2001 Chevrolet Cavalier

2 Answers

HELP


check for blown fuses& make sure the red wire to alt. is getting 12volts. also ford uses fusible links witch look like regular wires. usually you can tell by feeling the wire itself if it feels squishy and when you pull on it it stretches chances are its bad. try an ohm meter at each end no continuity no connection

Nov 01, 2008 | 1987 Ford F 250

1 Answer

F250 NEED HELP!!!


The only thing I could suggest is that if you bought a remanufactured alternater you may have gotten a bad one. It tends to be hit or miss with any remanufactured part.

Oct 31, 2008 | 1987 Ford F 250

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