show me a picture of your gauge cluster...
...if you DO NOT get a charge light on at key on, i found your issue, youre not exciting your alternator. To excite your alternator you need to provide resisted 12 volts to the L terminal on the alternator 4 wire plug (they are labled on the alternator or the plug or both) You resist it by using a 194 bulb so not to provide full 12v, (that is bad for the regulator) If you instantly start charging by doing this, your issue is 100% the light being gone
Hello
@Reluctanse,
@AuroraGirl ,
@1990Z71Swede,
@Erik the Awful, and
@GoToGuy have all posted
really solid troubleshooting info on all this. In order to tie all this together (for future
reference by others) I'm going to attach some stuff to visually support what they've
already shared.
In the 1st attachment I've pulled what should be your instrument cluster out of the
'99 FSM. (Isn't it the same as the one in my '99?
'99 C2500 gauges) When you first
turn the key to the RUN position (but the engine hasn't started yet), that Battery
icon should be illuminated, and then goes off once the engine has started & charging
has commenced. As AuroraGirl stated above, if you
never see this battery icon
illuminated on your truck, then this is the proverbial smoking bulb we've been
looking for. :0)
In the 2nd attachment I'm building on GoToGuy's schematic in reply #15 above.
His detailed schematic is in the center of this Big Picture view of the charging
system, all the way from the power source (Fuse 4, 'GAUGES') through the
"Charge Warning Indicator" instrument panel light, and finally excitation pin L
on the 'Generator'.
NOTE: I include this on the off chance that the bulb for the Battery icon doesn't ever
illuminate *but* the bulb is found to still be good? (ie: marginal wiring path not
allowing enough current to illuminate good bulb...and also making it hard for a
cold alternator to excite?)
In the 3rd attachment is this circuit's Theory of Operation to go along with
the big picture schematic. I put a small box around their statement that
the alternator does get going via a powered bulb connected to pin L. (Lamp)
In the 4th attachment are the pinouts for 3 different connectors. Looks to
me that the gas jobs only have the Lamp wire, whereas the Diesels add a
second connection to allow the alternator ('generator') to provide the
'Tachometer' signal to the instrument cluster.
And for those who found the terse circuit description in the FSM only whetted
their appetite for knowledge about getting alternators excited about working
right away, I found this article from the Motor website to be a good read.
(
P-L-I-S Alternator troubleshooting strategies)
To summarize, IF the 'Charge Warning Indicator' bulb is working properly, then
removing the Alternator (in order to be able to test it while cold/broken) at your
favorite parts store that offers the free service is your best bet.
On the other hand, if the Battery Icon isn't illuminating, then we need to get that
working (hopefully nothing more than a bulb swap) and *then* see if the alternator
starts working 'right now' like it should.
Best of luck. Looking forward to reading all about what you discover.
Cheers --
