techartisan

84 944 na
No factory alarm

I started chasing a no start......
dead battery...replaced
starter making bad noises...and not turning....was seized on removal....replaced.

Finally starting.....

but battery light FULL on lit....does not go out.
Previously Ive had issues with it staying on quite dimly lit for a few minutes...but its fully lit now.
Now I know everyone is going to tell me what a bad idea it is to do....but when I flip the battery cut out switch while the engine is running it shut down....yeah I know "could fry the....." but anyway...its clearly not charging.

So I pulled the alternator...
Autozone tested it....says its fine.
DAMN! SO whats wrong?

I have the battery out....alternator is still out.
Tested the fat red wire....showing continuity with the positive battery cable.
The exciter wire is showing continuity to ground? even with the key turned....
I traced the wire through connector t21 and t1a...the wire is fine that far....the fuse box side of t1a is showing continuity with ground though. not really sure where it goes or what it does past here the schematic isnt really clear in that regard.

Havent tested to see what it does with the battery in yet. But is this normal though, a grounded exciter wire when disconnected?

At what point does the wire become excited?
first turn of the key? yes
or starter engage? nope
Is it a function of the ignition switch or the dme? ignition switch for the win

As I now understand it, An ignition switched power line is coupled to one side of the alternator/battery bulb in the dash....the exciter wire finds ground through the inactive field coil....but once the coil is active and producing current there is no ground in circuit so the bulb extinguishes

Im putting the alternator back in tomorrow morning so any advice on things to check first would be appreciated.

techartisan

Okay so to bump this up....
and show some progress....

After some more reading last night I now understand that there is positive voltage routed through the dash light and into the exciter wire. When the alternator is NOT generating current the exciter wire finds ground through the field coil allowing the dash light to be lit. Once its producing sufficient current there is no ground for the lamp and it goes out....positive...positive...no light.

So with the alternator not in the car....and the exciter wire free from connection there should be NO ground....and NO light.

If the light illuminates with the alternator out....or the exciter wire merely disconnected...there is a short somewhere. The t21 connector behind the brake booster and the t1a near the fuse box are good points to check for shorts by testing continuity with ground. when I tested the t1a towards the fusebox It showed continuity with ground....but the other way was clear....I thought this was indicative of a short but it seems to be working fine now so dunno.
As I read, this would not only prevent excitation, but also prevent self excitation from occurring (@~3krpm), much in the same way the alarm module grounding the exciter does.

So my mission for today....
1.reinstall alternator.
2.Start car with T1a disconnected. If the alternator light is lit my theory is confirmed. nope light was outProceed to step 3...else goto step 5
3. Dig into the dash, trace and replace the wire from bulb to connector....start car again if light is still staying lit goto step 5 if not....
4. Rejoice in my success. Post triumphantly that I have once again bested my cars demons. Call it a day.

5. Scratch head in bewilderment...post again hoping someone else knows whats wrong put it all back together again and it works fine....head well scratched

techartisan

WELL.....
I put the battery in....turned the key...and no alternator/battery light....grounded the exciter...light illuminates. Multimetered the exciter wire with the key turned (no alternator in place) and got 12v...hmm

So I put the alternator back in....started the car...no light at key...no light at start...no light while running....battery voltage dropping....then I realized....I secured the alternator....I tensioned the belt....I didnt connect its wires this time DUH

So I connect the wires....turn the key....alternator/battery light is lit.
start the car....light goes out.
whip out the multimeter...14V

So basically.....my car really wanted me to pay for months of inactivity by removing and reinstalling parts

Oh I did manage to break the vacuum hose on the brake booster check valve....so Ill be watching my mailbox for that now.

I imagine one of several things happened....either I cleaned something along the way that really needed it...I tightened something that was loose....or maybe...having the alternator bench tested "woke it back up" somehow.

Im not sure if this thread will help anyone with a similar problem...

Car iss probably playing an april fools prank on me....tomorrow it probably wont run again. LOL

kinda5150

she probably just wanted some attention mine is craving entirely too much attention these days...

techartisan

well I gave her a bit of extra love today...
fixed the parking brake....
Figured since I had one seat out....pulled the passenger seat as well....
gave her the deep underseat vacuuming.
armorall'd the interior
gave the seats a deep cleaning and reinstalled
restocked and reorganized the tools I keep in the car

still need to clean the interior glass and give the outside a good wipedown....but its a good day for it. First blue sky Ive seen since I hit portland a week ago....should get her nice and shiny for tomorrows rain LOL.

monteolsen1

Ahhh, a true Oregonian! (Like me.) ;-)

techartisan

dunno about true oregonian just yet....
Ive only been here a week. Im really hoping to pass the OR DEQ tomorrow....followed by plates and a license...which would get me a bit closer to Oregononian LOL
I passed CAlifornias CARB a year and a half ago with flying colors....
but I seem to HAVE developed an odd noise I suspect to be chunky catalytic disorder.....so we will see.apparently closer to death than I imagined.

After giving her a good cleaning I pulled the front drivers tire to see what the story was with my intermittent speedo....turns out to be a simple fix....when I put the new cable in last year I seem to have forgotten to adjust the rubber grommet that keeps the line pulled tight...so a hard left, followed by a hard right would allow the cable and center hub dish to extend past the grooves.....few bumps and tuns later and it would reengage. LOL Now if i can just get the horn honking on command....instead of randomly on its own...LOL silly cars.

techartisan

So I drove over the the testing site.....car ran great...passed with flying colors
passing is hc 220ppm, co 1%
I scored a hc 71ppm , co0.5784%

Drove to the DMV got plates...headed to work....worked my 8...drove home....
about half way home I start to lose power....cant rev over 4000
next day I leave for work....new job...cant miss work.....and I drive all the way there under 3500rpm....not by choice.
Unplug the TPS.....no effect..plug it back in....
Unplig the O2 sensor......no help
Unplug the afm......no improvement

So given my limited time and need to get it running quick I break down and turn to a mechanic....Motor Sports International is about a mile and a half from my house....so I decide to drive there....at about 1500 rpm...all the power I have left LOL

Catalytic converter is shot.....Im just hoping when they replace it monday thats the only problem. Shop bills can get up there pretty quick.

Pretty interesting that you can pass oregon emissions with a cat near death.

944Ross

Had that happen on the cat on a Fiero GT I used to own; the monolith wore into a ball that rolled into the outlet and plugged it on left turns. Get out, kick it, and I'd be good til the next left turn.

Congrats on your very thorough electrical diagnosis!