need help wiring an alternator

woodie9061 · #1 04-19-2006, 12:10 AM

Over the weekend I had to jump start my 1991 Dodge Dakota. After doing so the alternator stopped charging the battery. while replacing the alternator I noticed that the wiring attached to the little black box on the alternator had been cut and spliced and taped together. I dont know if it was wired right from the begining. there are two small wires attached to the black box.
one is green,
the other is blue

they have been cut and spliced . there is also two larger black wires attached to the box. I beleive one is a ground wire and the other is a power wire but i'm not sure

Can someone tell me how it is suppose the be wired.

Also when the alternator went out the RPM gage went in to the red, and has not moved since.

Can the RPM gage be reset?

dodgerules86 · #2 04-19-2006, 06:07 AM

the large solid black wire is from the battery.
the large black with white stripe wire goes to your ground
the small dark green wire goes to the Powertrain Control Module
the small dark blue wire is your Automatic Shut Down Relay Output

woodie9061 · #3 04-19-2006, 07:32 PM

Thank you Dodgerules86 you were very helpful

dodgerules86 · #4 04-19-2006, 09:14 PM

did you find out how to reset your tachometer?

woodie9061 · #5 04-20-2006, 12:02 AM

No. I still need help with the tachometer problem.

dodgerules86 · #6 04-20-2006, 04:39 AM

well, youve got a 91 and ive got a 96, so.. just a warning
before you do this, just check your fuses (the normal fuse block and also the power distributon center under the hood)
you need to get to the left instrument cluster connector. in order to go this, you need to take off the cluster bezel and the instrument panel, here is a link, just read my post. you are interested in the left, or red, connector.
Check for battery voltage (remember to reconnect the battery for this) at the Fused B(+) cavity (red wire between a gray and light blue wire and a orange OR light green and red wire [depending on abs system.. i never did check my connector, and i dont have abs, but i guess the wires might be there). if not ok repair open circuit (looks like the power comes thru the 20A fuse 6 which gets its power from the 50A fuse G in the power distribution center)

with engine running, check for tach signal at tach signal circuit cavity of PCM connector C (gray) the wire going to this cavity is gray and light blue (cavity 31; between a violet and brown wire and a white and light green wire) frequency ranges are: @ 2000 rpm 66.7hz; @ 5000 rpm 166.7hz i dont know anything about fequency and electricty, so i dont know if it will like be putting off voltage or whatever. but, if its good, contiune, if not, you need to test the PCM
disconnect the negative battery cable. unplug PCM connector.
probe tach signal circut cavity (gray and light blue wire between the fused b+ red wire and a black ground wire) of left (red) cluster connector. check for continuity to a good ground. there should be no continuity. if ok, continue, if not, repair short circut.
check for continuity between tach signal circuit cavity of left cluster connector (the gray and light blue wire) and pcm connector c (the gray connector, gray and light blue wire) there should be continuity. if ok, go on, if not, repair.
the next, and final, step is to replace the tachometer drive module with a known good, and, if that doesnt work, replace the faulty tachometer.

like i said, if this info doesnt match up to your truck, im sorry.. i tried. hope its just a fuse or something before you practically test every wire in the truck, lol. let me know if this actually works.

woodie9061 · #7 04-20-2006, 06:43 PM

Thanx again Dodgerrules86.

I'll Let you know how it went in a few days. we had lot's of rain here in the Dallas area. and the truck is in the back yard.