1987 alternator wiring

[dirtymike]

My 87 ranger 2.9 4x4 alternator went out. It had been replaced once before by me PN 7725-2. Took the alternator to Autozone where i had got it years ago. Seems that all the alternators have been modified ,changed or deleted. One remains in place for all (AZ DL7725-2). After cutting the pig off and soldering in the two black wires i noticed i have no place to connect the white wire that comes off the new alternator(DL7725-2). Is this something that is in the archives? I haven't had any luck so far. Any help is appreciated. Dirty

 

[RonD]

Look here: https://contentinfo.autozone.com/znetcs/psb/en_US/2/0/86/tt-545.pdf

You have a Battery light so would use the UPPER diagram which show the White wire(S) connected to the (STA), other other terminal, next to B+

If you don't have a Battery Light then no white wire would be used, well you would use it for Key On 12v, and not use the "I" connection on voltage regulator

 

[dirtymike]

Yes sir, it is the diagram without indicator lamp. The alternators they keep ordering is the one with indicator lamp wiring. I guess ill feed this info to the local AZ and see if they know. Ill be back with a answer. Thanks RonD, figured you would answer. Hows the great white North.

 

[RonD]

Things are WET

Same alternator, just hooked up to suit the vehicle wiring

 

[dirtymike]

Same Alternator? I hooked the first one up and nothing. Of course the white wire coming out of the Alternator was left not connected. No sure where to connect it to.(Being the one on the bottom diagram on TT-545). If this can be accomplished where do i place the white wire? Picking up the replacement that has a connector not a pigtail today. Ill post results. Think ill start with a different parts store next time, Thanks RonD Dirty

 

[dirtymike]

Picked up the reman autozone (7725-2) alternator with no indicator lamp. No DL in front of the part number. Seems these are harder to find and the others with a pigtail (DL7725-2) are given in place. Confused on how others have have accomplished the wiring task to get them to charge. Autozone cant even test them(DL7725-2).

 

[RonD]

In a vehicle with no indicator light the white wire is connected to key ON 12v as shown in lower diagram

Its the ON/OFF switch for alternator in that type of wiring setup
Alternators need to be turned off when not in use or they will drain the battery pretty quickly, so all alternators have an on/off switch, key on 12v power

With one exception, One Wire Alternator
There is literally just one wire connected to battery positive(with an in line fuse)
These have an internal RPM switch, when minimum RPM is reached, the switch closes and 12v is sent to internal voltage regulator which turns on the alternators charging ability
These are not used by car makers because they often won't charge at idle RPMs under 1,000

 

[dirtymike]

Thanks RonD for your quick response and the TT 545. Think the man behind the counter was a bit confused. Had to solder in a new connector. (duralast pn 232) with 3 leads, 2 black with brown strip, 1 white with black strip. The white with black was capped off. It had 7.4vdc. Charges at idle, 13-14.