89tracerman

i installed another engine in my 87 N/A last week and just right now i nothiced that i didnt pulg in the wire harness behing the alternator, i have driven the car for about 100 miles and the only thing i have noticed is that the volts gauge dosent work. do those wires have any thing to do with recharging the battery or are they just for the gauge?
Btw i cant seem to find the wires any where what will happen if i leave it unplugged?
thanks

WAYNE88N/A

They are your field excitation wires, for one- responsible for telling the voltage reg what the initial system voltage is so that it can produce a voltage a calibrated amount above that to safely recharge the batt while adjusting the current output for the various electrical loads on the system, among other things...

You're basically running in "fail-safe" mode- the rpms of the alt determines the charging voltage to a large extent. Luckily I think the internal voltage reg prevents the alt from going haywire even though it has no idea what the base system voltages are. You should have noticed a large fluctuation on your voltage gauge while driving, especially between idle speeds and highway cruising...

I'd fix it, if it was me

89tracerman

the volts gauge dosent work, and i cant find the plug.
how could i fix it?
thanks

WAYNE88N/A

Hmm, absent the entire plug, I'd say you're going to have to run new wiring, using the terminations given in the FSM wiring manual...

IIRC, one of them comes from the ignition switch, and the other comes from the alternator warning light relay in the CPU.

I would think that even if the plug is missing, the old wiring should still be in or near the harness back there behind the alt. Remove the alt and do some searching...

I don't have the schematics with me now, so maybe someone like Hailers can get on and tell you which wire goes to which terminal (there should be a black/white wire and a white/black)...

Man, you really need to get some form of a voltmeter in the car...