LFM620 Posted March 28, 2017 Report Share Posted March 28, 2017 Hey guys I have a problem with my 1973 Datsun 620 I bought it and pervious owner put a z24 engine in it and those have a internally regulated alternator how do I wire it up to the 620 harness my ground is on the motor mount I think that's a bad place have the power going to the starter post I need to know where I need grounds and how to wire the alternator to the 620 harness it completely drains the battery right now. Quote Link to comment
datzenmike Posted March 28, 2017 Report Share Posted March 28, 2017 The ground on the Z series engines is on the intake near the thermostat. Any good point will do. It shouls also have a good ground to the body sheet metal. Quote Link to comment
DanielC Posted March 28, 2017 Report Share Posted March 28, 2017 The alternator frame (case) needs to ground to the battery, through the negative battery cable. The alternator frame should also ground to the cab sheet metal. The following is based on what I know about 521 trucks, but like the 521's, the 1973 620 still had an external voltage regulator. One of the ground wires on a 521 went from the alternator frame to one of the bolts holding the voltage to the inner fender. This ground wire is very important, without it the cab may try to ground through the throttle cable, and destroy it. Even if you are using an internally regulated alternator, this ground wire must remain in place. Your alternator may also have bad diodes in it. Bolt it to the engine, hook up the ground wires only. Connect a test light to the positive output of the alternator, with the engine off, and no other wires than ground wires on the alternator. Touch the other end of the test light to the positive battery terminal. If the light lights up, the alternator diodes are bad. Quote Link to comment
datzenmike Posted March 28, 2017 Report Share Posted March 28, 2017 Pull either battery cable and connect a test lamp between them. If it comes on there is something ON drawing power. Pull the fuses out one at a time... if it goes out that fuse circuit has a draw on it. For example if your horns were on the owner may have pulled the wires off them but the relay is still on all the time and will drain the battery over the weekend. Are the brake lights stuck on? Unplug the alternator... if it goes out a diode may be bad. Quote Link to comment
banzai510(hainz) Posted March 28, 2017 Report Share Posted March 28, 2017 wonder if its the choke relay since its a 73 and has auto choke wiring the car wont know what motor is in there but it will know if a a IR or external volt reg. on 510s when a IR alt is installed on a auto choke car the autochoke relay needs to be disconnected. Assume same with the trucks Quote Link to comment
banzai510(hainz) Posted March 28, 2017 Report Share Posted March 28, 2017 do what Mike said put a test light inbetween batter cable and when light is ON then find the choke relay and disconnect. if light out then you found the proplem. Make sure dorr closed so dome light or buzser don't trick the test light ot come on Quote Link to comment
datzenmike Posted March 28, 2017 Report Share Posted March 28, 2017 Yes if the regulator was removed when converting to internal regulator the choke relay has to be removed/unplugged. Just jump power from the idle cut solenoid... this is what I did. Quote Link to comment
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