alt swap, now power drains

[q-tip]

Tried to find a solution for this but my searching of the site yeilded no results for my situation.I did the ka hard body alternator swap on my 620, works great, two problems.

 

1. Charge light on the dash doesn't work when I turn the key on.

2. Have a major power drain, if I unplug the alternator from the "T" plug for the stock one the drain stops.

 

I spliced the white to yellow and w/r to w/b on the external regulator plug. Plugged harness for new alternator into factory plugs. Hooked ground wire to body of alternator

 

Never had a power drain before the swap

[datzenmike]

There are two wires to the alternator plug so how did you gigure out which one goes where??? The 620 plug won't fit the KA alt so did you guess?

 

This makes more sense now. The charge light is mysteriously not working and also there is a drain. I suspect you have the two wires to the plug reversed.

 

The KA alt plug should be marked L and S terminals.

 

 

The L on the alt. should have the Yellow wire on the 620 harness. This is the charge lamp in the dash.

 

The S on the alt. should have the White/Black stripe wire from the 620 harness.

[Draker]

Also an bad alternator itself can cause a drain. But mike is probably right.

[q-tip]

Wires are correct, the charge light stopped working before I swapped the alternator now that I really think about it. I'm just stumped. I also thought bad alternator as well. I did notice that when I hooked the battery back up the heater a/c relay kicks on, could it be something there?

[RMS]

correct me if I am wrong but doesn't the field wire need to be connected to a 10ohm resister such as the charge light or the diodes will fry causing drain back?

[q-tip]

The bulb is still good in the dash, I used the little green plastic fuse from the hardbody harness that's on the field wire, that's not blown either

[datzenmike]

You have the choke heater relay disconnected? Converting to internal reg alternator will require joining two pair of wires and this will permanently turn the choke heater relay on. I think this is mentioned. I had the same problem. Remove or disconnect the relay and wire the choke heater (red wire) on the carb to the idle cut solenoid (blue wire) right beside it. 

[q-tip]

That must be my issue, I'm using that wire to run the choke on the Webber, I will check for a switched power to run it. Will report on my findings

[izzo]

also, auto choke relay must be un plugged if you have one when you do the conversion.

 

edit tl;dr looks like its been said lolz

[banzai510(hainz)]

most 510s under the fuse box there is a blue 12volt wire (air con) this is switchable .

[q-tip]

Its in a 620, checked all of the wired that once went to the stock carb, none of them have power unless the key is on. The truck sat in my garage for 2 months and fired right up. The only thing that has changed it the new alternator.

 

Will try unplugging the a.c. heater relay tomorrow, the yellow and white with blue stripe both go the this relay and it splits a lot from there, seems important to me

[q-tip]

Relay is unplugged, time will tell if I still have a draw somewhere

[banzai510(hainz)]

Relay is unplugged, time will tell if I still have a draw somewhere?????

ck it now!!!!!!

 

watch this about 50 secs into.

Thats how you ck for a drain, make sure everything is OFF.

 

[q-tip]

That's a new piece of knowledge for me, will get the resistor and some clips tomorrow

[banzai510(hainz)]

YOu dont need the resisitor.

just do the first part.

test light inbetween the battery post and the bat cable. if light On then you got a drain.

Your system is not new enought to use the resisitor set up as he describes

[q-tip]

I was thinking in terms of accessories like the radio drawing, im just curious how big of a draw I have. Its not like a 620 has a fuse for every thing either

[DanielC]

These old trucks, with out an engine computer that has to draw something to keep some computer settings memorized should have ZERO power drain when they are off.  If you put a modern radio that needs constant power to remember the preset stations, that will be a slight drain.

 

The "L" terminal on the alternator is for the charge light.  The charge light gets power froM the ignition switch, and the alternator grounds this light when it is not turning.  The alternator also uses this current to initially start the alternator charging.  once the alternator is charging, it really does not need this anymore.

 

The "S" terminal is used by the alternator to "Sense" the battery voltage.  THIS IS NOT THE ALTERNATOR VOLTAGE, the alternator voltage will be slightly higher than battery voltage to make up for losses in the wiring between the alternator, and the battery.  Connecting this wire directly to the battery, or leaving it hot all the time CAN be a current draw on the battery, or not, it depends on the internal wiring of the alternator.  Connecting or jumping the "S" terminal to the alternator output terminal will not give the alternator the battery voltage, and the battery may end up being slightly under charged all the time.

[q-tip]

Did the test light draw test, with every fuse out of the fuse block the alternator unplugged the radio in plugged there is still a draw, I am truly dumfounded

[datzenmike]

Disconnect the White/Red power wire on the alternator. Perhaps a bad diode.

 

Unplug the ignition switch.

[q-tip]

I tried unplugginf the ignition switch, the white/red is about the only thing I didn't disconnect

[q-tip]

Something strange I forgot to mention. When I disconnected the alternator and then connected the test light to test the light would come on brighter than normal then go out and come on like it had on every time before

[banzai510(hainz)]

since you have a KA swap maybe its on that side of the circut

[q-tip]

Just the alternator is from a ka, the rest of the truck is bone stock eccept for ei and a weber and never been torn into.

[datzenmike]

Just to be sure....

 

Old external regulator is disconnected?

 

Choke heater relay is disconnected?

[q-tip]

External regulator is disconnected, plug used to splice wires, choke relay also disconnected. I will try pulling the main wire off the alternator tomorrow when I have time to see if the alternator is just bad