alternator probs

I am having some alternator problems on my 86 lx (weber swap). Was driving last week when my oil pressure light came on, then a couple minutes later it went out. So I went on a roady and ended up getting towed home when the charging circuit failed(no battery light) and the battery died. next morning changed the alternator (fun). sure is nice with no vacuum lines in the way. went for a drive with the new alternator and all of a sudden the battery light comes on. alternator not charging. I tested the green plug that goes to the back of the alternator and there is no power to the black/yellow and the blue/white with the car running. I checked all the fuzes and they look good. Since the fuze for the alternator also runs the fuel pump Figure its something in between. Is there a relay somewhere?

Any ideas

Take a look at this thread of mine. It has charging system diagnostics in it, posts courtesy of lostforawhile. Tests are best made with a multi-meter. Test for voltage at the battery with the engine running. Should be between 13.5 and 14.8 volts roughly. Test resistance and continuity between positive terminal on the alternator and battery. Same with alternator casing and negative terminal. Should be under 1.0 ohm. This lets you know your getting good contact. When checking the wires to the fuse box from the alternator wiring harness, check for continuity and resistance between those wires and the fuses themselves too. Check to see if anything is grounding out by checking for continuty from all the wires to ground, including the choke heater. Also, try downloading the genuine repair manual from the WiKi if you do not have it already. It will help with electrical diagnostics.

Here is the thread...

https://www.3geez.com/forum/showthread.php?t=77572

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Originally Posted by hondaaccorddrew

Here is the thread...

https://www.3geez.com/forum/showthread.php?t=77572

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with the key on black/yellow should have voltage, white/green should have voltage regardless of key position , the blue/white wire also goes to the multi function box under the center of the dash, and to the emissions control box under the drivers seat, the voltage with the engine running acts as a status signal for those, one fuse is under the hood, thats for the white/green wire, the black yellow has voltage with the key on, it's fuse 1 inside of the car,

When I did the weber conversion I took the hot lead from the choke heater and put it to the weber electric choke. a couple days later I lost power to this connection so I hooked the electric choke up to a hot lead from the plug which went to the black box. then I lost power there as well so I hooked up to another ignition controlled hot lead at the same black box plug. There is no power at the black/yellow on the alternator plug, or the blue/white. all the fuzes are good. Do you think I fried the ecu. I didn't think it controlled anything after the weber swap. Can I just run an ignition controlled hot lead from the fuze box to the black yellow wire on the alternator to solve this mess or will it screw something up further
cheers
dummass

no continuity between no 1 fuse and bl/y wire at alternator connector

i think that electric choke may be bad and is drawing too much power causing failures in the fuses or the contacts in the circuit.
I'm trying to locate my wiring diagrams but you either have a blown fuse or part of the ignition switch may be burned up.
You could run a switched 12v to the alternator blk/yel but I'd leave that choke disconnected until you can verify that it is good.

thanks for the advice POS carb . I ran a temporary 12v to the bl/Y wire and the alternator began putting out 14.5v. now i just have to find a switched 12v without messing something else up. I tried a different multi function box and it still didn't give me power to the bl/Y wire. I wish I knew where the break is between the fuse box and the bl/Y at the alternator plug

If you have power at fuse #1 there is a broken wire between it and the alternator. The stock carb ECU will also quit working.

this might help but I like my old Mitchels book better
http://3geez.wiki-tv.com/manuals/198...g%20Manual.zip

When I say "ecu", it is technically an electronic control unit, even if it is basic, the carbed cars have one.

The BLK/YEL to the alternator comes from the ignition switch RUN to dash fuse #1, goes to a junction connector near the headlight retractor control unit just behind the dash fuse box. From there it splits to the alternator, charge warning lamp, and carb "ecu"

If you have power at the #1 fuse then the ignition switch is good. Check for power at the "ecu" under the seat. That wire is broken somewhere along the way to the alternator. If there is power at the ecu then the break is probably in the engine bay. If there is no power at the ecm check the junction by the headlight retractor controller

The keihin carb pre-heater plate ("efe heater", black "spacer" underneath the carb) gets its power from a relay (I think the relay is mounted to the ecu but I don't remember, it's been so long since I had one). It is triggered by ecu pin A4 (BLU) and gets power from engine bay fuse #24 (WHT/RED). Output at the relay is a WHT/YEL wire which turns into a solid WHT by the time it reaches the efe plate.

Now the choke heater is powered by a WHT/BLU wire coming off the alternator. The charge warning light in the dashboard is connected between this BLU/WHT on the alternator/choke heater and the infamous BLK/YEL. Now I must admit I am not sure on this next part, but based on the diagrams I am seeing it would appear that this WHT/BLU on the alternator gives 14V+ when it is running, and since the bulb has (or should have) 14v+ on the other leg from the BLK/YEL no power will flow and the light stays off, choke works, ecu gets its alternator signal at pin A13. If the alternator doesn't charge I guess the power starts flowing from the BLK/YEL, through the charge light, and grounds out through the choke heater and the ecu, or maybe even the alternator causing the light to illuminate. I have no ecu or choke but my battery light works so I dunno what to make of that other than it must ground through the alternator when the alternator isn't charging.


hope this helps

:blah:

Quote:

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Originally Posted by POS carb

If you have power at fuse #1 there is a broken wire between it and the alternator. The stock carb ECU will also quit working.

this might help but I like my old Mitchels book better
http://3geez.wiki-tv.com/manuals/198...g%20Manual.zip

When I say "ecu", it is technically an electronic control unit, even if it is basic, the carbed cars have one.

The BLK/YEL to the alternator comes from the ignition switch RUN to dash fuse #1, goes to a junction connector near the headlight retractor control unit just behind the dash fuse box. From there it splits to the alternator, charge warning lamp, and carb "ecu"

If you have power at the #1 fuse then the ignition switch is good. Check for power at the "ecu" under the seat. That wire is broken somewhere along the way to the alternator. If there is power at the ecu then the break is probably in the engine bay. If there is no power at the ecm check the junction by the headlight retractor controller

The keihin carb pre-heater plate ("efe heater", black "spacer" underneath the carb) gets its power from a relay (I think the relay is mounted to the ecu but I don't remember, it's been so long since I had one). It is triggered by ecu pin A4 (BLU) and gets power from engine bay fuse #24 (WHT/RED). Output at the relay is a WHT/YEL wire which turns into a solid WHT by the time it reaches the efe plate.

Now the choke heater is powered by a WHT/BLU wire coming off the alternator. The charge warning light in the dashboard is connected between this BLU/WHT on the alternator/choke heater and the infamous BLK/YEL. Now I must admit I am not sure on this next part, but based on the diagrams I am seeing it would appear that this WHT/BLU on the alternator gives 14V+ when it is running, and since the bulb has (or should have) 14v+ on the other leg from the BLK/YEL no power will flow and the light stays off, choke works, ecu gets its alternator signal at pin A13. If the alternator doesn't charge I guess the power starts flowing from the BLK/YEL, through the charge light, and grounds out through the choke heater and the ecu, or maybe even the alternator causing the light to illuminate. I have no ecu or choke but my battery light works so I dunno what to make of that other than it must ground through the alternator when the alternator isn't charging.


hope this helps

:blah:

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you are right on the white/blue the box under the dash also gets a positive voltage signal when the alternator is running
the carb preheater plate only comes on when the temp is below a certain degree, there's a timer control unit under the drivers seat

Quote:

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Originally Posted by dummass

thanks for the advice POS carb . I ran a temporary 12v to the bl/Y wire and the alternator began putting out 14.5v. now i just have to find a switched 12v without messing something else up. I tried a different multi function box and it still didn't give me power to the bl/Y wire. I wish I knew where the break is between the fuse box and the bl/Y at the alternator plug

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just a run a new wire. If its broke then its to old to be any good.

Also look into running a large guage wire from the big post of the alt DIRECTLY to the positive of your battery. A wire that would carry 80 amps should be the correct size.

if you have one bad wire chances are you have more then one. The load will go more thru the larger wire and less thru the older smaller ones.


wp




wp

you just need to follow the harness from the alternator to where it goes into the fender by the fuse box, it's pretty easy, just make up a new piece of harness and solder on the alternator plug from the alternator, it's probably burned or crimped somewhere, the wire generally doesn't go bad, something happens to the harness under the hood.

That is some great info. I ran a fused (20A) wire from the "auto cruise" fuse inside the car to the black/yellow at the alternator. I don't have cruise so I thought I would try it. I got some good charging happening now. The car is a bit of a rust bucket but I love driving it, it rides great on our questionable roads up here in central bc. I'm gonna check the power at the ecu, my two donor accords are automatics so I don't think the ecu's are gonna be transferable.

why do you need to transfer the ecu? it shouldn't affect the charging as far as it not working, if it's carbed the ecu simply uses the positive/negative at the blue/white wire as a reference

Hi. I was going to put a different ecu in the car to see if it would solve the problem of no power at the bl/Y wire. But if you say that it is not affected by the ecu then I'll go with that. It's running and charging so all's good

Quote:

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Originally Posted by dummass

Hi. I was going to put a different ecu in the car to see if it would solve the problem of no power at the bl/Y wire. But if you say that it is not affected by the ecu then I'll go with that. It's running and charging so all's good

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the black/yellow wire comes from the fuse box not the ecu. On a carbed car the ecu only reads the blue/white wire to determine if the engine is running