Help! Serious Elec Problem

[rb6667]

I replaced my alternator with a rebuilt Bosch alternator today.  Hooked the battery back up and smoke started pouring out of the back of alternator.  I quickly pulled the battery cable off and the smoke stopped.  Now i have now power anywhere in the car.  Nothing!  I traced the wires that go to the alternator back to the junction block that mounts on the oil pan it it looks OK.  I next traced with wires that go the solenoid and the starter and they look OK.  Checked all fuses they are look good.

Where would you look next? 

Thanks much,

RB6667

[Larry & Norma]

Original alternators have separate voltage regulators, did you maybe use one
with built in regulator but not change the wiring?
Just a thought.

[rb6667]

Thanks for the reply.  This car had been previously converted to an internal regulated alternator at some time in the past.  The alternator was not charging so I replaced it with a rebuilt Bosch alternator.  Replaced it with the same part #.  Hooked the wires back up just as they were removed from the original alternator.  They were numbered before I removed them so I would make sure they went back on the new part exactly the same way. 

Wire marked 1 went into the far left terminal.  Wire 2 went into the center terminal, and 3 on the far right terminal.  As mentioned, as soon as the battery was hooked back up, smoke poured out of the back of the alternator.  If you look closely you can see wire # 2 was the one that got burned. 

Curiously wire # 1 had 2 wires that were not connected to the terminal but were inside the shrink wrap.

I am trying to figure out why I have no power in the car, and suspect something got fried elsewhere.  Hopeful a member can tell me what to check and in what sequence.

Thanks very much,

RB6667


 

[rb6667]

Additional information.  I got out my test light and have power going to the solenoid positive starter lead.  Next I checked the elec block mounted on the oil pan (Picture attached, Thanks 280SE guy)
I have power at the large screw terminal but nothing on the 2 other smaller terminals.  No power at all to the fuse box with the key on or off.

If this box is bad (Shorted) would that explain no power anywhere in the car?

Thanks,

RB6667

[Larry & Norma]

According to the wiring diagram there should be 2 wires on B+ of the alternator,
one from the battery and one going to the light/ignition switch etc. So with these wires
disconnected and separated you will not get any power anywhere except the starter.
See the diagram in the technical manual.

[Larry & Norma]

I would think the unused wires in the shrink wrap were the original external
voltage regulator wires.

[rb6667]

I checked the wires at the alternator.  I do have power at the wire marked # 2  (The one that got burned) nothing on the other 2 wires.  Am I understanding that power comes into the alternator on wire # 2, and goes out to power the rest of car on wire # 3 ?

Thanks much.

RB6667

[Larry & Norma]

I would suggest that wire coming from the battery should go to the 'B +' terminal, the one on the right in your picture
of the alternator.
Is it possible you muddled these up?

1. You may have just shorted the battery to ground, the smoke coming from melting insulation, the alternator would be ok.
2. You may have fried the alternator, need to get it checked.
3. May be a bad alternator, needs changing.

I suggest tracing the wires back, the one from the battery goes to 'B+'

[rb6667]

I have no doubt that this new alternator is toast!  Smoke poured out of the back after the battery was connected like it was under pressure.  I guess it is possible that the wrong wire was placed on the wrong terminal .  I do see that the far right terminal on the alternator is marked B+.  The wire that got fried was placed on the center terminal (this is the wire that has power on it)  The center large terminal has no markings that I can see.

If the wire that got fired is hot when the battery is connected, that must be the one coming from the battery correct?

Thanks Larry

[Larry & Norma]

Yes I would agree with that. If you have a meter with ohms (resistance) then you
can double check the wire through from the battery to B+ wire (battery disconnected)

Can't quite work out where the other wire taking B+ to the light/ignition switch is?

[rb6667]

I do have an ohm meter and a check revealed that wire #2(The one that has power on it, and the one that got burned) shows 001-003 resistance.  The other wires going to the alternator show nothing.  To confirm, I placed one lead on the subject alternator wire and the other end to the positive battery cable that had been disconnected from the battery.

So in summary, if the hot lead goes to B+ the other large wire must go to the other terminal (Middle One that is not marked on the Alternator)

Maybe someone can chime in to confirm if Larry and I are on the right track.

As a side note, I do have the correct alternator terminal that I plan to splice into the harness once all this is sorted out.

Many thanks,

RB6667

[rb6667]

Well, I might be getting somewhere now.  A close examination and a couple of pictures show that the wires were installed back onto the new alternator in the same sequence that they were removed.   I was pretty confident that I did not goof on the installation sequence and the pictures confirm this.  

Note the length of the black shrink wrap on both of the thick red wires.  One is longer than the other.  The picture showing the alternator with the wires connected was taken PRIOR to removing and numbering them.

The one that burned was on the center terminal.  This is the wire that has power on it when the battery is connected.  So here is my question:  The far right terminal is marked B+ on the alternator.  No marking on the center terminal  According to several sources ( Larry's advise and a wiring diagram) power should be on that far right terminal marked B+

The center terminal has no markings on the alternator.  Does it matter which wire goes where?  Are they connected to each other inside the alternator?

Now, with all this said, please remember that the original alternator was not charging, and may have installed incorrectly before I got this car.

Advise most appreciated.

RB6667

[garymand]

I have wondered about how this conversion is wired.  This is a good time to figure it out.  I can tell you what I know, and maybe we can deduce what’s right.  I'm sure about B+ and D-, pretty sure about D+, and not sure about DF.

What we know:  I see in your blue tape picture the brown and black are cut (unused) and taped to the red/blue  #1.  That’s good, they aren’t needed.  I know the Red/blue went to the regulator where it is jumpered to the blue wire and covered with shrink sleeve.  That’s good too, that wire goes to D+ and the dash charging light. Unfortunately, #2 is a problem, I cannot see the color of the plastic insulation on the #2 under the red cotton covering.  #3 looks to be solid Red.  We see D+ and B+ terminals marked on the alternator housing and now we know D+.  And we know something about B+.

I have the diagram for the original.  The original had a B+.  B+ is one of 3 outputs of the alternator, one goes to ground, one (B+) goes to the battery and one (D+) goes to the dash light.  The dash light is the red wire jumpered to the red/blue wire at the regulator connector and continues to the D+ at the alternator. 

The third output is B+ to charge the battery and supply voltage w/motor running.  It goes directly to the starter, battery +12, and the ignition switch.  This is a big red wire.  You appear to have 2 big reds.  Find which big red wire it is with your voltmeter.  Test for +12 volts from the battery.   One of those two red wires (2 or 3) is the B+ from the battery.   The one with 12 volts on it is B+.  My diagram shows 2 reds going to B+, which bothers me a bit because you have 2 red wires.  You need to see where the other red one goes.  B+ goes to the terminal block on the oil pan then to the starter then to the battery.  It also goes to the ignition switch and light switch as the battery +12 volts.  I think those are the other red wires in your terminal block picture (nice and clean). 
   
As shown on the alternator, the small connector on the left is D+, the red/blue wire is jumpered to the blue wire at your regulator and shrink sleeved.  You can check that the red/blue strip wire (#1 on blue tape goes to the regulator, for continuity with your ohmmeter by pushing a pin into the insulation at that connection.   And you can find B+, one of the two reds.

You need to verify where the other red wire #2 goes.

 The center connector on the new alternator is uncertain.  And, the original had a D-.  It is ground.  It is was Brown and you test it with your ohmmeter to chassis ground =0 ohms, short to ground.  Is it possible the other red wire goes to ground?   It appears to me you connected the wires as they should have been, but the middle one melted the connector and insolation.   My guess in the dark is the new alternator had a problem.  It can’t be the same as the old one, if you didn’t move any of your other connections. 

Does someone have the circuit for the new alternator?

[rb6667]

Hello Gary, Thanks for the reply.  The wire that got toasted # 2 is hot when the battery is connected.  The other red wire # 3, has no power on it when the battery cable is connected.  Al Lieffring tells me that both of the Large terminals at the alternator are both B+ terminals, and that they are connected to each other inside the alternator.  Given that, it appears that it really does not make any difference which wire goes where(the 2 red ones) as long as they are attached to the 2 large terminals at the alternator.

If I am following your guidance correctly, that means we have everything accounted for except for a ground wire???

Getting close I hope. 

Thanks again.
 
RB6667




 


   

[garymand]

If #2 goes to the battery, then we know it should go to B+ and we know B+ is the right terminal.  If you are skilled with an ohm meter and at measuring diodes or very low resistances, you should verify where the middle terminal goes.  If it were me, I would not hesitate to take the regulator/brush assembly off, open up the back of the alternator, and see where ithe center terminal goes and verify nothing is obviously amiss inside.  It is easy to reassemble. 

I'm very concerned that the center terminal is grounded.  I'm also concerned you didn't say where #3 goes and when #2 is hot.
If the #2 is hot with the ignition switch off, you would get a nasty spark and heat as soon as you touched the #2 to the center terminal, but you would not if you connect it to B+, becasue the diodes isolate the B+ from ground when stopped.  (Hope you understand diodes)
If #2 is hot only with the ignition switch on, then you don't get a spark or heat when you connect the wire to the center terminal with the ingition off.  But when you tun the ignition on, then you get the meltdown.  But when #2 is hot w/ign/on it is fine connected to B+.  Again because of the polatity of the internal diodes. 

So, When is #2 hot?  Ig on or Ig off?    and  Where does #3 go?    and where does the center terminal go?  (Ithink it might be ground)

[rb6667]

Thanks Gary.  PM sent

[garymand]

I found your original thread.  the other side of the dash bulb goes to ignition switched +Battery (+B). 

So, bottom line rb6667 you can test if your dash light is good simply by grounding the small red w/black stripe wire at the alternator.  That is with the ignition switch on.  The other side of the light goes to the ignition switch and then to the battery.  So if the light is there, and good, just turn on the ignition and ground the wire we have been labeling D+, the small red w/blue stripe.

[rb6667]

Got another Bosch Alternator installed today.  Based on all the most informative advise from Gary, Larry, and Al,  (Many thanks Guys)  I think we figured things out.  Made a few changes on how this was wired at the alternator.  The hot lead from the battery now goes to the far right terminal marked B+.  The other large red lead now is installed on the center terminal.  The thin blue wire goes to the far left terminal marked D+.  Simply put, the 2 red leads are now reversed from the way they were originally installed on the non working alternator.

Well, the moment of truth.......hooked the battery back up and no smoke this time Whew!   I now have 12.12 volts across the battery terminals with the engine running.  Still not what I would like to see, but an improvement over the 10 volts with the old alternator.  Alternator warning light is still not working.  Next step will be to ground the D+ terminal and see if the light works then.  If not, I'll replace the bulb. 

 Question:  Any of you have an easy way of replacing that bulb without taking half the dash apart?  Can I access it through the radio opening?

Again, Thank You all for your help on this situation. Merry Christmas!


 
 
 

[al_lieffring]

I would recommend doing a test before you go to the trouble of taking out the center instrument cluster. Test the alternator by unplugging the D+ terminal then connect the clamp end of a test lamp to the positive battery cable and also have a voltage meter connected to the battery terminals.

Next start up the motor, then hold the point end of the test lamp to the B+ spade on the alternator. this should excite the field and the voltage should jump up to around 13 volts. and the test lamp should be off.

If this works then tear apart the dash board and replace the indicator bulb.

Sorry there is no way to just sneak in a bulb without the removal of the instruments.

Al

[al_lieffring]

regarding your letter to my personal E-mail/

Your test procedure is wrong for this alternator, Connecting the blue/red wire to ground will not excite the field to make the alternator charge.

You should take a test lamp, with the clamp end connected to the + battery post, and touch the point end of the test lamp to the D+ on the alternator, Because you have already put the plug together look for the plug where the external voltage reg. was originally mounted on the right side fender well, near the shock tower. I imagine this has been taped over find the D+ connector there and touch that connector with the point end of the test lamp to the plug connector there will be two wires there, one blue, the other blue/red.
The test light should work as a substitute for the dash indicator. This should make the voltage at the battery jump up to around 13 volts.

Al

[rb6667]

Thank You very much Al.  I'll try that and report back.  Many thanks 

Happy New Year.