Charging Problem Revisited, Everything Swapped Options

[Allan]

Okay, been having a charging problem for awhile now. Started replacing and checking over everything. So far I've replaced the voltage regulator, relay board and now finally replaced the alternator and harness. Guess what??? No freaking charge to the battery. (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif)

Any ideas????????????????????????

[ArtechnikA]

didn't see the generator bulb in the dash instrument listed in your litany.

it MUST be there and it MUST be exactly the correct bulb. it is part of the charging circuit. really.

[Allan]

I've never replaced the bulb. It's the one that has always been in the car. (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

[lapuwali]

If the G light doesn't come on when you switch on the key (engine off), then you need to replace it. If this bulb is burnt out, you don't get any charging.

[skline]

The light stays lit the entire time the car is running. So it is not the bulb. Any other suggestions?

[lapuwali]

Could be the "new" VR is also bad. This apparently happens a lot with Bosch VRs.

Here's how this all works:

The alternator generates AC current by spinning a coil of wires inside another coil of wires. The stationary coils are electromagnets initially energized by the battery. The current for this runs through the ignition switch and the G bulb, which is why the light is on with the engine off/switch on. Once the spinning coils get going fast enough, they're generating their own current into the battery, which is throttled by the voltage regulator. The voltage between the two terminals on the G bulb will then go to zero, so no current flow, so the bulb goes out. The alternator electromagnets are now "self-energizing".

If the bulb comes on while the engine is running, there's a voltage imbalance across the bulb, so the voltage is high or low on one side (battery or alternator) relative to the other. The causes for this are:

alternator is generating less than 12.5v (the "rest voltage" of a good battery)
the VR is holding the generated voltage below 12.5v
the battery is horked (esp. if it's internally shorted)
there's a short to ground between the G bulb and the alternator (no fuse here, and the bulb should be bright)

The battery should show 12.5v across the terminals with everything disconnected. If not, try slow charging it for awhile. If that doesn't get it back up there, replace the battery.

Test the "new" alternator and VR. New Bosch VRs seem to be bad in the box distressingly often these days. Rouser knows the part number of a solid-state Borg-Warner VR that's much more reliable. Do a search here for it (recent discussion).

[Allan]

Here's the deal, everything has been tested and found to be good. Is it possible that the problem lies somewhere in the main harness or behind the instrument cluster?

[lapuwali]

Yes, if the G lamp wire is shorted to ground between the lamp and the alternator, you'll get a bright lamp but no current to the field coils on the alternator, so no charging. This could also cause a nice little fire, and will discharge a battery pretty quickly. It would also eventually fry your ignition switch.

Try removing the bulb and hook a meter to the alternator side wire and ground and see if you have continuity.

If this doesn't work, post all the steps you took to check things out. Sometimes just going over things again reminds you of something you forgot.

[GWN7]

Hey I was right about the bulb.....sorry nothing else to add.... (IMG:http://www.914world.com/bbs2/html/emoticons/sad.gif)

[Allan]

Well, for some reason my charging system is functional. I had Scott drive it today to listen to the knocking noise I was hearing (not a rod thankfully). Light is on as usual and we return to his house. I get in it to drive it up on the trailer and guess what??? Light is out. I pulled the vr to see if the idle changed and sure enough it goes up. Put it back in and idle goes down. Hhmm, we have a charging system. I trailer it home, start it up (no light) and pull it into the driveway. Left it running and got my volt meter. 14 volts at the battery. (IMG:http://www.914world.com/bbs2/html/emoticons/clap.gif) Took it out and drove around for awhile and everything is working.

I HATE problems that go away by themselves... They usually come back at the most inconvenient time....

[redshift]

-checks watch-

-drops hand-

(IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)


M

[Allan]

QUOTE (redshift @ Jun 12 2005, 06:55 PM)

-checks watch- -drops hand- (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif) M

Mles, wake up....


Anybody else have an answer?????????

I don't want to deal with this again....

Main harness? Instrument issues???

C'mon you electrical gurus........................

[GWN7]

Check the part of the car that you kicked in frustration for something loose. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[JoeSharp]

Allan: The only reason I can do an alt. exchange in 45 minutes is that I did it 5 times in a week for varerious reasons. One was the conectors that were not making a conection inside the plug. I would push the plug all the in and the conectors in the plug would not contact. Use something to make sure that the conectors inside the plug are pushed in all the way.
:PERMAGRIN: Joe

[Aaron Cox]

QUOTE (Joe Sharp @ Jun 13 2005, 09:35 PM)

Allan: The only reason I can do an alt. exchange in 45 minutes is that I did it 5 times in a week for varerious reasons. One was the conectors that were not making a conection inside the plug. I would push the plug all the in and the conectors in the plug would not contact. Use something to make sure that the conectors inside the plug are pushed in all the way. :PERMAGRIN: Joe

Joe,

allan and i beat you. we did it in like 20-30 minutes at sklines casa....

gettin old there pal, beat by the young blood LOL


laterz fella's

AA

[markb]

Are you really sure the relay board is good? I've had more than one work fine until it warmed up, then crap out on me.

[bd1308]

yeah those connections, when they get hot, will expand and make intermittent or no contact...the connections are actually riveted. I usually take them out and solider all of the connections with the good ol' 60/40 tin/lead soldier.....maybe thats why I am the way I am....too much lead.

[john rogers]

What are the resistance readings on the batt cables and connectors and the ground from the engine to the body? Also, when you install the new alt are you unhooking the batt NEG terminal? If not you are probebly cooking the diodes in the alt. Good luck

[Joe Bob]

I've had two recent alternator problems and it's ALL been the D+ line problem......

On my sixer motors, the alt is a three wire unit. Ya gots da big wire, the ground wire and da D+ one.

The D+ HAS to have a working bulb that goes ON when the ignition is turned on, then will eventually go dim when the alternator is charging......

In one case, I had to put a diode in line to get the engine to shut off when the ignition was turned off....this was due to excessive voltage from an MSD unit.....

WHAT "I" would do....is run a NEW D+ wire from the alternator with a WORKING bulb inline to switched circuit on the fuse box and test the circuit.

Fire up the engine and check voltage at the battery. 12.5v at rest, 13.0 ish at idle, 13.5-14.0 at 2500 rpms....

[retrotech]

I am having a charging problem also. My gen. light didn't come on. When I put a grouded test light on it the light came on. So I assume I have a ground problem? Where to I look first? I have replaced the battery & VR, now what?
Help!