My stupid Jeep question of the day

Sounds like you have a burned fuse link wire to me or a dead (polished up) fan belt.

Follow the main power wire from the alternator to the solenoid. There will be a fuse link wire about 8" long with a rubber insulation and a big rubber tube crimp connector on the harness side just at the solenoid. Look for burns or pull on it to see if the wire inside the rubber case is cooked.

A multimeter can also check for continuity between the solenoid and alternator.

Mike

travis wrote:

On Wed, 05 Nov 2003 17:40:28 -0500, Mike Romain shared the following:

The fan belt seems nice and uh...grippy. I like the sound of your suggestion. I'll give it a look. I just found my multi-meter so that should help. I only have 2 wires hooked up to my alternator... I've changed out only probably 2 alternators before this one over the years but I could have sworn there was a third wire on them. I'll trace the main red wire like you describe and *hope* to find it's fried. Thank you for the suggestion.

-- Travis

GM ones have a 3rd 'excite' wire to turn on the alternator.

It is a thin (usually brown) solid core wire that tags the coil power wire on the 12 volt side of the coil's ballast resistor or ballast wire in the CJ's. On the CJ's it tags the harness right to the passenger side of the brake booster.

When I turn my current alternator pulley, did it today, the crank turns too.

I have a really swingy alternator volt gauge right now and have a voltage drop from the battery center post to the alternator red wire. It also drops at the solenoid bolt and on the red wire's O ring and the red wire where it goes into the cable clamp on the battery. If I put the meter on the positive cable clamp, I have no drop, so the connection between the clamp and the main wire is toast which kills my battery pretty fast.

I just keep on charging up my battery because I am not in good enough physical shape right now to take the sucker apart and clean it. I am in recovery from a nasty car accident I was a passenger in. T-bone hit on the passenger door where I was sitting. Physiotherapy says I am lucky I have a 19.5" neck or it likely would have been broken and I have had a stroke from my head hitting the door post. I am not allowed to turn wrenches, or better said I am not allowed to bend in the right ways to turn wrenches....

If you use the meter on 20 volts, check the two battery posts with the engine running, then move the meter probes to the clamps one at a time and see if the volts drop.

Then have the red meter probe on the positive and go to the alternator case, the volts must be 'exactly' the same.

Then hold the black meter probe on the neg post and go to the red bolt on the alternator, then back to the solenoid bolt, then to the solenoid wire cable loop, then to the red wire clamp on the battery.

If the voltage drops even 0.01 volts, the connection is bad.

Mike

travis wrote:

I think this is your problem. Per my wiring diagram for '76, the green wire runs from the field terminal to terminal 44 on the regulator. If this isn't hooked up the alternator gets no "exciter" current and basically doesn't generate any juice. The regulator should have a yellow wire at terminal 40, which is spliced in the harness to the big red "bat+" wire off the alternator, and a black wire at terminal 16 also spliced in the harness to the red w/trace wire off the ign switch.

Fix the green wire and I'll bet the thing works.

He tried that.... maybe he didn't wait long enough?

-- JimG

Hi Mike, Really sorry to hear of your accident. Get well friend.

Coincidentally, I've got the same thing happening with the sentra. I know it's sort of off topic, but along the same line. It left my wife walkin' the other day. When I got to where the car was it was dead dead. I pulled the battery and put it on my charger until topped off. Went to the car started it, got it home. Checked my connections with and without engine running. I know this is not the best thing to do, but I disconnected the negative battery terminal, with the engine on, and it died. Mind you, this is the second alternator to crap in this vehicle. This one only lasted 8 months! Strange? The odd thing this time was that red idiot light on the dash was not lit up like it was when the original one died. Could this be because the battery was nearly full? Only had to drive it about a mile and half. My wife couldn't remember or didn't notice a red light on. Fortunately, this has a lifetime warrantee and Auto Zone handed over a replacement without question. Pretty impressed. They had all my warrantee info in their computer system. Didn't need the receipt even though I had it with me.

On Wed, 05 Nov 2003 17:40:28 -0500, Mike Romain shared the following:

Zero ohms between solenoid and alternator. Line looks good. :-/

-- Travis

Travis,

If this is a '76 304, and it hasn't been rewired to another spec, yes, it should only have two wires, a large red wire running through the fusible link to the "+" battery terminal, and the green wire running to the field terminal. The alternator should ground through its housing to the mounting bracket on the engine. (Just a thought, you might try running a jumper wire from the alt housing to the negative terminal and see if it starts to charge. If so there's a grounding problem at the alt.)

The regulator should have a black (ignition switched positive) wire at its terminal, a yellow (battery positive) wire at a terminal "40", and your green field wire at terminal 44. Check to see if there's 12v. at the black wire with the key on, and if there's 12v at the yellow wire at all times. Also, even though you repaired it, make sure there's continuity in the green wire to the alt. field.

So, if all that passes muster and there's no voltage output from the alt then it sounds like either the new alt is toast, or more likely, the regulator is shot. Before I'd spend any more money I'd get the new alt tested just to be sure it's ok.

Hope this helps!