There is continuity in the entire charging circuit as diagrammed in the Haynes manual.
I performed the charging system check in the Haynes manual, which lead me down the "under voltage" check. All the tests passed except the last test, which I didn't do because the action to take after the last test is to replace the alternator regardless the result of the test.
There was 13 ohms between negative terminal and alternator housing, but I hooked a jumper wire from the negative battery terminal to the alternator housing and no effect.
None of the fuses are blown.
The positive battery terminal was heavily corroded. I replaced it, however it looks the the corrosion goes at least several inches into the wires.
Now here are more details of the problem:
- Turning on the lights/fan cause the battery indicator to drop.
- Coming to a stop causes the battery indicator to rise.
* pushing the clutch in while the vehicle is rolling does not cause the battery voltage to rise according to the battery indicator
- The voltage across the battery terminals drops when the engine is revved by about half a volt according to my DMM.
- There is 0.22 A being drawn while the vehicle is off (including all lights). That seems reasonable.
- The problem is still intermittent. It occasionally "clicks back in" and everything seems normal.
- When the problem is there, the oil and temperature gauges behave very unusually. The oil gauge will read slightly high and flutter occasionally, and the temperature gauge will read high - often it will climb high enough to turn on the warning light and then come down to normal in about 30 seconds.
- The vehicle will run with the positive lead disconnected from the battery (although its pretty rough and the battery indicator will read pretty low).
- The serpentine belt appears to be good (no cracks/splits/damaged ribbing).
"The positive battery terminal was heavily corroded. I replaced it, however it looks the the corrosion goes at least several inches into the wires."
If you just changed the ends and not the cable, this is a likely suspect. Still sounds to me like a bad connection and likely a ground (lack of) problem.
I sort of agree in that I would have more of a warm fuzzy feeling if I replaced the entire cable (actually there are two - battery<->alternator and battery<->starter relay).
However, like I said there is continuity... 0 ohms between positive lead and alternator output stud.
As for the ground, I even tried hooking jumper wire from negative battery terminal to alternator housing.
So the alternator is definitely in direct electrical contact with the battery. Maybe I really did just get two bad replacement alternators...
Otherwise there is some sort of short that is loading the system BUT
1) wouldn't this blow a fuse or circuit breaker or fused link?
2) how the hell would I ever find some obscure short somewhere in the electrical system????????
Have you connected a jumper from the neg. term. of the battery to the body and fire
wall ? What is your stator voltage ? Did you jump the regulator at the back of the
alternator ? That should give you about 20 volts and full amperage so make sure nothing is
The engine/alternator assembly was poorly grounded. There was a test in the Haynes manual that should have revealed this but I guess I was sloppy about it.
Basically, there is 1 wire that grounds the engine to the frame and it was making bad contact. Without the wire there is ~15 ohms resistance which is significant because of the low voltage/high current.
I have no idea why I didn't see this the first time I hooked up jumper wire from negative terminal to alternator housing - maybe it was because it was a small gauge wire and heated up too much (resistance increases with temperature) or maybe I just made bad contact.
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