I have an electrical mystery that I hope much wiser minds than mine can help solve.
Recently purchased a 2000 Land Cruiser, and the battery drains after about 36 hours of sitting.
Investigation conducted thus far:
- Confirmed 14.6 V at battery when alternator is charging.
- Tracked down parasitic current as being associated with the Alt-S fuse. When in place, my multimeter shows a parasitic current of about 450 mA. When I pull the Alt-S fuse, the parasitic current drops to 8-10 mA.
- pulled the alternator and took it to the parts store - they tested the alternator and every parameter was well within normal parameters (does this parts-store test look for anything like a short, or is it just looking for sufficient voltage and amperage)?
- had the battery tested and it also passed with flying colors (less than 11 months old)
- while the alternator was out, I tested the wiring to the alternator and confirmed <1 ohm resistance between the positive battery terminal and the S pin of the connector.
- plugged the alternator back in but did not install the alternator back on the engine (i.e., the alternator was not grounded) - parasitic current remained at no more than 10 mA
- installed the alternator back on the engine, parasitic current is now back at about 450 mA.
Possibly relevant facts:
- alternator does not appear to be denso/OEM
- previous owner installed a new alternator connector pigtail and , and did the ol' twist-and-tape method of connecting the connector wires to the vehicle wiring (that will be corrected shortly) - however, the conductivity is unimpacted and there is no measurable resistance between the connector pin and battery, so this shoddy worksmanship doesn't appear to be the source of the parasitic draw (in the presence of the parasitic current, I felt the junction between the connector wire and the vehicle wiring and there was no notable heat through the mound of electrical tape)
Hypothesis: since the parasitic current reappears once the alternator is grounded to the engine block, there is a short between the alternator casing and the Alt-S signal wire, and the easiest solution is to buy a new alternator
Any other possible causes or things to investigate before I drop $$$ on an OEM alternator?
TIA
Recently purchased a 2000 Land Cruiser, and the battery drains after about 36 hours of sitting.
Investigation conducted thus far:
- Confirmed 14.6 V at battery when alternator is charging.
- Tracked down parasitic current as being associated with the Alt-S fuse. When in place, my multimeter shows a parasitic current of about 450 mA. When I pull the Alt-S fuse, the parasitic current drops to 8-10 mA.
- pulled the alternator and took it to the parts store - they tested the alternator and every parameter was well within normal parameters (does this parts-store test look for anything like a short, or is it just looking for sufficient voltage and amperage)?
- had the battery tested and it also passed with flying colors (less than 11 months old)
- while the alternator was out, I tested the wiring to the alternator and confirmed <1 ohm resistance between the positive battery terminal and the S pin of the connector.
- plugged the alternator back in but did not install the alternator back on the engine (i.e., the alternator was not grounded) - parasitic current remained at no more than 10 mA
- installed the alternator back on the engine, parasitic current is now back at about 450 mA.
Possibly relevant facts:
- alternator does not appear to be denso/OEM
- previous owner installed a new alternator connector pigtail and , and did the ol' twist-and-tape method of connecting the connector wires to the vehicle wiring (that will be corrected shortly) - however, the conductivity is unimpacted and there is no measurable resistance between the connector pin and battery, so this shoddy worksmanship doesn't appear to be the source of the parasitic draw (in the presence of the parasitic current, I felt the junction between the connector wire and the vehicle wiring and there was no notable heat through the mound of electrical tape)
Hypothesis: since the parasitic current reappears once the alternator is grounded to the engine block, there is a short between the alternator casing and the Alt-S signal wire, and the easiest solution is to buy a new alternator
Any other possible causes or things to investigate before I drop $$$ on an OEM alternator?
TIA
