charging system problems
Thread Starter
Drifting
Joined: Oct 2003
Posts: 1,486
Likes: 10
From: Big Pine Key FL
charging system problems
Ok maybe I'm just to close to the problem...
Symptom: New reman Delco 12SI 94A alternator works for 279 miles then wavers the volt meter needle and dies. No output. Field and Sense wire check out ok, Bat wire checks out ok to horn relay. I was not happy with the mount so I switched to a Brand Spanking new denso 86A race shop alternator and went from 1.2x crank speed to 1.5x crank speed and changed form a 10mm wide belt to a 20mm wide belt to get more amps at Idle and still be in the RPM range of the alternator. Wired up the Denso and still no output it's the same deal a sense wire from in the harness an ignition wire to energize the field and an output wire. While i was at it I replaced the horn relay and reterminated the wires as they were corroded after 30 odd years. Sense wire checks out, Ignition/field wire checks out but no output.
I'm beginning to think I have a DOA New Alternator. I would expect to see 13.5 to 14.5 volts off the bat post on tha alternator or at the horn relay I get 11.9 CCV and 12.2 OCV which tells me I am getting nothing from the alternator.
Am I missing anything ?
I'm pullling the Voltmeter connection from the positve terminal pigtail on the battery that supplies my ECM and was getting 12.9 volts at 800 rpm and 13.8 at 1200 rpm before the problem.
The horn works ok
I'm gonna check for AC ripple on the output to see if any of the diodes are shot, and check that the field is not open or shorted and I'm gonna order up a new delco and a new denso alternator.
Symptom: New reman Delco 12SI 94A alternator works for 279 miles then wavers the volt meter needle and dies. No output. Field and Sense wire check out ok, Bat wire checks out ok to horn relay. I was not happy with the mount so I switched to a Brand Spanking new denso 86A race shop alternator and went from 1.2x crank speed to 1.5x crank speed and changed form a 10mm wide belt to a 20mm wide belt to get more amps at Idle and still be in the RPM range of the alternator. Wired up the Denso and still no output it's the same deal a sense wire from in the harness an ignition wire to energize the field and an output wire. While i was at it I replaced the horn relay and reterminated the wires as they were corroded after 30 odd years. Sense wire checks out, Ignition/field wire checks out but no output.
I'm beginning to think I have a DOA New Alternator. I would expect to see 13.5 to 14.5 volts off the bat post on tha alternator or at the horn relay I get 11.9 CCV and 12.2 OCV which tells me I am getting nothing from the alternator.
Am I missing anything ?
I'm pullling the Voltmeter connection from the positve terminal pigtail on the battery that supplies my ECM and was getting 12.9 volts at 800 rpm and 13.8 at 1200 rpm before the problem.
The horn works ok
I'm gonna check for AC ripple on the output to see if any of the diodes are shot, and check that the field is not open or shorted and I'm gonna order up a new delco and a new denso alternator.
J/K
