E28Don
Member
I've done some searching here, and think that I have a course of action in my troubleshooting, but am looking for confirmation before I get too heavy into disassembly.
02 Jetta TDI, 200k miles, pretty much out of the blue, doesn't start after sitting overnight. Jumpstarts fine, starts again fine after running, but if it sits for a few hours while at work, needs jumped again. Took her to Advance Auto for electrical system diagnosis, report comes back: battery fine, charging system fine, but there's a 3.5A drain somewhere.
Using my trusty ammeter, I find the drain in the fusible link box on top of the battery. It's the heavy black wire, closest to the centerline of the car, and does show a 3.5A current with the battery hooked up (ammeter placed in-line between disconnected wire and fusible link terminal). With everything disconnected, that same wire shows 660 ohms to ground, fwiw. I believe that this wire goes to the alternator, and from reading here, this stray current could be due to a bad alternator diode, or frayed insulation on the wire. I'm inclined to think the diode is more likely, as a simple grounding of the wire would show a lot less resistance.
Other factors?: Radio has had a lot of static, esp. on AM; tried grounding radio chassis, to no effect, and removed extra ground strap. Glow plugs replaced several weeks ago. Battery is only six months old. Voltage across battery with car idling, 14.25V.
Proposed Course of Action: Trace cable from fusible link box to alternator. If nothing found there, assume it's the alternator and replace.
Am I on the right track?
Thanks in advance for your input.
Don
02 Jetta TDI, 200k miles, pretty much out of the blue, doesn't start after sitting overnight. Jumpstarts fine, starts again fine after running, but if it sits for a few hours while at work, needs jumped again. Took her to Advance Auto for electrical system diagnosis, report comes back: battery fine, charging system fine, but there's a 3.5A drain somewhere.
Using my trusty ammeter, I find the drain in the fusible link box on top of the battery. It's the heavy black wire, closest to the centerline of the car, and does show a 3.5A current with the battery hooked up (ammeter placed in-line between disconnected wire and fusible link terminal). With everything disconnected, that same wire shows 660 ohms to ground, fwiw. I believe that this wire goes to the alternator, and from reading here, this stray current could be due to a bad alternator diode, or frayed insulation on the wire. I'm inclined to think the diode is more likely, as a simple grounding of the wire would show a lot less resistance.
Other factors?: Radio has had a lot of static, esp. on AM; tried grounding radio chassis, to no effect, and removed extra ground strap. Glow plugs replaced several weeks ago. Battery is only six months old. Voltage across battery with car idling, 14.25V.
Proposed Course of Action: Trace cable from fusible link box to alternator. If nothing found there, assume it's the alternator and replace.
Am I on the right track?
Thanks in advance for your input.
Don