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My new to me 968 appears to have a parasitic drain on the battery. I noticed that the underhood light was unplugged, and put that back together. I haven't had time to test yet, but I was wondering if where the wiring harness exits the hood and bends down in the engine compartment could have some frayed/shorted wires inside the bundle? Other quick places to test would be appreciated.
Am not as familiar with 968s as with 944-914-911-951 cars,
BUT with that said:
One of the more common trouble spots for parasitic current loss is with the alarm systems in those above mentioned cars. Also an alternator which is old and has begun to show charging issues on the gauge may also be a culprit
I would also check first the battery condition and do a load test on it. As well as make sure all the terminal connections are clean and in good form. Often times the cables will corrode inside their jackets and upon opening up an old cable, one may see corrosion all up and down the inside of the copper core.
So check these items first as well as where the underhood light wire passes thru ( and I have never seen one ever wear thru here other than the possibility of a mouse chewing on it ).
Not sure about the positioning of your wires and the coil wire around your headlamp retraction arms on a 968, but the coil wire often gets nicked by being out of it's holding clamp, by the arms on a 944/951 and will cause intermittent ignition issues. Make sure all your bundling is intact there as well and BEST wishes with finding your draw down source.
Am not as familiar with 968s as with 944-914-911-951 cars,
BUT with that said:
One of the more common trouble spots for parasitic current loss is with the alarm systems in those above mentioned cars. Also an alternator which is old and has begun to show charging issues on the gauge may also be a culprit
I would also check first the battery condition and do a load test on it. As well as make sure all the terminal connections are clean and in good form. Often times the cables will corrode inside their jackets and upon opening up an old cable, one may see corrosion all up and down the inside of the copper core.
So check these items first as well as where the underhood light wire passes thru ( and I have never seen one ever wear thru here other than the possibility of a mouse chewing on it ).
Not sure about the positioning of your wires and the coil wire around your headlamp retraction arms on a 968, but the coil wire often gets nicked by being out of it's holding clamp, by the arms on a 944/951 and will cause intermittent ignition issues. Make sure all your bundling is intact there as well and BEST wishes with finding your draw down source.
Thanks! Not the best time of year to be doing this type of testing since it resides outside and the 944 is in the garage. I do know that the battery is only slightly over 1 year old, terminal connections are clean and tight. Recharged the battery, but it is discharged again. If the under hood bundle checks out ok, next step would be alarm system. The lighted door lock ***** don't light up, so there may also be issues there.
I've been an owner of three NA 924s' and one of them had a 'significant' parasitic drain. It turned out that the fresh-air intake motor never turned off but, rather, remained turning at a slow speed that was undetectable from within. I happened to be working in that area when I realized that it was on. Strange. I decided to 'fix' this by installing an old 356/911 kill switch. Very cool but there's any hope for a Concourse winner.
I was suffering from a dead battery every morning on a '87 924 and after tossing a battery at it I was perplexed by the drain until one night,hours after I had parked it I went to the car to disconnect the battery cable for the morning commute and the cooling fans were on. Quick fix under $10 for a fan switch in the radiator. If the 968 has a similar setup I wouldn't rule that out.
on my 86 944t the Hvac fan is constantly on. its on the 0 position and the fan still runs very slow even with the ignition key out. monitored it over night, took the battery reading at 12.44 at 2100hrs and took it again at 0700 the following day and it was 11.99. so now every night when i park it i take the fuse out and just plug it in before i drive. still cannot figure why my fan stays on. any help would be greatly appreciated.
I was suffering from a dead battery every morning on a '87 924 and after tossing a battery at it I was perplexed by the drain until one night,hours after I had parked it I went to the car to disconnect the battery cable for the morning commute and the cooling fans were on. Quick fix under $10 for a fan switch in the radiator. If the 968 has a similar setup I wouldn't rule that out.
Fans are definitely not running. Will hopefully do a drain test tonight or tomorrow. I'm placing my bets on either the under hood light harness or the alarm/central locking system as first culprits to research.
My new to me 968 appears to have a parasitic drain on the battery. I noticed that the underhood light was unplugged, and put that back together. I haven't had time to test yet, but I was wondering if where the wiring harness exits the hood and bends down in the engine compartment could have some frayed/shorted wires inside the bundle? Other quick places to test would be appreciated.
I previously had a frustrating parasitic drain in my 928 and using a process of elimination testing approach was able to identify the culprit (water entering interior cabin light at hatch- intermittent and weather related!).
If you have access to an inexpensive digital multi-meter with an amps setting you could narrow down your faulty circuit search quickly; forgive me if I'm preaching to the choir here but you might try:
test for parasitic drain without key engaged in ignition
disconnect the negative cable terminal from negative battery post
set multi-meter to highest amp setting
connect leads of multimeter in series between negative battery post and the negative cable terminal
you should be now reading the current usage ('at rest'), if only dealing with a parasitic drain should only be a couple of hundred MA.
Note the reading
One by one, remove and replace individual fuses (lights, alarm, fan, stereo, etc.etc) and note the resultant change (reduction) in current flow
The culprit should exhibit the most disproportional change in current flow when removed.
That might point you to the system affected, to narrow down your area of attention.
I previously had a frustrating parasitic drain in my 928 and using a process of elimination testing approach was able to identify the culprit (water entering interior cabin light at hatch- intermittent and weather related!).
If you have access to an inexpensive digital multi-meter with an amps setting you could narrow down your faulty circuit search quickly; forgive me if I'm preaching to the choir here but you might try:
test for parasitic drain without key engaged in ignition
disconnect the negative cable terminal from negative battery post
set multi-meter to highest amp setting
connect leads of multimeter in series between negative battery post and the negative cable terminal
you should be now reading the current usage ('at rest'), if only dealing with a parasitic drain should only be a couple of hundred MA.
Note the reading
One by one, remove and replace individual fuses (lights, alarm, fan, stereo, etc.etc) and note the resultant change (reduction) in current flow
The culprit should exhibit the most disproportional change in current flow when removed.
That might point you to the system affected, to narrow down your area of attention.
Good luck in your troubleshooting
Yes, that was the idea on how I would approach testing. I want to start with the underhood light circuit just because I noticed the light was unplugged and thought that was odd, and potentially a clue as to how PO was avoiding issue instead of tracing to source and actually repairing. Testing process depends on a charged battery, so that was first step last night to get the battery out and get it charged up. Hope to get car in garage tonight and do first tests, then move it back out either way (identified or not) since I won't have time to actually effect a repair if the issue is identified.
When you shut off a 944, the power windows should still work. When you open the door, the switch in the door jamb turns on the dome light but it also deactivates the power windows. If you can open your door, ignition off, and the power windows work then a buggered door switch could be your cause. Non-working dome lights share the same cause. Check the trigger switch just under the top door hinge. It's one screw to pop it out, clean and lube. My experience is with 86-89 944s, not sure about others.
When you shut off a 944, the power windows should still work. When you open the door, the switch in the door jamb turns on the dome light but it also deactivates the power windows. If you can open your door, ignition off, and the power windows work then a buggered door switch could be your cause. Non-working dome lights share the same cause. Check the trigger switch just under the top door hinge. It's one screw to pop it out, clean and lube. My experience is with 86-89 944s, not sure about others.
Found the circuit, now just have to locate the problem within the circuit. Pulled fuse for interior lights, under hood light, got the difference between the two attached pictures of the drain on the battery. .977A with fuse in, .061A with fuse out. I did notice that the dome light was always on even if in "on with doors open position". This leads me to believe the cause is somewhere in that chain. Is most likely place to look a short at door switch? With fuse in Fuse out draw
01-08-2019, 03:04 PM
Cause for parasitic drain?
