91 Subaru XT6 Grounding out

[ZxExD]

After spending $1,000's last year trying to get my XT6 running again, we are just about there. After putting a new engine in, it still is doing the same thing it was doing before. Car won't Idle, and I think we have it narrowed down to Mass Air Flow Sensor, will find out this afternoon after spending another $170. Just bought a new alternator and installed it.

 

Had problems with headlights one night, dim, not popping up, and the battery drains over night. Unplugged most of the wiring harness, checked fuses, and now getting feedback to alternator, melting black wire with white stripe. Furthermore, if you disconnect the negative post on battery, clamp/ground test light to body and touch negative post, light comes on which means there is a short to the body or engine showing about 9 volts.

 

Any suggestions?

[john in KY]

Time to start pulling fuses one at a time to narrow down the faulty circuit. I have a couple of XT6 AFM. Can't remember now what it is called but on the left side of the throttle body that regulates the idle. IAS? Should have a few of these also.  Pretty sure there is a diode somewhere in the charging systems there to prevent the battery draining back into the alternator. 

[ZxExD]

Subaru is running!!!!! Been sitting for almost 3 years, two engines, new exhaust, new alternator, injectors cleaned, new battery, and the thing that was wrong with it.....$170.00 Mass Air Flow Sensor!

 

Thanks for your input John, I still believe it is shorting out somewhere, but it is running properly. I was told it was the IAC, but it was the MAFS.

 

Still working on short.

[john in KY]

$175, wow. Would have sold one for $25. 

[ZxExD]

Have the wrong darn manual, covers the rest, but not XT6. Need to get one off Ebay I guess, anyways, been driving it, still has a couple problems to narrow down. We scratched our heads and tried everything to find that short to no avail. For now, I have disconnected the two wires (black and Green I think) that has been feeding back. Seems to be charging but not like it should be. Also been unhooking battery at night.

[idosubaru]

do you have anything custom or currently not working properly?  that would be a good place to look for drains.

 

it's pretty easy to diagnose and narrow down a drain - the final step may be cumbersome but this much is easy:

 

remove positive battery cable.  put a multimeter between positive battery terminal and battery terminal cable.

set it to milliamps. 

tell us how many milliamps it's drawing.  more than 50 and it's got a drain.

start disconnecting fuses until the drain drops to much lower - that will isolate your drain.

try disconntecting alternator too and see if draw decreases.

 

you don't want anything to turn on (lights, door opening, seat belts retracting, etc) while testing as it'll draw a bunch of current and blow the fuse in the multimeter

 

once you find the fuse then it gets a little trickier - look up everything run off that fuse and start unplugging each item one at a time until the drain drops. 

 

i just did this a couple weeks ago and it was the power seat belt controller on a friends XT6.

 

i may have a set of XT6 manuals available.

[ZxExD]

Put a meter from pos terminal to pos cable, not sure about the milliamps. Watched the needle and went through the fuses. Only fuse that made a difference was the, Horn/Clock/Hazard. It zeroed out when pulled. Pulled off alternator main, jumped a little but nothing significant, hooked up other to wires to alternator and it pegged the needle.

[ZxExD]

Ok, have digital meter, from strut mount (body) to Negative Post on battery we are getting 12.6 volts dc. From Positive post to positive cable its also 12.6 volt. Battery post to post is 12.6.