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Guest Message by DevFuse
 

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1999 Legacy L No FWD light code 79


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10 replies to this topic

#1 waslydog

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Posted 26 July 2013 - 10:36 PM

Picked up my brothers 99 Legacy L today. AT light flashing and am experiencing torque bind. Did the secret hand shake came up 79. Put a 30 amp fuse in fwd fuse holder,fwd light didn't come on and still getting torque bind. 

Don't know if it's relavent but he says the light started flasing when he accidently overfilled trans.

Any thoughts would be greatly appreciated



#2 waslydog

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Posted 27 July 2013 - 11:14 AM

I haxe noticed that some don't think that a code 79 exists. I got this code from the following link; http://www.subaruout...codes-dtcs.html



#3 waslydog

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Posted 28 July 2013 - 02:50 PM

Ok, so I tried a 20 amp fuse, fwd light came on no torque bind. Duty C solenoid??? Anyone?



#4 WoodsWagon

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Posted 28 July 2013 - 07:17 PM

You probably just didn't have a good connection with the first fuse. Since the fuse holder sits empty all the time it can get a layer of corrosion on the connectors.

 

If the torque bind goes away with the fuse in, then the duty C is working. It also means you have a good chance of curing it by changing the fluid a few times in a row with short drives in between.

 

How overfilled? Are you checking the right dipsticks?  There's two on the transmission, one is straight and stick-like it's for the front diff, the other  is flexible and blade like, it's for the trans.



#5 waslydog

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Posted 28 July 2013 - 08:57 PM

Thanks for the info I'll find the other dipstick and check it also. Will also try the drain and fill.



#6 johnceggleston

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Posted 29 July 2013 - 12:55 PM

as mentioned, if the FWD light comes on then the duty c is working.

 

but if the duty c is working and you still have the flashing AT Temp light, and a code 79, then there is conflicting info.

 

the AT Temp light indicates an electrical fault in the trans the last time you drove it.

the code indicates it is the duty c.

so does the binding.

 

change the fluid and see, it can't hurt.

 

there have been case where the TCU was bad and causing the binding.



#7 chaz345

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Posted 29 July 2013 - 04:17 PM

as mentioned, if the FWD light comes on then the duty c is working.

Not necessarily. The FWD light will come on just with the fuse present in the holder. But the torque binding going away with the fuse installed does suggest that the duty c itself is OK.   I had a 91 Legacy that had an intermittant torque bind problem and an intermittant flashing "power" light. Sometimes torque bind and flashing light even with fuse installed. Known good Duty C, known good TCU. Turns out that it was a bad wire from the TCU to the duty C.



#8 johnceggleston

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Posted 30 July 2013 - 06:54 AM

i have never had the FWD light on when the duty c was bad.

whenever the duty c has been bad, i have not had a FWD light.

 

but i have not explored all possibilities so who knows?


Edited by johnceggleston, 30 July 2013 - 06:55 AM.


#9 chaz345

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Posted 30 July 2013 - 10:08 AM

i have never had the FWD light on when the duty c was bad.

whenever the duty c has been bad, i have not had a FWD light.

 

but i have not explored all possibilities so who knows?

Could be a difference in the older versus newer generation. I've only had a 91 and a 93 where it's not the AT Temp light that flashes but the power light so it's entirely possible that other parts of how it works electrically were changed too.    Having the FWD light not come on when the duty c is bad would be an excellent diagnostic if they did that intentionally though.  I'm currently running without my rear driveshaft installed because one of the u joints was going bad and I was having torque bind. With the FWD fuse installed, I have consistent FWD light but also intermittantly have the flashign power light on startup so it would seem thsat the TCU doesn't like something.



#10 waslydog

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Posted 30 July 2013 - 10:18 AM

Single flush and fill did the trick :) No torque bind, no AT temp light. Thanks to all for your input. Sorry for tthe impatiance.

Now on to replacing front drive shafts.


Edited by waslydog, 30 July 2013 - 10:20 AM.


#11 johnceggleston

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Posted 30 July 2013 - 06:42 PM

good job.

 

keep at it.






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