legacycentral bbs

Well, the car is at the mechanic and I'm being told there's a problem with the wiring. I thought that the WRX harness should be able to plug into the FWD chassis harness. Either that's the problem or the fuel pump is bad. To my understanding, the WRX gas tank harness should plug in no? Or is Justin right, do I need the harness from an AWD Legacy?

I remember changing my wire harness from tank to under the seat. But i honestly cant remember why, makes sence to me that its a lil different, even tho i was told they are the same. I would think a wrx one would be fine but the connector under the seat mite be different. I had a 91 awd parts car that i used the harness from

I can see why you would have done that; the WRX gas tank has other sensors and plugs that are left with nowhere to go. I don't understand why my mechanic is having an issue. He should theoretically be able to plug the FWD chassis into the WRX harness fuel pump. If nothing else is connected, I should still have a functional gas tank with the exception of an inaccurate gas gauge as a result of the senders...

Well. Hope i dont confuse. But ive done many subaru mods. I installed a sti tank in my 92 tw. Fairly certian i didnt change the harness when i did this tank swap.. As per this tread
But i have also done a 2wd to awd swap. On that car i remember changing the tank and wire harness cuz the 2wd tank is very different.. I also needed to add part of the transmission wiring as this car stayed automatic.

Do you think I could use the FWD fuel tank harness on the WRX tank?

Or can I just splice the WRX gas tank harness to work with the FWD chassis plug? If so, does anyone know where I can find some diagrams?

If not, does anyone know which years fuel cords/tank harness would be compatible with the WRX tank? Should I be looking for a 90-94 Legacy or will some of the newer ones work?

EDIT: In case anyone is looking, I found the part number for the Fuel Cord harness for a 1994 AWD Legacy. I ordered one and hopefully expect the harness to plug into the WRX tank thereby allowing it to plug into my FWD chassis. The gentleman on the phone told me there were only 4 in existence in the nation! The part number is: 81802AC000

Its possible. If you have a junk yard near by i would grab one out of an awd 91-94. Should be pretty cheap. Maybe the wrx one is just pinned differently. I also would test your pump by it self.
Good luck. Let us all know what the problem is. Cuz now im very curious. Wish i could dig around in there for ya and figure it out

Hows it going cheif? Did u get her all fingered out???

No updates as of yet... I ordered the tank harness from 94 AWD Legacy and waiting on that. I suspect that is the only obstacle left at this point. It makes total sense too considering that the AWD tank has 2 senders and the FWD tank only has one. I'd only have a repinning left to do and then it seems as if everything should work (crossing fingers).

Legacy777 wrote:The wiring harness is exactly the same between the FWD & AWD chassis.

I apologize, I should clarify this post.....the electrical connector that plugs into the connector that goes inside the cabin is the same between the FWD & AWD, but yes the on-tank electrical harness will be different since there is only one fuel sender on the FWD tank.

Well, I'm crossing my fingers that this solves the problem. The goal is to put this harness on the WRX tank and then hook it up to the chassis. Given that according to Josh the FWD/AWD cabin harness is the same and the swap was plug and play for Justin (AWD tank to AWD chassis), I should be good to go. I understand I may or may not have a functional gas gauge but I can deal with that once it gets warmer. Send any good vibes you may have my way!



P.S: Josh, once the car is running, I'll send you those badges I've been meaning to get over to you.

I got my fingers crossed for ya brother

thenicky0 wrote:P.S: Josh, once the car is running, I'll send you those badges I've been meaning to get over to you.

Ok, no problem. Just let me know when you send them so I can keep an eye out in the mail.

justin the subie wrote:Well. Hope i dont confuse. But ive done many subaru mods. I installed a sti tank in my 92 tw. Fairly certian i didnt change the harness when i did this tank swap.. As per this tread
But i have also done a 2wd to awd swap. On that car i remember changing the tank and wire harness cuz the 2wd tank is very different.. I also needed to add part of the transmission wiring as this car stayed automatic.

The car's still at the shop and dragging

I'm curious though Justin, did you use the WRX/STI fuel pump when you replaced the tank or did you just swap out your old AWD on the new tank? I'm reading about WRX fuel pumps now (which is what I have on the tank) and reading about the controllers they have to lower voltage. Hope that's not an issue on my car...

This is where I'm at right now:

My gas gauge is not working. I have the diagrams for the 2002 WRX and the 1992 Legacy. I have the WRX tank with the WRX fuel pump and sender using the Legacy AWD harness on it. I'm going dizzy looking at these diagrams. I will paypal you $20 (or anyone else for that matter) that can make sense of this diagram and instruct me as to which wires have to be moved where lol

So here's the skinny. The low fuel light on our Legacies uses a separate sensor, which is why the 92 diagram shows three wires going to the "fuel gauge unit". Pin 2 of the R75 connector is for the low fuel light sensor. Pin 3 of the R75 connector is related to the actual fuel gauge and comes from the sub unit, and pin 5 of the R75 connector completes the circuit and goes to the dash.

On the WRX, connector R58 is the same as connector R75 on the Legacy. On connector R58, pin 3 serves the same function as pin 3 on the R75 connector. However, pin 2 on the R58 connector is different than pin 2 on the R75 connector. Pin 2 on the R58 connector completes the circuit and goes back to the dash, while pin 2 on the R75 connector is for the low fuel warning light.

To make your fuel gauge work what I recommend doing is swapping wires around on the connector under the rear seat, and not the connector that plugs into the fuel tank. Swap pins 4 and 5 of the R9 connector. Pin 4 the wire color is red with a white stripe, and pin 5 is a black wire. That should work. You won't have a low fuel warning light.

Legacy777 wrote:So here's the skinny. The low fuel light on our Legacies uses a separate sensor, which is why the 92 diagram shows three wires going to the "fuel gauge unit". Pin 2 of the R75 connector is for the low fuel light sensor. Pin 3 of the R75 connector is related to the actual fuel gauge and comes from the sub unit, and pin 5 of the R75 connector completes the circuit and goes to the dash.

On the WRX, connector R58 is the same as connector R75 on the Legacy. On connector R58, pin 3 serves the same function as pin 3 on the R75 connector. However, pin 2 on the R58 connector is different than pin 2 on the R75 connector. Pin 2 on the R58 connector completes the circuit and goes back to the dash, while pin 2 on the R75 connector is for the low fuel warning light.

To make your fuel gauge work what I recommend doing is swapping wires around on the connector under the rear seat, and not the connector that plugs into the fuel tank. Swap pins 4 and 5 of the R9 connector. Pin 4 the wire color is red with a white stripe, and pin 5 is a black wire. That should work. You won't have a low fuel warning light.

Josh you're the man. I was actually looking at my hand drawn diagrams and was comparing the R75 connector with the WRX R58 connectors and noticed a lot of similarities except for Pin 2. I had that Eureka moment but you illuminated what my foggy brain could not come up with lol I'm gonna try this tomorrow and see how it goes. I'm excited to see how it goes I'll make sure to keep you guys updated. And since I'm sending you the badge this week, I'll make sure to include a more personalized gift in there for you for all of your help.

Cheers!

P.S: A legitimate thanks for explaining it to me like I was 5 lol Wiring is the death of me.

You're very welcome! Let us know if it works once you've had time to try it out.

Legacy777 wrote:So here's the skinny. The low fuel light on our Legacies uses a separate sensor, which is why the 92 diagram shows three wires going to the "fuel gauge unit". Pin 2 of the R75 connector is for the low fuel light sensor. Pin 3 of the R75 connector is related to the actual fuel gauge and comes from the sub unit, and pin 5 of the R75 connector completes the circuit and goes to the dash.

On the WRX, connector R58 is the same as connector R75 on the Legacy. On connector R58, pin 3 serves the same function as pin 3 on the R75 connector. However, pin 2 on the R58 connector is different than pin 2 on the R75 connector. Pin 2 on the R58 connector completes the circuit and goes back to the dash, while pin 2 on the R75 connector is for the low fuel warning light.

To make your fuel gauge work what I recommend doing is swapping wires around on the connector under the rear seat, and not the connector that plugs into the fuel tank. Swap pins 4 and 5 of the R9 connector. Pin 4 the wire color is red with a white stripe, and pin 5 is a black wire. That should work. You won't have a low fuel warning light.

So I don't have a clue in hell what I just did except that I switched the wires between 4 and 5 on the female side of the connector under the rear seat and I now have a fuel gauge lol

I will update you guys as I drive the car more and more but as of now (crossing my fingers) I have a full, functioning fuel gauge Thank you guys for all of your help.

You're welcome

Glad to hear it's working.

For anyone else in the future planning this, i found this thread.

http://www.rs25.com/forums/f105/t196374 ... -swap.html

Seems like there's some good information in there.

CJ,

Thanks for posting, that is some good info.

Yeah, it will probably be my solution to the question you asked 8n my build journal.

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If I was going to do anything major, I'd consider doing a swap so I could relocate the charcoal canister to the rear of the car like on the newer cars, and maybe in the fuel pump...and would have the ability to run a fuel temp sensor.