Will do. I'll try that today. If there is not power, where should I search? Possible bad relay? Or a fuse? I checked the fuse on the battery and it is good. Is there a fuse somewhere else that may be blown?

 

According to the tech that was working with me to solve the problem. He mentioned something about a relay on the firewall that usually doesn't create the issues but has done it a few times before. It's a rare case that the inline fuse or relay may have caused your pump issues however, not impossible. My apologies for not being able to provide a more accurate response to your problem, it was a very vague mentioning by the tech that it could be a possibility for pump failure pertaining to my situation.

 

Don't appologise, any help is wonderful. I am going to try replacing the relay if the pump is not recieving power.

 

Bad news on my end... my ACD pump died, again.

As a reminder, mine had stopped working the day after a track day. Upon taking the pump apart, we found that it looked perfectly clean, reassembled it, and all of a sudden it worked again when we retried it.

Well, it's dead again. It happened yesterday on my way home after a track day, so the failures seem to have something to do with hard driving.

I guess I'll take it apart again and see if it fixes itself again.

 

ACDC

Fixed, that'll be $20

 

What?

 

Mine is in and out as well. 3 lights are mostly on in the afternoon when its hotter, and after/during tuning sessions. They hardly ever come on in the morning. DTC is Electric pump circuit. Figured they could be a little more specific than that... Im definitely interested in any ideas for refreshing this thing in the garage. Otherwise the ACD case is coming out and a non-ACD case put in.

What do you guys think is causing it to start working for a while after taking it apart? Im wondering if its losing pressure internally and putting it back together sort of fixes the leak for a little while.

 

The seals within the pump itself seem to be failing or have failed. OR the pressure sensor switch is failing. I've done the math and it seems less costly to repair/replace the ACD pump before deleting the system completely unless of course you have a non-ACD T-Case on hand.

 

Chiming in. Pretty certain my pump is dying - I start the car and get a "whirriririririririrr", a metallic, whirring, grinding sound. All my ACD lights are on, of course. Also noticed a vibration in the car at speed, but thought that this was due to the wheels being rotated.

If this pump seizes, what are the effects on the car?

Noticing that almost all of our failures seem to happen in the Snow Belt, and we see the issue with the summer heat.

 

not much happens if it stops working, your diff just becomes "open". You won't spontaneously combust

 

Chances are you won't be able to feel the pump vibrating since its dampened and suspended by sheet metal. That sound you are hearing might very well be something else. If the pump stops working you essential have a FWD Evo. There will be no power in the rear wheels and the understeer during turn-in and mid corner will be more apparent. However, most people won't notice this as many have stated "they feel no difference."

 

Do you have anything to back that up? I could floor it in 2nd while my pump wasn't working and there was no wheelspin, so I seriously doubt the car becomes FWD.

Like I said, the diff becomes "open" so it won't lock to maximize traction, but it doesn't go as far as being FWD.

 

My lights are also on, is there a how to test the system?

 

Ummmm, no. It won't turn into a FWD vehicle. The torque split will still be 50/50. ACD also doesn't help the car oversteer. You are confusing that with AYC, which the USDM IX does not have. The only thing you will loose is the lock up of the center diff which may and may not be noticeable depending on how hard you drive.

 

I'm not confusing ACD with AYC. If you jack up the car and run the car while holding (while the pump is not functioning or when the hand brake lever is pulled) the rear wheels you will notice no AWD in the system; the front wheels simply spin while the rear wheels stay perfectly stationary.

You are correct in stating that the center differential remains a 50/50 torque split however, the only way the torque is even transferred is by the friction created from the clutch pack within the transfer case due to the hydraulic pressure which the pump produces. The lack of pressure will result in the clutch pack's inability to mate and create friction thus not being able to transfer power to the rear under conditions which produce reactive forces from the rear wheels. In other words, if you produce non-uniform torque from the front and rear wheels the torque will not be transferred. Therefore the ACD pump is required to provide hydraulic pressure to the clutch pack to provide the possible transfer of torque.