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Old 02-20-2019, 10:08 AM   #1
Jdeck
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Default ABS Disabled with DCCD - 2005 STI

I've done quite a bit of searching and haven't nailed down an answer. Car is a 2005 STI. Background is that I have been racing on the Ice/Lakes and need to disable ABS for obvious reasons. For the past year, I have been pulling the ABS fuse in the main fuse box under the hood to accomplish this. It's unclear to me if there is a actually a way to get the DCCD to work 100% with ABS in a disabled state. Ultimately, I don't care if Auto mode works when I'm on the ice. I am only concerned with the ability to turn the DCCD manually all the way to the rear (down on the dash). At one point over the past weekend, I got stuck in a snowbank (). I put the DCCD in lock mode and my buddy confirmed 100% that one wheel wasn't spinning at all, that to me is fishy and I wondering if my DCCD is not really working with the ABS disabled.

Any help is appreciated. Thanks in advance.
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Old 02-20-2019, 10:40 AM   #2
Crazyced
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Quote:
Originally Posted by Jdeck View Post
I've done quite a bit of searching and haven't nailed down an answer. Car is a 2005 STI. Background is that I have been racing on the Ice/Lakes and need to disable ABS for obvious reasons. For the past year, I have been pulling the ABS fuse in the main fuse box under the hood to accomplish this. It's unclear to me if there is a actually a way to get the DCCD to work 100% with ABS in a disabled state. Ultimately, I don't care if Auto mode works when I'm on the ice. I am only concerned with the ability to turn the DCCD manually all the way to the rear (down on the dash). At one point over the past weekend, I got stuck in a snowbank (). I put the DCCD in lock mode and my buddy confirmed 100% that one wheel wasn't spinning at all, that to me is fishy and I wondering if my DCCD is not really working with the ABS disabled.

Any help is appreciated. Thanks in advance.
Just saying, even with DCCD to lock you can still have a wheel not spinning, especially with a helical or very weak clutch diff. Turn at full steering lock at idle speed and play with the DCCD dial. You will know it works if it starts binding.
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Old 02-20-2019, 10:55 AM   #3
Jdeck
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Originally Posted by Crazyced View Post
Just saying, even with DCCD to lock you can still have a wheel not spinning, especially with a helical or very weak clutch diff. Turn at full steering lock at idle speed and play with the DCCD dial. You will know it works if it starts binding.
Sure it is possible. If it helps to add context nothing is worn on this car and if I do that test it does bind as expected. That also doesn't answer my question regarding the ABS system.
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Old 02-20-2019, 11:53 AM   #4
T-37
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It kinda does. Turn off ABS, get on dry tarmac, lock center diff and see if it binds while turning, if so DCCD works with ABS turned off. This may not be true, I don't know, it's just one way to test it.

That's likely not why only one of your front wheels was spinning (or the wrong front wheel was spinning). The front diff in the 05-07 STI 6 speed is a torque sensing (TORSEN) unit which will allow a wheel to free spin if there's no torque on it (wheel in the air or on ice.) The next time you're in a snow bank, try dragging the brakes lightly to create a torque on that wheel and in turn allow the diffs to send torque to the other wheel(s).
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Old 02-20-2019, 12:32 PM   #5
Jdeck
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Originally Posted by T-37 View Post
It kinda does. Turn off ABS, get on dry tarmac, lock center diff and see if it binds while turning, if so DCCD works with ABS turned off. This may not be true, I don't know, it's just one way to test it.

That's likely not why only one of your front wheels was spinning (or the wrong front wheel was spinning). The front diff in the 05-07 STI 6 speed is a torque sensing (TORSEN) unit which will allow a wheel to free spin if there's no torque on it (wheel in the air or on ice.) The next time you're in a snow bank, try dragging the brakes lightly to create a torque on that wheel and in turn allow the diffs to send torque to the other wheel(s).
Actually yeah, I have not really done the test with ABS disabled on pavement now that I think of it. I can test that and try to make a determination. My wheel was in the air so that makes sense. Otherwise, I'm not the first person to have this question (the car is 14 years old) and was really looking for a definitive answer regarding the design of the system.
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Old 02-20-2019, 01:05 PM   #6
mrsaturn7085
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With OEM DCCD control, the TCM and ABS computer are married to each other. If any codes are triggered in the ABS computer, DCCD control will default to open as a failsafe.

The correct answer to OP's question is that you must leave ABS electronically active to keep DCCD functioning correctly. You need to disable it hydraulically by bypassing the lines. The ABS system has no way of knowing that you've taking the ABS motors out of the hydraulic loop.

Some aftermarket DCCD controllers will 'work' without wheel speed inputs (which are provided by ABS on the factory system)... but you lose a lot of control by not having wheel speed input in the DCCD closed loop control. If you just want manual control of locking percentage, you can use nearly any aftermarket system and rip the entire ABS system out.
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Old 02-20-2019, 01:27 PM   #7
Jdeck
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Quote:
Originally Posted by mrsaturn7085 View Post
With OEM DCCD control, the TCM and ABS computer are married to each other. If any codes are triggered in the ABS computer, DCCD control will default to open as a failsafe.

The correct answer to OP's question is that you must leave ABS electronically active to keep DCCD functioning correctly. You need to disable it hydraulically by bypassing the lines. The ABS system has no way of knowing that you've taking the ABS motors out of the hydraulic loop.

Some aftermarket DCCD controllers will 'work' without wheel speed inputs (which are provided by ABS on the factory system)... but you lose a lot of control by not having wheel speed input in the DCCD closed loop control. If you just want manual control of locking percentage, you can use nearly any aftermarket system and rip the entire ABS system out.

Thank you for clarification. Yes, I may install DCCDPro to try solve this but that won't be realistic for a few months. I guess my question is (out of curiosity) is what state that would put the DCCD in if the ABS is disabled? -Confused? -Partially working? -Completely off?
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Old 10-22-2020, 03:02 PM   #8
Jdeck
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Bumping this back up as I would still like to solve this and have a clean abs delete.
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Old 10-22-2020, 09:33 PM   #9
cboggess
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Quote:
Originally Posted by mrsaturn7085 View Post
With OEM DCCD control, the TCM and ABS computer are married to each other. If any codes are triggered in the ABS computer, DCCD control will default to open as a failsafe.

The correct answer to OP's question is that you must leave ABS electronically active to keep DCCD functioning correctly. You need to disable it hydraulically by bypassing the lines. The ABS system has no way of knowing that you've taking the ABS motors out of the hydraulic loop.

Some aftermarket DCCD controllers will 'work' without wheel speed inputs (which are provided by ABS on the factory system)... but you lose a lot of control by not having wheel speed input in the DCCD closed loop control. If you just want manual control of locking percentage, you can use nearly any aftermarket system and rip the entire ABS system out.

THIS! You may also be able to bypass the stock DCCD controller and just install a switch to manually lock the diff. Look up on here how the DCCD system works. IIRC, you can just ground the connection and it will lock.
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Old 10-23-2020, 11:51 AM   #10
Jdeck
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Originally Posted by cboggess View Post
THIS! You may also be able to bypass the stock DCCD controller and just install a switch to manually lock the diff. Look up on here how the DCCD system works. IIRC, you can just ground the connection and it will lock.
Any links to DIY or kits to accomplish the bypassing of the abs lines?
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