Subaru Impreza GC8 & RS Forum & Community: - View Single Post - 4EAT Diff-Lock Switch and Handbrake Mod - "Torquemada Lite"
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Old 03-23-2009, 09:21 AM  
Car: '99 OBS
Join Date: Jun 2008
Location: Metro Detroit
Trader Rating: (2)
Posts: 117

Originally Posted by dSpec View Post
I just did this mod today, but I haven't driven it yet.

The first thing I did was turn the car on, and I noticed that the AT Oil Temp light was blinking. I turned off my car, flipped the switch, and turned it back on. The oil temp light was gone.

Did I do something wrong? I'm about to take a quick drive around the block.
Hi dspec -the blinking AT light is just the TCM's way of complaining. You haven't broken anything, but it does sound like something's not quite right - let's see if we can get everything back on track
Assuming you tested and cut the proper wire, which I'm guessing you did - since the switch is obviously affecting something. My guess is that the TCM isn't happy with your resistor bank, or the wiring to the resistors. Here are some things to double-check:

1. Switch - SPDT or DPDT (ON/ON) - Make sure you didn't get an ON/OFF/ON switch. The center 'OFF' will freak out the TCM.
2. Continuity from the switch 'out' to the resistor bank's ground connection. You did ground the resistors, right?
2a. If the continuity check fails, start at the switch and check each 'section' until you find a break in continuity.
3. Resistor bank impedance (17Ω)

Basically it sounds like you've succeeded in cutting power to the solenoid (a test drive will tell you for certain) but the signal isn't being properly routed to the resistors - which is making the TCM unhappy.

Another possibility is that your car may have one of the other TCMs that Subaru had over the years. I just built a database of all the various permutations of the years and models that I could find. I'll check into that as well.
EDIT: If this is the car in your profile - your car should match the DIY just about 100%. According to my research anyway...
My guess is that you've got a bad connection somewhere.

Feel free to post some pictures of the setup and it's components, and I'm sure we'll get you all sorted out. Also feel free to PM or email me if you'd rather.

Last edited by defcon5; 03-23-2009 at 10:12 AM..
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