Join Date: Nov 2009
Car: 2001 Legacy OBW 2.5
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In any event, the flashing AT Oil Temp light indicates that the Transmission Control Module (TCM) has detected a problem and is trying to tell you about it. Here's the procedure for interrogating the TCM for the 2002 Impreza (all variants). It's one of those secret handshake procedures reminiscent of the pre-OBD ECU days. I swear I'm not making this up.
1) Warm up the engine
2) Turn the ignition switch OFF
3) Turn the ignition switch ON
4) Start the engine
5) Drive the vehicle at speeds greater than 12 MPH
6) Stop the vehicle
7) Depress the brake pedal and move the gear selector to "1"
8) Turn the ignition switch to OFF
9) Turn the ignition switch to ON
10) Move the gear selector to "2"
11) Move the gear selector to "1"
12) Move the gear selector to "2"
13) Move the gear selector to "3"
14) Move the gear selector to "D"
Now examine the AT Oil Temp light again:
If the light's blinking 4 times a second, then the problem is most likely a power supply or ground problem.
If the light's blinking 2 times a second, then the TCM believes all is normal.
If the light's on solid or not on at all, then there's a problem with the light's circuit.
If the light's blinking with one or more long (1.2 sec) pulses, followed by one or more short (.2 sec) pulses followed by a 1.5 sec pause, then you're seeing a TCM diagnostic trouble code (DTC). The long pulses indicate "tens" and the short ones indicate "ones" so you add up the number of long pulses to get the left digit of the DTC and you add up the number of short pulses to get the right digit of the DTC. DTCs are two digits long (e.g. 23, 36, etc.). The end of the "ones" is indicated by a 1.5 second pause. Then, if that is the only DTC stored, it begins repeating that DTC with the "tens" again. However, there may be more than just one DTC stored, in which case they are spit out sequentially with 1.5 sec pauses between them, until the whole sequence repeats again.