simplex Posted January 28, 2021 Share Posted January 28, 2021 I bought a subaru B4 ,originally it was an automatic transmission but the then owner had converted it to manual, so when I bought it I thought of reverting it back to it's original state of being an automatic , So I changed the gearbox, flywheel etc but the challenge now is that the car seem to be limping ,driving in one gear which is gear number 3, Am not sure now what might be the cause of that,some are saying it must have an Automatic Transmission Module, some are saying the same ECU for the engine manages the transmission as well, So I haven't find a AT module for the gearbox to test whether it's true. NB: THIS SUBARU B4 1999 VERSION IS A NON TURBO Kindly assist me on the way forward Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted January 28, 2021 Share Posted January 28, 2021 On some cars it IS the same ECU, but some pins on the connector need to be jumpered together to switch from one trans type to the other. someone with better info will respond but, look for evidence of a clipped wire or an added jumper wire on the connections from the ECU. 1 Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted January 28, 2021 Share Posted January 28, 2021 (edited) The trans module is separate. The ECU can be changed from auto to manual mode by grounding a pin. Look for wiring modifications and perhaps (hopefully) they just unplugged the trans control module. Locked in 3rd gear is what happens when the transmission computer is unplugged. Subaru, as a general rule, does not use PCM's (powertrain control module) to control both engine and trans. GM has done that since the beginning of the 4L60E, and I think Frod and Chrysler are similar. Japanese stuff tends to have separate modules - which honestly is a pain with the newer stuff since half the problems we see on CANBUS cars are module communication codes. Would be better if they were in one unit. GD Edited January 28, 2021 by GeneralDisorder 1 Quote Link to comment Share on other sites More sharing options...
simplex Posted January 29, 2021 Author Share Posted January 29, 2021 Thanx a lot by sharing such information including general rules of Subaru,confusion cleared, Quote Link to comment Share on other sites More sharing options...
simplex Posted January 29, 2021 Author Share Posted January 29, 2021 17 hours ago, GeneralDisorder said: The trans module is separate. The ECU can be changed from auto to manual mode by grounding a pin. Look for wiring modifications and perhaps (hopefully) they just unplugged the trans control module. Locked in 3rd gear is what happens when the transmission computer is unplugged. Subaru, as a general rule, does not use PCM's (powertrain control module) to control both engine and trans. GM has done that since the beginning of the 4L60E, and I think Frod and Chrysler are similar. Japanese stuff tends to have separate modules - which honestly is a pain with the newer stuff since half the problems we see on CANBUS cars are module communication codes. Would be better if they were in one unit. GD 17 hours ago, 1 Lucky Texan said: On some cars it IS the same ECU, but some pins on the connector need to be jumpered together to switch from one trans type to the other. someone with better info will respond but, look for evidence of a clipped wire or an added jumper wire on the connections from the ECU. Thanx a lot Quote Link to comment Share on other sites More sharing options...
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