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PO743 Fault Code: Torque Converter Clutch Circuit Electrical Issue - 2002 Dodge Caravan 2.4L

Model: 2002 dodge caravan Fault Code: P0743 Posted: 2010-01-07 19:49

I'm experiencing a PO743 diagnostic trouble code on my 2002 Dodge Caravan with a 2.4L engine, indicating an 'Electrical Fault in the Torque Converter Clutch Circuit'. I'm trying to understand how to diagnose and fix this issue. The problem started after my battery died. When I used a jump-start battery box (without knowing proper procedures), the speedometer spiked from 0 to 120 mph and the gas gauge fluctuated wildly. After recharging the battery overnight, the vehicle wouldn't start properly, and when it did, the gauges behaved erratically again. I replaced the battery, but the same symptoms occurred. Now, the check engine light remains on, and the gear indicator no longer shows the current transmission gear. Based on this behavior, I suspect a wiring or electrical fault in the torque converter clutch circuit. I'm currently looking for a fuse or relay related to EATX (Electronic Air Transmission) that might be faulty. A scanner would likely show communication failure with the TCM (Transmission Control Module), which could explain limp mode and the loss of gear indication. Any advice on where to start troubleshooting would be greatly appreciated.

Related fault codes
P0743
Comments (4)
Anonymous 2010-01-07 21:00

The most common cause is an open circuit in the torque converter clutch electrical path—locate and repair any broken wires or loose connections in this circuit.

Anonymous 2010-01-08 09:19

Thanks for the insight, Jeff. My issue began after using a jump-start battery box improperly. When I tried to start with jumper cables, the speedometer jumped from 0 to 120 and the gas gauge fluctuated. After charging the battery overnight, it lost power again. I replaced the battery, but the same gauge issues occurred during startup. Now, the check engine light stays on and the gear selector doesn't show which gear I'm in. This suggests a deeper electrical issue—likely related to the EATX circuit or BCM (Body Control Module). I’m now systematically checking fuses and relays labeled 'EATX' as they control communication between the TCM and BCM. If the TCM isn’t communicating, it will enter limp mode, which explains why the gear indicator fails to show position.

Anonymous 2010-01-08 17:35

Using a jump-start battery box is fine if connected correctly—however, a dead battery can cause erratic gauge readings due to power surges or module reset. The BCM often resets when voltage returns, leading to temporary gauge malfunctions. Look specifically for an EATX fuse or relay—it controls the TCM circuit. If the TCM isn’t communicating with the BCM, it will enter limp mode and fail to send gear position signals. This is why the gear indicator doesn't show current gear. A diagnostic scanner would confirm TCM communication failure, which directly correlates with PO743 and limp mode behavior.

Anonymous 2010-01-12 09:41

Thanks again, Jeff—your detailed explanation has been incredibly helpful. I now understand the root cause better and have a clear path to follow. Have a great week!