I swapped a tranny in an automatic 91 Accord EX. Before I started, the car would barely pull, S light on dash stays on (regardless of the switch), battery light on, alternator pulls battery down to 6V, shows 6V at the stud on the output of the alternator. Got the swap done with a tranny from a 92 (swapped one sensor on it). Also put remanufactured alternator on it. Started the car and at first had some trouble shifting. S light was still on. I unplugged the TCM for a few minutes, then plugged back in. The car started and ran fine for about 20 miles.

All at once, speedometer quit, S light flashing constantly, battery light on. I unhooked the battery cable, and the S light cleared. Battery light still on. Voltage at the battery is 12.0V and does not change when revving motor. At the stud on teh alternator, it shows 12V, then when you unhook the wire at the fusebox that goes to the alt, the voltage on the stud drops to 6.0V. The S light clears with the key if it comes on while driving. The tranny does'nt mess up though, it shifts fine. I did jump the harness under the dash at the S light flashed a code 4. I don't have a service manual to look that up so no idea what it means.

Has anyone had any experience with this? I also put the meter probes on the alt and unplugged the harnesses on the tranny one by one with the car running to see if the voltage changed, but it did'nt.