BlackLX4

Hey guys, having some trans. issues. When cold and costing downhill in third gear it hunts until I either slow down or shift it into neutral, and then it stops. Also it's starting to shift a little erratically and the 2-3 upshift is sometimes delayed. I had two codes, P0705 (range sensor) and P1739 (3rd clutch pressure switch). I followed the diagnostic procedures, changed the fluid and cleaned and greased the PCM connectors but the problem persists. Any thoughts as to how I should proceed next? It's a '98 Accord LX 4-dr, 2.3L/4AT, almost 262K. Thanks in advance!

MAD_MIKE

The upshift delay is most likely due to the faulty/leaking 3rd gear pressure switch. PCM will not command an upshift to 3rd unless it sees the 3rd pressure switch activated. No pressure signal, either from low pressure or most likely a faulty switch(common problem) then the upshift will be delayed. Look at the pressure switch, if it is leaking then it will not properly register a pressure differential and not activate.
While you are checking the 3rd gear pressure switch, remove the Main Shaft Speed sensor as well, verify it is free of any gunk and material. Wipe it off and reinstall. Its counter part the Counter Shaft Speed Sensor is located behind the transmission mount up on top. Verify this is clean as well. They work together to inform the PCM of the shaft speeds to allow for proper upshifting. If the upshift is harsh or erratic these sensors may be fouled and are not sending a signal to the PCM at higher shaft speeds, this can cause rough shifts and grinding.

1705 means there is a short to ground in the circuit, possibly the switch itself is faulty.

If there was any work recently performed, check that nothing else was disturbed first. Then proceed with correct diagnostics.

BlackLX4

I ran the test on the switch again, but this time I followed the flowchart as if there was battery voltage and went from there. The switch only had a resistance of about 1.29 megohms. It's supposed to be at least 10 megohms. Looks like I'm ordering a new switch.

I'm thinking that battery voltage is considered anything close to 12V. The battery measured 12.3V and the voltage at the PCM connector wires was 11.9V. I think when they mean that there isn't battery voltage they mean something closer to 0V, like a major voltage drop issue.

BlackLX4

Update: I tested all of the solenoids per the FSM instructions and all of them tested good. My only question is this: the service information states that the resistance across either connector of the CPC solenoid A/B assembly should be "about 5 ohms." I got 6.0-6.2 ohms across each connector. When they mean "about 5 ohms," what would be considered excessive resistance? Could a 20% increase in resistance make a considerable difference in the performance of the solenoid assembly, enough to cause shifting issues?

holmesnmanny

Touch the leads together and it's likely you'll get 1 ohm of internal resistance. Subtracting that ffrom the 6 ohms gives you 5 ohms.

BlackLX4

I had totally forgotten that. Lol My dad taught me that some time ago and I had completely forgotten about it. Thanks!

So now where to go with the troubleshooting? I'm still planning on removing all of the solenoids, cleaning them, and reinstalling them with new O-rings and filter screens. Anything else I could try?

holmesnmanny

Just do that and see what happens first. It could very well be a clogged solenoid filter screen.

BlackLX4

Took out the CPC solenoid pair and the two shift solenoids (B and C) and the screens were perfectly clean, both in the solenoids themselves and in the feed pipes behind the CPC pair. Just for good measure, I cleaned them and carefully blew them out with compressed air, tested them electrically and made sure the plungers were moving freely (which they were), and reinstalled each with new O-rings and the CPC pair with a new gasket. Haven't been able to drive it much but it doesn't appear to have changed much. It may be a little better, though. Regardless, my next plan of action is to check the wires going between solenoid and the PCM for continuity to ensure that there isn't anything wrong with the wiring.