92 Accord EX Transmission issues
 

Last week my D starts blinking at me and the transmission drops down to 2nd or 3rd gear and my RPMs shoot up. I did some research and figured it was the TCU. I buy a reman unit that works fine for a week and then my D starts blinking again. This time tranny appears to be stuck in 4th (limp mode). I can manually shift to 2nd. I pull the codes and I have an EGR code as well as the two codes for the Transmission Shift Solenoids. I've checked fluid levels, manually checked both solenoids and I'm getting clicking sounds from all 4 contacts. They looked clean and the tranny fluid looks brand new even though it as 5k miles on it. I'm still getting the EGR code as well as the two shift solenoid codes. Any suggestions on what I should look for next?
Thanks for your time
david9h

So the solenoids check out. Are the wires to them good? Seen posts in the past where the connector/pigtail was bad.

Then open up the TCU and see if any of the components are burnt.

I still have the original TCU and it looked fine. No burnt or leaking capacitors. The reman. TCU looks fine too. I'm not too concerned about the EGR code. I don't think it would be affecting the transmission. Could it? The solenoid pigtails appear to be working. Could there be an issue with the wire harness connections? I haven't checked those yet. How would I check those?
david9h

What codes did you find? They may suggest an alternative explanation.

Two faulty solenoids seems a bit unlikely. Perhaps harness is damaged.

Checking solenoid circuit can be tricky. You're trying to verify that 12V is available when shift signals are commanded. To do this you will need to understand about when shift signals are expected.

I checked my lockup solenoids on Acura 2.5TL by splicing a wire to the harness wire w/a wrap splice connector and rigged a light (ground also necessary) in the cabin. I could see the lockup signals being sent and knew TCU or wiring was not the problem. Problem still exists and is an internal hydraulic fault apparently. Only affects torque converter lockup not shifting.

good luck

The Check engine light is giving me the code 12 for EGR and the transmission "D4" light is giving me codes 1( Disconnected Lock-up Control Solenoid Valve, short or open in lock-up control solenoid valve A, Faulty lock-up control solenoid valve, 7 (Shift Control Solenoid Valve A, and 8 (Shift Control Solenoid Valve B).

That many simultaneous failed solenoids is extremely unlikely, so a common link is likely; damaged wiring, connector. TCU-harness connector would be a prime suspect.

Suggest disconnecting the TCU-harness connector and performing solenoid resistance checks from the connector pins. Resistance is probably a few ohms to 10-15 ohms. I don't have spec w/ me.

If you see opens or shorts in any/all of the circuits you will have to run down the wiring or connector fault by working your way towards the solenoid w/ resistance checks till you find the fault/s.

good luck

please check the connectors......knew I saw this somewhere.

honda-tech.com/showthread.php?t=2860130

Checking the connectors is a good tip. I've checked the connectors attached to the shift solenoid, but haven't checked the Wire harness side. Anyone know of a good way to check this connector?