MeDuncan

Hi to everyone. I like to hear from other members who have had problems with their auto trans. My transmission refuses to shift out of first gear when its put into D3 or D4. No indicators light up to say anything is wrong and there are no D codes appearing when I check. It drives fine manually in 1st and 2nd.
Before it decided to stay in 1st I noticed that the gear changes were getting less smooth and the revs were getting higher to get the transmission to shift up.
I've been going over the manual and I think the possible problem lies with the Clutch Pressure Control solenoid valves A and B - primarily with A either becoming jammed or else the CPC solenoids are simply not being told to activate.

My thinking is that these solenoids mimic exactly what I would do with a manual transmission ie my left foot pushes the clutch in (same as CPC solenoid A activating with B off) and then I change gears (combination of shift solenoids A, B, C changing their ON/Off configuration) then letting out the clutch (same as CPC solenoid B activating with A turning off).

I think I'm right or have I gone off the track entirely?

Checking these solenoids is fairly easy though taking apart is another matter, so before I start I'd like some feed back if possible.

MAD_MIKE

No. Torque converters(fluid couplings) are what replace the clutch in a typical automatic transmission.

Linear solenoids are what take place of the throttle valve cable on Honda's(vacuum modulators on older cars). Rather than having a direct physical connection from the pedal, the throttle input control(TPS) is relayed through the PCM to the output of the linear solenoids for the desired pressure regulation/shift point. IIRC the two pressure sensors for 2nd and 3rd affect how the linear valves work. If they are defective/leaking/clogged(they have screens on the tips) this can also affect how the trans shifts(or doesn't).

If your PCM does not know what the throttle angle is(faulty TPS sensor) the PCM may not command an upshift. Common fault with a bad TPS on 90-97 AT Accords is the trans will not upshift under normal driving. Floor the pedal(WOT) and the car will upshift through all the gears, but you will be going ludicrous speed.

Linear solenoids have some adjustment but require the correct pentagon shaped tool and pressure gauges to verify correct pressure output.

Verify your TPS output voltage is smooth and has a linear change. If there are any breaks or voltage drops, this will affect how the transmission is commanded to shift. With Honda, if the TPS goes bad the default is to not to command an upshift.

If you are retrieving codes via the two wire(OBD I) blue connector verify the CEL and D4 lamps illuminate when intially turning the key to II(ON). If they do not the lamps may be burnt out. For both OBDI and OBDII methods of code retrieval verify that the PCM memory fuse is not blown. If it is, everytime the key is turned off the PCM will not save any codes. A quick check to see if memory works is to disconnect a sensor pigtail while the engine is running, setting off the CEL. Reattach sensor pigtail. Turn engine/key off. Wait a few moments, turn key to II(ON) and see if the code is still saved in the memory. If yes, memory works. If no, memory is not saving.


If you do have the service manual, after verifying the basics, fully charged battery, clean and tight batt connections, no damaged wiring, full sump in the AT, correct idle rpms, etc. Check the actual pressures of the various circuits in the trans with a gauge.

MeDuncan

Thank you MAD MIKE for the information. As you can see I'm not clued into automatic transmissions but I'm learning. I took the car for another test this morning and discovered that it is shifting through the gears but only when the revs of the car are over 3000. This strikes me as being in line with your information and so I'll need to test my TPS sensor.