Been awhile since I've been here. The last fixes took care of my problem for over a year, but now they're baaaack...

Symptoms:
1) D4 light flashing constantly
2) In D3 or D4, it will shift from first to third gear automatically (or fourth? - hard to say) I can manually shift to second-it always works
3) In D3 or D4, tranny will downshift to first when coming to stop, but will not downshift at all when I accelerate hard
4) In D2, will take off and stay in second as long as I don't select another gear
5) TCU codes used to read 1,2,7 and 8. Now it flashes continuously with remanufactured unit installed. No pause, no long flashes, just continuous blinking

What I know and what I've done:
* resistance measures around 16-22 on all solenoids. I have not measured while hot as others have recommended.
* solenoids will click when current applied to them, although not all at same intensity
* Honda ATF fluid, replaced last year after fixing it then, is still bright red, does not smell burnt and was between marks on dipstick
* I bypassed connectors to shift solenoid, ( I had bypassed the lockup solenoid connectors last year, which seemed to do the trick - those were carboned out) I used regular quick splice connectors - the kind you clamp around new wire then insert the "bypass" wire, clamp down on the two-toothed metal splicer, then close with cover...are these good enough for this purpose?
* broke down and installed a remanufactured TCU upon seeing mine had white petroleum-ish goo on back side of circuit board. I also noticed the circuits near the capacitors and resistors I had previously replaced seemed to be washed out and possibly not carry sufficient current

What to do?
If I find the wires at the TCU that correspond to the solenoids, do I measure at the wiring harness or the pins in TCU? Should that resistance also be 12-24?
If there is a short in the wiring, how the hell do I find it?...the wires disappear shortly away from solenoids.
If I find a short, do I have to replace the whole harness?
Where else can I look? Other people in forum have had results replacing vehicle speed sensor. The reason I bring this up is that two or three times over the last five years the speedometer went haywire for a day or two. I had ignored this solution as I figured the CEL would flash a code if the sensor was bad?

I currently drive in stop and go traffic about 150 miles/week. I know I shouldn't have bought rebuilt unit til sure it was bad, but I rely on my car for work and I was desperate. Can I use the car like this without damaging it until I find solution? Please help!

Thanks in advance, with a special call to poorman212 who helped so much the last time

 

Have you tried resetting TCM by pulling BackUp fuse for 20 secs? No change or what?

Yes, resistance of lockup solenoids should be same at the TCU connector (disconnected not backprobed). If resistance shows a short or open, then begin to worry about finding it. Most likely will show correct ohms.

Are you sure you are shorting the service check connector? Check for codes on LED of TCM through view window in ECM/TCM cover. The LED will flash TCM codes w/o the service check connector shorted w/ keyswitch ON. LED is right of center of cover.

good luck

 

Yes, I failed to mentioned I had pulled the plug several times. The D4 light would start blinking as soon as the tranny tried to shift to second.

I will check ohms on connector at TCM. I'm really not a pro at this, I just happened to buy a multimeter the last time in the hopes of getting somewhere...Would a lower number indicate a short? How does an open differ from a short, and how would that translate on the meter?

I'm pretty sure I'm shorting the correct connector. That's how I got the codes the last time, but I'll definitely check the LED. I had forgotten that was available. I will post as soon as I do.

Do you know if the speed sensor should show a code on it's own?

BTW, I forgot to also thank you for all your help the last time. Thanks

 

An open is indicated by infinite resistance, same reading as w/ both probes not touching. Short is zero resistance, same reading as probes touching. Some digital multimeters indicate an open w/ OL, which I presume means OpenLine. Short will be very near zero resistance, but probably not exactly zero.

Yes, speed sensor sets both a TCM code 4 and ECM code 17.

good luck

 

Recheck the new TCU for burt cap's.

Next, be sure the "connectors" to the shift/lock up solenoids are clean, female and male side. I've seen some of these build up "dirt and that" in the connectors and cause issues.

 

Thanks... I will pay attention to that the next time. I'm attaching picture of type of connector I've used:
Quick Splice Connector - 18-14 Gauge Is it possible this doesn't make good enough connection? The one I used last time lasted for a year, so I didn't think that was it, but I'll use something else if you think that might be it.
Unfortunately I got called back to work and haven't been able to do much.
I did make a major SNAFU before I posted the other day. I didn't reattach the solenoid connectors well before checking codes, which is why I think I was getting the constant D4 flashing. Made sure they were connected today, drove around, still same symptoms as originally mentioned, but went back to codes 1,2,7,and 8, and the only other thing is the ECL light was on constantly. I took out the 7.5 fuse for a minute, drove it around, and it the ECL didn't come back, and I only got code 7....
I also tried to find a blinking LED on TCM/ECM and could not find anything. I read somewhere that that would indicate no power to unit, but if I'm getting codes, I have to have power, right?

Haven't gotten around to checking wiring harness at TCU for resistance. I'll try that next and post. As for opening new, remanufactured unit, not only does it have labels that say warranty is void if opened, but they also failed to tell me that the price I paid did not include a core charge. In very small letters in the receipt it also says the core "is subject to their standards of rebuild-ability" I haven't decided if it's worth opening yet. The other thing is the last letters on it are different than mine. Mine says 3LX while the other one I can't say cuz it's mounted and I have no time to look it up before I go to work today.

Sorry for being so long winded, but I want to give as much info as possible to try to pinpoint problem.
Thanks for all the help.

 

Those type of splice connectors work well as long as ends inserted are cut flush to insure good wire to be pinched by connector knife. No way to be certain you have a good connection unless you test the line w/ VOM.

All those trans electrical faults is very unlikely unless harness damage or computer damage.

Hopefully, you're repaired TCM is still under warranty. It looks likely cause of problems.

good luck

 

My two cents....I check the connection and wrap it with tape. Water, dirt and that flying around under the hood could get into that connection.

 

I'll double check the connectors again. For now all I had time to do was check resistance at wiring harness of TCU. I did get a lower reading (10.2) on blue/yellow wire, so I'm thinking that might be it. I'm attaching picture of harness in the hopes someone can let me know if I'm reading the right ones.
I'm also attaching the wiring diagram from my Haynes manual which leads me to believe they are the ones for the shift solenoid, which according to the TCU code 7, would be the problem.
If indeed it is, I need to bypass that wire temporarily to see if it works. Problem is, I can't detach it. I've used all sorts of pins to release it, to no luck. Does anyone know how to detach these? The other option would be to cut the wire, but that would be a pain to splice in those cramped quarters.
Any ideas?
Thanks

 

I think, if you use a small "jewelers" screwdriver (flat head) from the female side of the connector at the top, that will allow the "tab" to be pressed down enough to remove the wire from the connector. A "pin" or small wire paperclip might work