UWMU

I have a 1998 Acura 2.3CL automatic with 80,000 miles. The other day I was on the freeway and the D4 light started flashing.

When I got off the freeway, the car was really slow to accelerate. When I shifed it from D4 to park, the transmission would clunk when going over Reverse or putting it into reverse. It shifted fine once I got to 10-15 mph and was fine once it was up to speed. Here are the codes it gave:

P1768 - Pressure control solenoid valve A circuit fault
P1753 - TCC solenoid valve circuit fault
P0753 - Shift solenoid A circuit fault
Codes for front and rear O2 sensors

On my way home, the alternator died and I replaced that yesterday. The transmission codes are still there. It seems like a weird coincidence for both the alternator and the transmission to go at the same time.

Do you see any relation between the two? Could having a bad alternator cause the transmission solenoids to go?

I'm also wondering whether the transmission is going or whether its worth it to fix the solenoids first. Thanks for any help!

tpot90

I believe this is a common problem for yours & my transmission. I've seen this reported numerous times, but I still don't know the correct answer as to how to go about it. Good luck. I'll be keepin an eye on this thread.

UWMU

I searched the forum and saw some other people post those codes but with no resolution. Most people seem to jump the gun and say get a new transmission, but I haven't had any problems up until now. Also strangely, my battery light is either dead or disabled, so who knows how long the alternator problem was going on without me knowing about it.

UWMU

Problem solved: ECU fuse was blown.

This exposed one huge design flaw: when the ECU fuse goes, it takes the battery light with it. Had I seen the battery light on, I wouldn't have driven it, and wouldn't have ended up on the side of the expressway with a $250 towing bill.

It seems pretty absurd to engineer it so that the warning indicator light for a system goes out when the system dies!

shibbywhitedude

I'm confused as to how a fuse would fix a slipping transmission?

YeuEmMaiMai

ECU problems = incorrect mainline pressure (a linear switch) switch not working correctly = incorrect pressure = slipping. Good way to kill that trans quick but thankfully he corrected the issue with the quickness

UWMU

Well I still put about 50 miles on it after noticing the problem. Luckily most of it was on the expressway so not a lot of shifting was involved but I did have to do some city driving to get to the auto store and back, so hopefully that didn't cause too much damage.

tpot90

My D4 light isn't on, but my 2.3 auto had been slipping from first to second at rolling stops, etc. No battery light--could your same fuse be casuing this problem? What fuse number was yours?

UWMU

For me it was the 7.5W ECU fuse. But if that's the case for you, your alternator shouldn't be putting out any power and your car would be running off the battery. Check out your fuse of course, but it seems like a different problem. And my transmission never slipped, it was just slow to accelerate and was really rough in shifting from Park to Drive or vice versa.

tpot90

*noted. thank you.

UWMU

Well I keep blowing the 7.5W ECU fuse. I was sure it was the alternator because it got to the point where it would blow that fuse as soon as I turned the ignition on. So then I put in a new alternator and drove about 25 miles before I blew the fuse again, triggering the D4 light and transmission codes. So it doesn't seem like the alternator. Do you think it's the solenoids that need to be replaced?

UWMU

I've unplugged just about everything to try to locate the source of the circuit load. I've unplugged all of the shift solenoids, the field wire to the alternator, the cruise control, and it still is blowing the fuse, so I'm guessing it's a wiring problem. I would unplug the ECU to rule that out but you can't start the car without it plugged in. Anyone else have any ideas?

redbull-1

It is probably a short in the ground to the Blk/Yel alternator wire. This will cause the different codes. Repair the damage wire insulation and replace the blown fuse.

UWMU

Thanks for the info, Redbull. I looked and couldn't find any apparent damage to the alternator wires, but that info seems right on point since those are the exact codes that I'm getting.

I have a used ECU that I found for $50 on the way and am going to swap my current one out to see if that's the problem. I called an Acura dealer and they said all their diagnostic manuals call for an ECU swap first; if not that, then start looking at wiring. I'll post if that's the fix, since it seems like enough other people have had this problem without any clear resolution.

UWMU

OP here again. Just in case this problem happens this happens to anyone else in the future, it was a shorted rear O2 sensor that caused all the problems. I replaced it a few weeks ago and haven't had any problems since then. Thanks everyone for your help!

Wolken746

So I have a 99 cl f23 with the same problems as your 98. The o2 sensor being shorted causing above problems makes sense due to my o2 sensors were throwing codes when I first got the car. They cleared out or something and eventually fixed themselves until now my tranny seems like its slipping and my alternator quit after about 20 miles. Im going to swap both o2 sensors and hopefully fix all my problems, thanks for all the info and time saved.