j894

2000 Accord EX 2.3 automatic
186k miles (Trans was rebuilt around 20k miles ago)

I know the 4 shift solenoids and their locations : the linear shift solenoid, the lockup solenoid(torque converter clutch?), and 2 shift control solenoids.

Can anyone give me a breakdown of the shift solenoids & which one controls which gear shift? IE. shift solenoid A controls 1st-2nd shift, shift solenoid b controls, 2nd -3rd shift? Is that how they are identified for their function?

I need to know which solenoid controls the 3rd - 4th gear shift. I could not find much info about it even after searching.

Reason being, I sometimes have a 3rd-4th shifting problem on cold mornings in which I will get a flashing "D4" light and and code p0780 (It just hangs instead of shifting into gear). This only happens during the first few minutes of running when costing downhill under no load (If I keep it in "D3" I dont get the code). It works fine if your are driving normally on a level road. I also occasionally get a rpm flare/spike in the 3rd to 4th shift also.

It almost certainly seems like a shift solenoid.

I already had the trans shop who rebuilt it look at it, however they were unable to replicate the problem probably due to the different geographical locations; I live in the mountains at the top of a hill (going down a large hill is when the problem occurs), they're 30 miles away in a valley with flat roads. Even after tearing the trans apart last year they couldn't find anything wrong, and won't just replace the solenoid without replicating the problem.

It out of warranty anyway so its my problem.

SOo, can anyone tell which solenoid controls the 3rd - 4th gear shift?

Lost Again

Shift C is for 3-4 or 4-3 shifts.

j894

Thanks for the info.

I ordered shift solenoid C (lower solenoid w/ Brown connector), 28500-P6H-003. Will post the results.

On a side note, even after looking up the parts by my VIN, it still showed Keihin or Denso shift solenoids on majestic honda.

I jumped the gun a little and ordered the Keihin, but what is the real difference between Keihin and Denso solenoids? (denso costs double)

Lost Again

I now realize we are having this discussion on/in two different forums

j894

Well After installing the new solenoid (C) and driving it around for a few weeks, I still have the problem with this code under the circumstanced mentioned.

Anyone run into this before? Can the fluid be due for a change (only 1 year old)?

j894

I took off the linear solenoid to check the pipes for debris as someone mentioned on another forum for a similar problem, but it was all clean including the screens inside the pipes.

The linear solenoid I have does appear a little older. I'm wondering if the solenoid itself is going or the spools inside are hanging up when it's cold. From what I understand these control the pressure being applied to the clutches inside the trans, no?

Can anyone advise replacing it? It's an expensive shot in the dark to just replace using guesswork.

My trans fluid has never been discolored or had any debris in it. I changed it about a month ago (drain/run/refill 4 times) as a precaution but it change anything. Not sure what's going on here but it's annoying, the trans now has 27k miles since rebuild.

j894

Forgot to mention: I've been getting the shift malfunction code more often now (conditions described in my 1st post), even when its a little warmer.

halninek

since you have a CEL code its doubtful the problem is internal leakage or pressure related. were all the clutches and steels replaced when the transmission was rebuilt? also was the internal filter bypassed or?

also id probably remove all the front solenoids and check to be sure none of them are blocked. you can spray em out with brake cleaner and shake them out, then sit em upside down to drain and dry. make sure the screens are clean too. this probably isnt the issue though.

really it sounds like 3-4 clutch wear, especially since it goes away when warmed up. any other symptoms?

j894

No, no other symptoms. Sometimes it flares in 3-4th shift and sometimes not regaurdless if hot/cold. Again the code & light are set only when costing downhill when cold, say under 55*F. If Im on the throttle for the 3-4 shift, it will shift.

As far as I know the internal filter was replaced as well as the unit's steels/clutches when it was overhauled. The fluid has never been dirty or really had a burned smell.

halninek

almost sounds like a tcm issue have u tried resetting? or something to do with the grade logic, which operates based on manifold vac/pressure. id look at vacuum hoses and other sensor connections to make sure nothing is loose.

fiveten

This is straight from HONDA....If you have that code you replace the solenoids only when....


"A/T Solenoid Replacement
Criteria
NOTE: This article applies to ’99–04 Accords,
’01–04 Civics, ’02–04 CR-Vs, ’03–04 Elements,
’99–04 Odysseys, and ’03–04 Pilots.
The diagnostic procedures in our S/Ms were
written before we had solenoid replacement data.
To cut down on unnecessary solenoid
replacement, don’t replace solenoids if any of
these criteria are met:
• The odometer has more than 20,000 miles.
• The vehicle has a reman A/T.
• The ATF is contaminated with friction material
or metal.
• The axle seals are leaking or the differential
carrier bearings are loose.
• The A/T makes grinding or whining noises."

fiveten

The trans has a serial number sticker on the side. Do you have a BAXA or B7XA?

fiveten

If you were to troubleshoot that code the solenoids you would replace would be the "tcc shift "A" solenoid assy and the shift A/B assy. 2 solenoid assemblies the rectangular one with 2 solenoids on the side of the trans and the one at the top with the 2 round solenoids.

j894

Resetting as in unhooking the battery? I normally do that to clear the code.

Also, I originally swapped PCMs a year and a half ago by advice of transmission shop for a 2nd gear problem (wasn't the problem, it was actually the shift solenoid), and I just put that PCM back in not long ago and it still throws the code even though it was never set on that PCM.

I don't think any vacuum lines or connections are loose, I'll have to re-check them.

Mine was rebuild and has over 20k miles . But hasn't had contaminated fluid leaking axles seals, or any weird noises.

Mine reads BAXA

Don't these normally control 2nd gear and the TCC engagement? (I'm just trying to get an idea of what's going on)
I believe these were replaced when I originally had a lagging 2nd gear shift. Now that I think of it I first got the Shift malfunction code not long after they replaced that assembly, but it only happened twice between last Feb and last May (2011), then it stopped until this past October. Not sure if it's related or not though.

Is the TCC engagement maybe the issue in that when I'm going downhill it's trying to lockup for engine braking, rather than shift to 4th like I thought? and because it's not locking up its setting the code?

Just thinking out loud, I'm no automatic trans expert. I just bought a 5sp but I was hoping to solve this before selling it.

All efforts for help are greatly appreciated.

j894

Took off the lockup solenoid assembly today and there was no debris in the screens or otherwise. The transmission fluid has never been dirty or in bad condition since it was rebuilt and I found no sign of debris in any of the solenoids. Is it possible something is still worn in the transmission despite the fact that the fluid has never been contaminated? I know there is an internal filter, but I'd imagine it doesn't get everything.

....Or is this still sounding like an intermittent electrical/solenoid problem?