OGardener

My auto tranny goes into "safe" mode every so often. It thinks there is something wrong and stays in third gear. The d4 indicator stays on even if another gear is selected (it's indicator light is on too). I changed the fluid (clear, red - in fine condition). Any thoughts would be greatly appreciated. Thanks richard

jeffcoslacker

Hopefully that means something specific to those familiar with Honda trannies...because it sounds like a can of worms to me...

I'd be looking at the connectors from the TCU to the PCM, and all the way out to the tranny, esp where they pass through the firewall, there's usually a big main connector point where the interior harness and the underhood harness meet at a connector block in the firewall...make sure you aren't loosing your solenoid control and tranny telemetry there intermittantly, maybe shoot some WD-40 into them and reconnect, etc...

Some GM models will default to D3 when the alternator output has dropped below a certain point...you aren't seeing dim lights or slow flashers or anything else when it happens, I guess?

jeffcoslacker

PS, not a flashing D4, right? If so, see sticky post on top....

OGardener

No its not flashing - solid green. In fact when the running lights are on and the other gear indicators are dimmed the d4 is still bright

OGardener

PS no problem with low voltage.

jeffcoslacker

Hmmm. I feel like that alone should tell me something, but I've been awake for over 24 hours right now, and I'm about as sharp as a golf ball...

Hopefully someone will know...I'll get back to you if not shortly...

efinmolloy

i have the same problem only i'm more leading to believe that the clutch went in the transmission. Indicator light shows D4 always. to drive i have to put it into 2nd gear the shift to 3rd/D3. D3 doesn't allow it to shift it just goes to 3rd. So no 1st or 4th gear. I would love to find out if its electrical but everyone i talk to say its mechanical....

jeffcoslacker

You could unplug the TCU and drive it...that's what I do when I'm wondering if it's solenoid control or hard parts/valve body mischief...without the TCU it defults to hydraulic control, shifts at preset points without regard to vehicle load, etc...if it hits all the gears and shifts well like that, you can pretty much expect to find a stuck solenoid or defective TCU...

starynight

It's pretty famous to 90-93.

Your TCM is hosed. Honda has a TSB for exactly this problem. Besides the solid green D, you can verify by doing the following tests (they are related to the same parts)

1. when you depress the brake padel, there should be a light click from under the shift stick if the TCM is good. I bet there is none on yours.
2. Put the gear in P with engine off. Turn the key on, but don't start the engine. Now, without stepping on the brake, you should be able to move the shift stick out of P (you are not supposed to be able to without this problem).

If you take the TCM apart, you will see 2 resistors burnt, caused by maybe a dry capacitor. Replace the TCM will fix the problem. New about $600. Junk yard about $60-$125.

Good luck.

OGardener

You're right! The transmission can be shifted out Park without touching the brake. So... it might not be just a bad sensor... wishful thinking I guess
richard

jeffcoslacker

That's a cool little trick...I gotta file that one for future reference...

HondaAccord1

Im having this problem too, I got a brand new TCU with leds on it put it in and still have this problem. The Tcu led light blinked 8 times and I tried looking it up and it only told me to check the Shift Control Vavle B. I have not replaced this yet but im just wondering if anyone else out there has done this yet and if it worked before I pay more for parts I don't need.

91 Accord LX Automatic

jeffcoslacker

You're the one with first and third missing, right?

That makes sense, there's a solenoid stuck in the energized position, that will override the valve body operation even if you disconnect the TCU...if you disconnect and both are at rest, the valve body is free to do as it will, but with one stuck open, it is forcing odd shift patterns

There two shift solenoids, and they work like binary code, combinations of on and off do diferent gear engagements, like (I know this isn't right, but for example):

on/on first gear

on/off second

off/on third

off/off fourth/OD

So if one is stuck, it would negate the operation of two gears, same as you are seeing.

I think you've found your problem. Good luck, they are inside the valve body area, get a good manual, some valve body disassembly is required to replace them...

HondaAccord1

So should I replace the Shift Control solenoids? Thats right there on the tranny and take off with two bolts right ? then plug it right back up.

jeffcoslacker

I don't know on an Accord...the ones I've done (Toyota and domestics) were inside the pan, in the valve body area. You need to get a manual. This isn't to be taken lightly. If they are external like you're thinking, that's sweet. Wish they all were...