A4LD OD solenoid click question for the Trans Gurus: Glacier991, Mr Shorty, Brooklyn

[Jelinski]

Hi to all.
New at posting on forums. Been working on cars for a while.
I hope that I have posted in the right area, and am using the correct etiquette.
I also think that this is a long post, but here’s all the info up front.

I need a bit of advice on the A4LD in my 1994 Mazda B4000.
I hate to bug you all on ANOTHER A4LD OD question, but I want to have an idea of what to look for BEFORE I have transmission parts scattered all over my shop!
Also, I hunted around quite a bit before posting, but I did not see this particular question addressed.

The trans quit shifting into OD.
The electrical system outside of the transmission appears to be OK.
TCC engages at about 45 - 50 MPH.
The PCM commands the OD shift, but… no shift.

Engine off, ignition switch on, the OD electric solenoid clicks when I manually ground the return wire. The OD solenoid click is clearly audible to me when my head is up near the battery. The wire that I ground to get the OD solenoid to click is orange with a yellow tracer. The Ford manual wiring diagram shows this to be the OD solenoid return line to the PCM. The PCM grounds this line to activate the solenoid.

In contrast, I cannot hear the TCC solenoid click, either listening in the open air with my head down under the car next to the transmission, or when using a stethoscope with the probe on the left-front area of the transmission housing.
The wire that I ground to try to get the TCC electric solenoid to click (I cannot hear it click) is purple with a yellow tracer. The Ford manual shows this to be the TCC solenoid return line to the PCM. The PCM grounds this line to activate the TCC solenoid.

My questions:
-Any ideas what specific problem I should look for to fix my transmission?
-Should the TCC electric solenoid be very almost silent, and the OD solenoid clearly audible, or should they both make about the same sound?
-Are they normally clearly audible, or are they normally nearly silent?
The crazy part- at least to me- is that the solenoid valve that I can hear click, the OD solenoid valve, is the one on which the function is not working. The one that I cannot hear, the TCC solenoid valve, is the function that is working OK in the transmission.

Recent history: Rebuild
About 2 years ago, then-16-year-old #1 daughter & I rebuilt the transmission using the Ford factory manual and Glacier991’s excellent “My A4LD Rebuild Diary”.
The Diary is well written, and a HUGE source of information! Thanks Glacier!
We installed the Transtec rebuild kit for the steels, frictions, and seals. We replaced the intermediate & OD bands. The low/reverse band looked like new, so we re-used it.
We replaced the intermediate and OD band hydraulic piston ‘solenoids’- the rubber was hard on these. (I think the intermediate one got hard and leaked, then had insufficient force on the band, the band slipped, wore out, & scored the OD of the drum. Also the clutch plates inside this same intermediate drum were welded.)
We replaced the intermediate drum, and of course installed the new steels & frictions using the ones in the Transtec kit.
We replaced the front seal, Loctite’d & staked it in, but left the pump & front bushing alone! (Again, thanks for the advice in the Diary! Kept us out of some BIG trouble!)
We replaced the torque converter with a remanufactured one, and flushed the cooler lines.
We cleaned the transmission and valve body thoroughly.

On the VB, as soon as I removed the cover plate and saw the loose balls and discs (pucks), I thought “Oh S***!” I then took a good, hi-quality digital photo of the valve body. I made a couple of full-page prints of the photo, and labeled and arrowed where each ball and puck was located. This was a big help for us in making SURE the pieces went back where they belong.
Once the balls, pucks and loose parts were removed, we started by rinsing all the passages with carb cleaner, We (carefully! & one at a time) removed the parts from each VB bore, cleaned each bore & the valve parts w/carb cleaner, lubed the valve parts with trans fluid, and reinstalled the components in the valve body bore, making sure they moved freely.

Anyway, got it back together, it ran great for several months.
Note one ‘operator error’ while driving …. I was showing #2 daughter the difference between ‘D’ and ‘OD’, and moved the shift lever from ‘OD’ to ‘D’ at 65-70 MPH, expecting the usual mild ‘drop out of OD’ shift common to Ford cars. I was surprised by a very hard shift down to 3rd! I guess the TCC was engaged! Hope I did not break anything! (But- the hard shift was going into 3rd, not OD! So OD should have been OK.)

Then, one day (I don’t recall how long after the hard OD-to-3rd shift) I drive off, and reverse, 1st, 2nd, 3rd,and TCC are fine. But… no OD.

Diagnostics so far:
-Test drive, confirmed 1st, 2nd, 3rd, TCC lockup are OK, confirmed no OD.
RPM at speed: 2550 RPM at 60 MPH, 3000 RPM at 70 MPH.
-I checked the fluid level (hot, idling in park)- full.
-I checked for PCM for KOEO, KOER, & stored codes- all ‘1,1,1’ codes. (No trans tester, cannot check for trans codes.)
-The cruise control works OK, so the VSS is working.
I’m thinking- Electrical control, hydraulic control, or mechanical?
Got out the wiring diagrams.
-Checked- got 12V at the OD/TCC connector on the trans.
-Pulled the ECC relay in the fuse box that powers the solenoids. Disconnected the connector on the inner fender that carries the ‘return’ wires from the solenoids to the PCM. Checked the resistance from the output terminal of the relay socket, through the harness, through the solenoids, to the harness connector on the inner fender. Both solenoid circuits show right at 30 ohms.
By the way, the color codes (P=Purple, not Pink!) on my B4000 are the same as the Ford Ranger wiring manual, but the connector pin-outs are a bit different!
-With 12V supplied to the solenoids via the relay output pin, tried grounding the return wires one at a time. I could hear the OD solenoid click, but to me listening ‘open air’ from under the trans, and then listening with a mechanics stethoscope on the outside of the case (forward, on the left side) I could not hear the TCC solenoid click. Put everything back together.
-Put the back axle up on jackstands. Back-probed the connectors on the wheel well for the two solenoid-to-PCM return wires. Connected a voltmeter to each back-probe.
Started the truck, put it in OD, wheels spinning in the air. Voltage on the wires from both the OD solenoid and the TCC solenoid showed 12V at low speed, then, as I sped up, each one dropped to near 0V at around 35-40 MPH indicated on the speedometer.

So…. It APPEARS that the PCM is commanding one solenoid to shift the trans into OD, and commanding the other solenoid to lock the torque converter.
But, OD ain’t happening.

Any ideas on what to look for next?
I am hoping it’s a hydraulic control problem.
-The OD electric solenoid valve may have failed or have a piece of crud in it, or
-There’s something somewhere in the valve body- a piece of crud, a clogged screen, or a stuck valve, or a stuck ball. I realize that the thing causing the problem could be pretty subtle and not easy to spot. It would be nice to have an idea of what to look for, before I tear into it.
-or-
-I could have broken something in the OD drum (Ugh!) with the hard downshift,

Any ideas?


Thanks in advance, and

THANKS AGAIN FOR THE A4LD REBUILD DIARY!!
If nothing else, my #1 daughter and I had a good project together!

Jim in Miss’sipp.

 

[MrShorty]

Engine off, ignition switch on, the OD electric solenoid clicks when I manually ground the return wire. The OD solenoid click is clearly audible to me when my head is up near the battery. The wire that I ground to get the OD solenoid to click is orange with a yellow tracer. The Ford manual wiring diagram shows this to be the OD solenoid return line to the PCM. The PCM grounds this line to activate the solenoid.

It surprises me that you can hear the OD solenoid near the battery. I've never been able to hear either transmission solenoid, even with the transmission pan dropped (not sure how hard I tried). Suggests to me that you were hearing something else (EVR solenoid or ???).

Beyond that, I would agree with your assessment that it appears, electrically anyway, the OD solenoid is working correctly. It looks to me that the problem is either hydraulic (crud in the valve body or clogged OD solenoid screen if applicable or valve sticking) or mechanical (broken band or something like that). It seems that the clogged OD screen is fairly common, but it also seems like they didn't put that screen in every A4LD, and I'm not sure if a '94 would have one or not.

 

[BrooklynBay]

Welcome to this forum! Adjust the overdrive band. The part on the side of the transmission that looks like a rubber piston is called the accumulator servo piston.

 

[Jelinski]

Thanks for the Replies!

Thanks Mr. Shorty & BrooklynBay for your advice!

Actions for me to take:

1) Check adjustment of the OD band. (Try the easy fix first!)

If that does not work,

2) Study the valve body diagrams, determine the fluid paths that actuate the OD accumulator servo piston.

3) Drop the pan, remove the valve body.

4) Examine the OD solenoid to see if it is loose or if there is something wrong with it. Thanks Mr. Shorty for the note that you have always found the solenoids to be rather quiet. I checked it once more... I can clearly hear a 'click' -both 'open air' and through my stethoscope- coming from the area of the solenoid when I ground that orange/yellow solenoid return wire! Maybe the click indicates that something on the solenoid is loose and 'hammering' when I energize the solenoid. Again, I cannot hear the TCC solenoid- either 'open air' or with a stethoscope- when I activate it.

5) Remove the VB cover plate. Carefully examine the fluid paths used by the OD solenoid valve & OD accumulator piston. Look for debris, crud, or a clogged filter screen. Check that the valve parts move freely in their bores.

6) Report back on what I find. It might help the next guy!

I'm still rebuilding after the 2005 Hurricane Katrina wipeout, so it will probably be a couple of weeks before I can get a chance to drop the pan. But when I do get into it, I WILL post what I find!

Again, THANKS for your advice, and again, pass on my thanks to Glacier991 for the A4LD Rebuild Diary!




Jim in Miss'sipp

 

[Jelinski]

Hello to Mr. Shorty & BrooklynBay!

Well, I FINALLY got a chance to get after the transmission! (We're still rebuilding after hurricane Katrina. LOTS of stuff needs a LOT of work- Ugh). BrooklynBay, you hit it with suggesting that I adjust the OD band. I turned the adjustment bolt as far in as I dared to... the square head was ready to disappear into the locking/jam nut.... the band never did tighten up.
It appears that I have a broken band, or maybe the mechanical link somehow fell out. I'm thinking broken band, which means I will have to pull the trans to fix it. I don't have the time or energy to do that right now- maybe in another 6 months or so. So, as a local-use vehicle, it will have to get along without overdrive for a while.

Thanks again for your advice, at least now I know where the problem is, and what I have to do to fix it!

All the Best!

Jim Jelinski

 

[BrooklynBay]

Thanks fore the update! Keep us posted on how everything works out after you fix it.

 

[Jelinski]

I'll be glad to!