Only Overdrive/Reverse works on A4LD | Ford Explorer Forums - Serious Explorations

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Only Overdrive/Reverse works on A4LD


September 18, 2010
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City, State
Denver, co
Year, Model & Trim Level
1990 ford ranger 4.0
Rebuilt my a4ld, (because of a no reverse problem). Put back together, following Glacier991 diary and ATSG manuals. The reverse problem seemed to be a stuck valve in the reverse engagement valve. Now it will only go forward in overdrive (has full power in od), but will not move in 1,2, or drive. Reverse works as well. To eliminate a possibility of a cable problem, I am manually shifting it right on tranny, from access in floor. Curious, why overdrive is the only forward gear working, when online researching, most cases from people saying overdrive doesn't work, haven't found a similar problem. Any thoughts appreciated, thanks.

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So you say it will only go forward in OD, do you mean you select OD and it runs through the gears normally, or do you mean it starts off in OD very slowly and doesn't shift?

I select overdrive and it shifts from 1-2, 2-3 normally, but doesn't shift into 4th. If I select drive, 2, or 1 I can get it to barely move, but increasing rpms, completely stops it.

Yikes, you followed Glacier's VB rebuild too or did you use a rebuilt.

Is the converter locking? You should get a slight flare of engine rpm if you drive highway speed and tap the brake (keep your right foot on the gas pedal during the tap)

Yes,I followed Glacier's valve body rebuild guide. No flare at highway speed. The closest symptom of this in the atsg manual says the converter could be staying engaged:
Symptom: Vehicle will move only when the engine is accelerated to a high rpm and transmission selector is placed in overdrive.
1. Convertor clutch shift valve stuck in locked position.
2. Convertor clutch shuttle valve stuck in locked position.
3. Lock up piston in torque convertor will not disengage.
Checked the valves in 1 & 2 and they both moved freely. Wonder if the torque Convertor could cause this problem.

If the converter was locked all the time wouldn't the engine stall when you shift from park/neutral to a forward gear?

Were you super clean when rebuilding the VB? Dirt is it's enemy.

I would be surprised if your converter worked fine prior to the rebuild, then all of a sudden it started malfunctioning after your rebuild. My guess is that you have a issue with your VB.

True, it should stall the vehicle. I will take the valve body out again and clean it (which would be a lot easier than tc). The main bore I had trouble with getting out was bore 216- intermediate servo release, overdrive servo release, and 3-4 backout. Should have left that bore alone as Glacier did on the first valve body rebuild writeup he posted.

Maybe you should consider a VB from Central. I don't mean to sound insulting, just that they test them and guarantee them to work out of the box. You may need a new (new to you anyway) VB if yours is screwed anyway.

Yeah I'll look into it. I got a few extra valve bodies laying around as well.

Thanks for your replies. I will update back this weekend.

No prob, glad to help. let me know how you make out.

Changed valve body out and it is shifting and driving thru all gears. The only problem is the shift points are too high. 1-2 at 2500 rpms and 2-3 around 3200 rpm. The modulator has a screw in adjuster, so I am going to try to find a small elbow screwdriver to screw inwards to try to lower shift points.

Give it a shot. I remember reading in one of the shift kit instructions that the C3 and A4LD modulators are very similar but different. Standby...

An easy way to tell is there is a restriction built into the vacuum connection on the A4LD modulator. One of the results of installing a C3 mod on an A4 is high shift points. Never know.

The thought did cross my mind. The local Transtar supplier is constantly messing up my orders. Wish I would've checked it closer, the top is more recessed on the c3 modulator.

You can access it through the hole in the floor where the 5 sp shifter would come through if you had a manual. I changed mine through there, took me about an hour if I remember correctly. There is also a thread outlining how-to do it.

Might be worth replacing it either way, seems strange that everything works perfect except for the shift rpm. Have you checked your vacuum line and that the engine is producing proper vacuum as well? I am guessing you used a torque wrench on the VB?

Torqued valve body bolts to 96 inch lbs, except for ones at solenoids tightened to 75 inch lbs, (as the Transgo shift kit suggested). Wondering if throttle position sensor could cause this. Getting check engine light codes for throttle position sensor. Pushed cable all the way in towards cab, then pushed pedal to the floor. Moving cable back out seems to affect it.

Meant in previous post adjusting kickdown cable affected shifting.

Did you use the TransGo method to adjust the kick down cable?

The Ford A4 manual diagnostic routine (#311) says the following for Shift concerns. Shift timing, early/late

Improper operation of EGR
Improper speedometer gear installed
Incorrect tire size
Improper oil level
Manual shift cable misadjusted/damaged
Kickdown linkage misadjusted, stuck/damaged
Improper clutch or band application or oil pressure control system (perform shift test and pressure test)
Main control body bolts too tight/loose or dirty/sticking valves
Overdrive clutch damaged
Low/reverse servo damaged
Governor sticking, worn, damaged

That's all I got dude. At least it's working better.

Did you replace the governor? I had to on my trans.

Not sure about the TPS, you could check it with an analog multimeter, or just change it if you are getting a code, you'll have to anyway. I wonder about engine vacuum and the modulator. Usually if the governor is malfunctioning you have to lift off the gas to let it shift.

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Interesting fact I just found in the Ford A4 manual, that the converter lock-up clutch is released hydraulically when the governor pressure is low (or not present) under approx 30 mph... who knew?

Also found mention that the vacuum system, disconnected, plugged, leaking possible for early/late shift timing. Kind of goes along with the C3 modulator possibility I guess.

I'm also a proponent of governor replacement for any rebuild (as is Glacier). Some people think that polishing them can be as effective but I have seen people have to go back in and replace them after polishing. For the money and piece of mind it's a good idea. Also available is a heavier Sonnex weight, 38 mm I think. I added it and liked the slightly quicker shift.