Bronco II A4LD OD problems

[EB Bronco ii]

I have a 87 Ford Bronco II and replaced the trans with another 87 A4LD and it shifts through all gears just fine but when I shift it into overdrive it doesnt want to shift into overdrive.Was just wondering if anybody might be able to give me any tips as to what might be causing this thanks.

 

[EB Bronco ii]

Also when im driving down the road and let off the gas the rpm's drop off to 1000 like it's in nuetral then when I give it gas it feels like it kicks back into gear.Any help on either of the issues would be great.

 

[JK080]

4th and Lockup are controlled by the computer. I would check the case connector to make sure its plugged in, then check for voltage on the center wire of the case connector harness with the key on.

The center wire should have 12 volts and computer grounds the front one for 4th and the back one for Lockup.

 

[EB Bronco ii]

Im guessing its the two prong plug located on the front drivers side of the trans right.

I think mines different than the one your thinking of mines a 87.

So is overdrive and lock up both stiil controlled by the two pin plug or is it different than the three?

 

[EB Bronco ii]

OK so I went out with my scanner to see if I could pull any codes today.Key off engine running (KOER) checked out fine no codes but I did pull a couple for key off engine off(KOEO) and continuous memory(CM).First was a (KOEO)number 86 Adaptive fuel limit reached or 3-4 shift solenoid circuit failure.The second was a (KOEO) and (CM) and it was code 95 Fuel pump secondary circuit failure.

Im not sure what the deal is with the fuel codes the truck runs fine also im kinda confused about the 3-4 shift solenoid circuit failure being that I have a older 87 A4ld I thought it was controlled by hydrolics and not electric.

So at the moment I still have no lock up for the TC and no overdrive im still new to this rig so if any body could help point me in the right direction it would really help thanks.

 

[EB Bronco ii]

So I checked to make sure the case connecter was plugged in and it was so I tested to make sure the red wire was hot with the key on and it was so im thinking the reason I have no lock up is one of two things the lock up selonoid isn't working or im not getting the signal to ground it from my computer.

 

[MrShorty]

Any chance the PCM has been replaced at some point? As you noted, the earliest A4LD's ('85 to '87 by most estimates) only had two wires going into the transmission to control the torque converter lockup clutch (TCC) -- 3-4 shift was hydraulically controlled (governer balance between engine vacuum and line pressure is how I think it works). If the PCM is looking for a 3-4 shift solenoid, that suggests that the PCM might be from a newer year truck (or you '87 was late enough in the year to pick up a two solenoid A4LD). At this point, I might first be interested in determining exactly what kind of configuration your BII is supposed to have. Is the PCM wired for a two solenoid transmission? Is the transmission a one or a two solenoid model? '87 is right at the transition, so sometimes you get odd configurations. It is also 25 years old, and parts could have been carelessly replaced.

 

[EB Bronco ii]

It was recentlly replaced I swaped my shorted out one for the one out of my parts bronco wich is also a 87 the parts bronco is a XL and the one I drive is a Eddie Bauer.The Eddie Bauer has electric t-case and hubs and the XL has manual thats the only diiference ive noticed so far.

The trans and the bronco are one selonoid models two prong plug for the TC lock up.

Also I was trying to think of a way to test the lock up selonoid to see if its working one way I came up with is use a spare male piece of the plug with the wires cut plug it into the lock up seloniod and have the plug hooked to a alrenate 12v source lift the truck off the ground engage it in gear bring it up to speed let off and ground it to see if the seloniod is acutaully working.Might be kinda confusing the way I explained it here's a link were I got the idea from.
http://www.atraonline.com/manuals/general/tetdv/tetdv-c4e.htm

If there's a easier way to test the selonoid please let me know.

 

[JK080]

The ATRA link is a good way to check to see if you can get lock up, I would drive it to check rather than with the wheels off the ground. TCC would be very hard to detect that way.

As for 4th gear, if you do have a one solenoid (TCC) valve body then the 3-4 shift is controlled by governor pressure.

A couple of tests for you to try.

Check the overdrive band adjustment, it should turn in about two turns before it tightens, if it doesn't tighten it might have a broken band. If it tightens leave it tight and set the vehicle back on the ground, start the engine and select manual low, if the transmission is in a bind that tells you the overdrive planet is not broken, (do not try to drive it like this, just want to see if it moves or binds). If it moves the planet has broken or stripped.

Set the band adjustment back out two turns and raise the vehicle off the ground, have someone get in and run it up to around 50 mph and see if you can turn the band adjustment screw by hand, if you cant turn it by hand that means the valve body did its job and the servo has applied the band and the transmission is working hydraulically. The problem will be with the planet.