Hello guys,
I come here with a recent problem with my 1988 Bronco II. Only about a week or so ago, my Bronco II(2.9L Automatic) started dropping out of Overdrive(never had any signs before hand). I was on the highway and it would just keep falling back to 3rd gear, causing the car to buck and the RPMs to be all over the place, for the rest of the drive I used just normal drive, however the car was screaming...

The main problem here is the falling out of overdrive, I am not sure what's causing it. My mechanic, my father, and I all have ideas as to what it could be, but so far it's not leading to any of them...

The truck shifts great into all gears(except OD now), runs great. The trans fluid is of perfect colour, no smell what-so-ever either.

As of the past day or so, the truck doesn't want to go into Overdrive at all... so I'm really lost now. I cannot afford a rebuild, the truck probably costed me less than a rebuild right now would.

I just ask for any suggestions as to what the problem is and any ways to fix.

I hope it to be simple, or at least cheap to fix as I do not want to have to part with the truck, I have come attached to it over the past 2 years, but really an automatic trans replacement will probably cost me as much as just getting a different vehicle...

Any suggestions are highly appreciated, if you need more details let me know. Thanks.

 

>>If this happens when you give it more gas, then it could be the modulator on the passenger side of the tranny.

87b2guy
87 BII 2.9L V6 auto

 

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87b2guy

This happens no matter what, even when going a constant speed, the truck just keeps changing gears like it knows it's supposed to be in OD, but keeps falling back to 3rd every second.

 

'87- A4LD's had a vacuum controlled 3-4 shift. '88+ A4LD's had an electronic controlled 3-4 shift. 1st thing I would do on an '88 is verify that your A4LD uses an electronic controlled 3-4 shift. If you have electronic 3-4 shift, the first thing to do is make sure the problem isn't in the EEC-IV system. And the best first thing to do there is pull the codes.

 

Question... what exactly does it mean by "pull the codes"? ...and how would I verify exactly if it's electronic or vaccuum controlled?

 

"what exactly does it mean by "pull the codes"? " -- EEC-IV engine management system has several built in diagnostic tests. The results of these tests are output as trouble codes. You only need a jumper wire (paper clip works) and a voltmeter or test light. Ken00 has put instructions in his tech info post.

"how would I verify exactly if it's electronic or vaccuum controlled?" -- Transmission has an electrical connector on the driver's side near the shift lever. If it has two wires (one red, not sure on the other), you have a vacuum controlled 3-4 shift. If it has three wires (one will still be red), then you have an electronic controlled 3-4 shift.

 

Thanks, I don't know if I know where the EEC computer thing is, but... I will definately check to see if it's electric or vaccuum... However at the current moment it is snowing pretty good and I'm not about to lay on the ground at the current moment . I am going to check as soon as possible(maybe when I have to go out to shovel, heh.

 

EEC self-test connector is under the hood, passenger side, tucked down between the air filter housing and the heater fan housing. See Ken00's tech info post (pulling EEC-IV codes) for instructions and a picture of the connector.

 

Mine did the same thing. Turned out to be the selonoid. Some tranny shops will do a free check. Might want to look into that.

 

Probably a stupid question, but did you check the tranny fluid? I'm sure you did, but when troubleshooting, I like to start small. And if your tranny goes bad, I've got a A4LD from a 87 BII I'll sell ya, it ran good for me, I bought a 5spd so I don't need it anymore.

 

[QUOTE=Snake79]Probably a stupid question, but did you check the tranny fluid? I'm sure you did, but when troubleshooting, I like to start small. And if your tranny goes bad, I've got a A4LD from a 87 BII I'll sell ya, it ran good for me, I bought a 5spd so I don't need it anymore.

Yeah, the tranny fluid is perfect, it never leaks or anything always at the correct level, no smell, no discolouration. If I do find that I need a new trans, I will let you know, how much are you asking and where are you located?

To BumpinB2, I will be sure to check the selanoid, thanks.(this was actually our first guess as to the problem)

 

Located in Southern KY, and I'd probably take 250 for the tranny, without the transfer case