1990 Ranger no Overdrive after trans swap

Tiny
EDISONCOMPUTERS
  • MEMBER
  • 1990 FORD RANGER
1990 Ford Ranger, 4.0L, 4WD, 165K on body, 123K on engine, 100K on tranny.

I recently bought a 1990 Ranger Super Cab with a bad auto tranny and swaped in the auto tranny from my 1990 Ranger Long Bed (bad frame). After changing drive shafts (they're about 2 inches different), the new(er) Ranger won't go into overdrive. Shortly after, it wouldn't shift automatically between any gears, I had to pull the shift lever into 1st, then put it in 2nd, then 3rd or it would stay 1st until it got up to operating temp. My mechanic found the modulator was bad and leaking fluid into the engine throught the vacuum line. He replaced that, and now it shifts fine from 1st to 3rd, but not into OD. I can let off the gas at 60 MPH (engine turning 3200 RPM) and it will drop to ~1000 RPM, but will not go into OD. I had no problems with the tranny in the old truck to the day we swapped the tranny. While the tranny was being swapped, we flushed it and changed the filter, although the fluid wasn't nasty or burnt. Another mechanic said that the computers might be different and I should try swaping them, another said the truck was too old to have a computer contolled tranny and that the kick down cable must be the problem. Any ideas or help would be greatly appreciated!
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Tuesday, November 20th, 2007 AT 6:18 PM

6 Replies

Tiny
AUTOPRO
  • MEMBER
Is the new (second hand ) still good? How do you know?
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Tuesday, November 20th, 2007 AT 6:53 PM
Tiny
JACK42
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Did you swap shifter assemblies? The OD one has a diiferent amount of spots for gears. Otherwise you would have no manual 1st if it was working correctly P through 2nd
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Wednesday, November 21st, 2007 AT 11:18 AM
Tiny
EDISONCOMPUTERS
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Both of the trucks had the OD tranny. Last night I was messing around under the hood, and found a hard vacuum line that had rotted out in 4 places. I replaced that and now at 55-60 MPH it tries to go into OD - a noticeable clunk into OD - if I let almost all the way off the gas, but as soon as I press at all on the accellerator, it comes right out and back into 3rd. I don't know if it was coincidence or not with the leaking line and it trying to go into OD, but the leak definately wasn't helping anything.

Thanks for the fast responses!
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Wednesday, November 21st, 2007 AT 3:29 PM
Tiny
JACK42
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When the modulator was changed, did the small rod that works it get back in there? It is a common thing for those modulators for the pin to not make it back in there, very small, but without it the trans thinks you are on the gas (low vacuum) and wont want to go into OD
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Friday, November 23rd, 2007 AT 7:41 AM
Tiny
EDISONCOMPUTERS
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Sorry it took so long to get back to you, our main PC went down and took 3 days to recover. I wasn't able to get any info on the modulator pin or rod that you mentioned, but with the recent snap of cold weather that we've had, I have found that if I don't warm up the truck for at least 5-10 minutes, I have the no shifting at all issue (it'll stay in first, until I manually pull the shifter into 1st, then bump it up to 2nd, then it'll stay in 2nd the same way if I go right to drive instead of holding it in 2nd till the RPM's where it would normally shift into 3rd).

I already tried kicking it and that made no difference, neither did cursing it out (I felt a little better, though)
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Thursday, November 29th, 2007 AT 3:17 PM
Tiny
JACK42
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Check the rod, sounds like a modulator that isnt working. Trans cant see throttle vacuum so it holds the gears thinking you are hard on the gas
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Friday, November 30th, 2007 AT 7:19 AM

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