sorry to revive a dead thread but does anyone have any more info on this issue.
i will be buying a 94 from my neighbor in the next couple weeks and it does not shift out of low. im pretty sure the spedo worked when i test drove it but the trans would not shift from low while in D, 1, 2, or 3 but reverse works fine.
i had a trans from a 95 ready to put in but found out its lockup is controlled by pulse width modulation making it incompatible.
any help gettin this 94 stuck in low back on the road would be greatly appreciated.
i split off your thread - post and started this thread for you.
If you have a problem, post the question with some information in the thread title and these folks here will offer up some suggestions
Have you scanned the vehicle?
What is the history on the vehicle?
Mileage, recent trans repair work or service?
If the speed-O ias not working the system does not knwo the vehicle is moving... since you say the speed-O works, there is another test
You can unplug the trans connector at the case or remove the trans fuse in the panel. This will put the trans into default - fail safe mode. The trans will then be in 3rd gear and would not want to move from a full stop without lots of throttle applied.
That will at least tell you the 3-4 clutch pack is good
In manual 2nd gear, the trans is not in 2nd gear?
Welcome to Hotrodders.com Glad to have you with us
You may have a broken 1-2 accumulator piston, or Electrical problems. Take it to a reliable transmission shop & have it diagnosed, it should cost about $40 sometimes free. They can tell you what's wrong in about an hour, where it may take you three days to diagnose the problem.
Hi Rich, thanks for the warm welcome! First, I think "reliable transmission shop" is an oxymoron, but really the truck is here at my shop and I have no way to get it to a trans shop. I always like to do things myself anyways so a few days figuring something out is a lesson learned, be it good or bad.
Hi Crosley, thanks for making a new thread. Guess I could have been more specific, let me start over.
My neighbor has a 94 GMC 1500 with a 4.3l w 4l60e auto. The engine has a rod knocking and he said the trans was stuck in low. I test drove it around the shop and he was right, but so was the price. I put a deposit on the truck because I have a fresh 5.7 tbi and 4l60e auto from a 95 GMC Yukon that I thought would go right in. I ran out to the salvage yard and pulled a 5.7 auto engine/trans harness from a 94 and installed it on the 95 eng/trans and realized the 94 harness was missing the plugs that plug into the connectors on the shift mechanism on the 95 trans. Then I went and looked at the oem trans on the 94 truck and noticed it has a rod linkage instead of the cable like the 95. I then learned that the trans from the 95 has a pulse width lockup controlled by the computer and the 94 wire harness will not work with that trans.
So back to google I go, searching for how to repair the 94 trans or make the 95 trans work in the 94 truck, that brings me to here. I read here how to make the tbi trans(im assuming thats my 95 trans) work in a carb'd truck. Now I don't know what will be the best route to get this truck on the road, cost being a major determining factor.
I have rebuild guides on the 4l60e and though I have never rebuilt one, feel confident I could pull it off. I know a trans kit is about $150-$200 but will that fix the stuck in low trans or will it need additional parts?
I have extensive knowledge in 12v systems and have dissected many wire harnesses so I even considered swapping the 94 truck dash/ign/eng wiring to 95 so it will be plug and play. About the same $150-$200 in dash/wiring to convert the truck to 95. Plus I would need to change the through firewall ignition harness hole requiring cutting/welding.
Could I piggyback the ecm's somehow so that the 94 harness stays intact running the engine and the 95 ecm runs the trans?
I should have the keys this weekend, I can then find out for sure about the speedo and manual shifting. If anyone knows some tests I can perform myself to diagnose this, OR if anyone has info on how to make the 95 trans work, please let me know.
Thanks for your time.
ok, i removed the 4.3l engine, 4l60e transmission, engine harness and ECM from the 94 gmc and installed a 5.7l from a running vehicle along with its harness and ECM. i found an exact replacement 4l60e in the salvage yard, they both even have goodwrench remanufactured stickers on them.
the truck is running smooth but this transmission does the exact same thing. only first and reverse, no shifting. i can put it in OD and take off, engine revs up to redline and im traveling about 15-20 mph? i let off the gas and it the rpms drop low but im still coasting fast, instead of slowing down relative to the rpms.
i can goose it while coasting and it will take off again but high rpms and no shift.
it does the same thing in 1,2,3 as it does in OD. low and reverse work seemingly fine.
any home diagnosis i can do, its apparently a common issue with these goodwrench trans...
from here, you need to find out if the shift solenoids are getting command to shift, you already have power going to the trans because if you didnt, it would have 3rd gear starts, and only have manual 2nd other than that.
from what your describing, a code scan is in order. if you have a decent scan tool with a live data stream, that could help you find what the computer is doing.
i will say it is rather odd to change all this stuff out including the pcm and still have the same symptom.
one thing i noticed, the speedo is not working. after reading a 4l60 troubleshooting guide, it mentions the vss being a cause of no upshifts. im double checking wiring now.
i just want to thank all you guys that took your valuable time to help me out. i know im not a regular here and you dont know me from jack but you still took time to read my issues and offer advice. i thank you!
after a few trips to the salvage yard, i finally have a working work truck with a freshened up '95 350 and od transmission that actually shifts!! all my oem gages work, ac blowin and everything so i installed my old flowmaster and duals too!
i painted my engine during rebuild but since the trans came paint marker'd from a salvage yard with a 30 day warranty, unfortunately i could not paint it.
engine in my living room after painting for reassembly
here i have my engine driven air compressor mounted but i have not installed it in the truck yet.
here is the truck its goin in and thats the 4.3 ready to get snatched
pics of the install tomorow, im exhausted.
thank you again guys!
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