goofy4wheelerkid

Let me preface this post by saying that I am a domestic full size truck fan. I've got 4 fords and 3 Chevy's, all 80-90 models, and can fix them with my eyes closed, usually. However, I know nothing about yotas except when they are working right, they do not get stuck, can snatch anything out, and run forever. My brother finally talked me into getting one (so he could stop pulling my Ford out and, well,

I bought a 1990 pickup with a v6, auto trans, and a million problems. Long story short, four wheel drive will not engage. I have
-bypassed the ADD system
-replaced the destroyed CV axles
-checked the tcase linkage
And after all of that, the thing is still acting up. With it on the ground, hubs locked in, tcase in 4lo (also did this in 4hi) the front driveshaft can be spun either direction by hand. The CVs do not spin. In 4lo driving, I have low gearing to the rear end, but no action up front. I intentionally got the truck stuck today, put it in 4lo and had my brother watch the driveshaft. He said it spins really fast for a few seconds and then stops. Power stays constant in the rear. Bad tcase? Broken chain? Please, any thoughts are appreciated. I'm at wits end with this thing.

Thanks
Goofy

scope103

If you can turn the front driveshaft by hand, then it's not connected to your "bypassed" front differential, and it's not connected at the transfer case.

Broken chain in the transfer case would cause the disconnect in the transfer case.

IF the ADD were working, then the front driveshaft can be turned by hand with the transfer case in 2hi . There are a handful of ways that the ADD can fail to engage, but NONE of them apply if the ADD is successfully bypassed. One possible place to start is by un-doing whatever you did to bypass the ADD.

goofy4wheelerkid

I should clarify, the add has been "bypassed" by removing the solenoid thing from the front diff and sliding the fork over the ensure they were locked together. With both front wheels off the ground and the hubs locked, I can turn the shaft by hand and turn the wheels.

Does anyone have a step by step of getting the tcase opened up to take a look? I can't find anything on the internet, and I have a Haynes book, which is great if you need oil changing tips or info on how to put a spark plug in, but that's about it...

Shady Cadence

Look for the factory service manual here on the forum, I believe it's downloadable. Search bar.

scope103

The manual you want, of course, depends on the transfer case you have. It should be listed on the door pillar (RF1A, etc.). Some transmissions (A340H, e.g.) have a "matched" transfer case.

goofy4wheelerkid

just to update, the linkage where it runs into the cab was broken somehow. I checked the linkage to the tcase by crawling under and moving it by hand, which it did. never occurred to me that maybe it was just not connected. Always the little things that defeat me.