1993 Blazer will only back up in 4 wheel drive low. Why?

 

No forward in 4LO? No reverse in 4HI or 2HI? Or when in 4LO it ONLY goes in reverse? Big difference

 

93 blazer k1500 4x4. In two wheel drive, after putting the gear shift in reverse, it will barley back up, however, it will back, slowly as long as on a level surface. All forward gear work fine. When you engage the 4 wheel drive, reverse works just fine in 4-lo. In 4-hi, or 2, it will not reverse.

Before the problem, for a month before, every time I put it in Park, I would need to turn the key off before Park would hold. The day I put it in reverse and found it would only back slowly, the Park started working properly. I have always been able to put it in 4-wheel drive from neutral. Now it will only engage in reverse and to get it out of 4-wheel drive I must turn off engine because the engine RPM's will not drop down low enough as it has always done.

 

93 blazer k1500 4x4. In two wheel drive, after putting the gear shift in reverse, it will barley back up, however, it will back, slowly as long as on a level surface. All forward gear work fine. When you engage the 4 wheel drive, reverse works just fine in 4-lo. In 4-hi, or 2, it will not reverse.

Before the problem, for a month before, every time I put it in Park, I would need to turn the key off before Park would hold. The day I put it in reverse and found it would only back slowly, the Park started working properly. I have always been able to put it in 4-wheel drive from neutral. Now it will only engage in reverse and to get it out of 4-wheel drive I must turn off engine because the engine RPM's will not drop down low enough as it has always done.

 

4LO gear ratio is much lower than 2HI & 4HI, especially noticeable when in reverse, due to the gear ratio being even lower than any of the forward gears. Sure sounds to me like the transmission is slipping, and the lower gear ratio is the only thing helping you. Better have a transmission shop take a look at it.

 

I have checked with transmission experts and they, all three have said that the 93 transmission in the blazer it totally electric, meaning no bands, only gears. They feel the Sun hub is not broke because it backs up. Therefore, they feel it is electronic and it is in the transfer case. Maybe the TCCM. Captain Hook I am at a lost.

 

The transfer case is all mechanical: shafts, gears, and a chain. Impossible to only work in one direction. I would suspect a problem with the input drum assembly in the transmission. Do a Google search for "4L60E no forward gears", probably come up with something.

 

Thank you for your help. I have taken the Blazer to several shops and wouldn't you know... All said they do not think the problem is in the tranny, however, the all recommended I let them rebuild the tranny and should the problem still exists, it is most likely in the transfer case. I would need to take it to a 4-wheel drive expert. I talked to a 4 wheel expert and it was suggested I change an Actuator switch in the transfer case since I can put, from neutral, put it into 4hi-4lo and 2hi, however, when it is in 4lo, to get it back into 2hi, I need to turn key off do that do to all the grinding. I will run a check on the Actuator. The only info I got on reverse was it is thought the Actuator is bad and not letting reverse engage all the way in two 2hi. What do I know, All input is good. Again, thanks for all your good ideas, you might be right and I will rebuild the entire drive train. Your new friend, Cash.