Truck will only shift when in either 4HI or 4LO

[BudgetB3000]

Recently just began encountering this problem with my truck. I've been using 4HI and 4LO quite a bit as it is winter and snowing daily. As of this morning, my truck will only shift into gears if I first engage the truck into either 4HI or 4LO. What gives? This seems like an extremely unusual problem. The car will shift gears once I switch it back out of 4x4, but in order to get into any gears I must put the truck into 4HI or 4LO first. Anyone have any ideas as to why this could be? My truck is a 1998 Mazda B3000 5 Speed 4x4 3.0.

 

[RonD]

Not quite following

Assuming Electric shift 4WD with manual trans?

So if you select 2WD on the switch the 4High light goes out
Then you put transmission in 1st and let out the clutch, and you are in Neutral, no forward motion?

If you select 4high on the switch, 4high light comes on, and when you put trans in 1st it works normally?

Did someone steal your rear driver shaft, lol

 

[BudgetB3000]

Not quite following

Assuming Electric shift 4WD with manual trans?

So if you select 2WD on the switch the 4High light goes out
Then you put transmission in 1st and let out the clutch, and you are in Neutral, no forward motion?

If you select 4high on the switch, 4high light comes on, and when you put trans in 1st it works normally?

Did someone steal your rear driver shaft, lol

Sorry for the confusion. The truck does have an electric shift motor BW 1354. The truck runs an drives just fine in all gears. The problem that arose today is getting the truck into gear. When I start the truck in 2WD with the clutch in and 1st gear engaged I can drive and cycle through all the gears. The problem arises when the truck comes to a complete stop. Once the truck is stopped completely the only way that I can put the truck into any gear with the clutch depressed is to first switch the truck into either 4HI or 4LO. Once the truck is moving again I can switch it out of 4HI/4LO and continue driving in 2WD until the truck comes to a stop again.

 

[BudgetB3000]

I also just replaced the clutch, master and slave cylinder, pilot bearing, and all other related parts and the car has been running flawlessly for 1k miles so I’m at a loss .

 

[RonD]

Reads like air in the clutch system

Check reservoir for fluid level change

What I am assuming is that when you are in Neutral and stopped the clutch disc is not being released fully when clutch pedal is down all the way, transmissions output shaft is spinning at 0 RPMs when you are stopped
Clutch disc in Neutral is spinning at engine RPMs, say 700 RPMs
To put transmission into 1st(or any gear) the clutch disc must be slowed down to 0 RPMs, so input shaft matches output shaft RPMs

If slave has any air in it then clutch disc will rub on flywheel and pressure plate so can't slow down to 0 RPMs

Instead of switching to 4high, turn engine off and then see if it goes into 1st and then restart engine
Or don't shift to Neutral at stops, hold clutch pedal down and see if that works and doesn't require you to shift to 4high
Either of these working would confirm air in the clutch system


There is no mechanical reason for transfer case position to effect transmission, so air is most likely issue

EDIT
Well thats not exactly true
Transfer case has an electric clutch that is activated when you shift to 4high, so.................it would allow transmissions output shaft to spin to match rubbing clutch disc, so you could put trans in gear.
But bottom line..........you have air in the cl;utch system

 

[BudgetB3000]

Hmmm not sure how I'm letting in in the system but I guess I have a new problem to sort out. Thanks for the input RonD

 

[RonD]

Could be Master seal(top) or Connection, or Slave

Check reservoir, if level is lower then you have a leak and it will suck in air when you lift foot off the clutch pedal, doesn't take much air so fluid leak wouldn't be obvious at all, i.e. no drips on the ground