99 ram transmission issues. wont shift out of 1st while in 4 lo.

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

fastang87

Junior Member
Joined
Jan 28, 2017
Posts
3
Reaction score
0
Ram Year
99
Engine
5.2
been working on my old truck a while now.
swapped a 97 trans into this 99.
shifts in 2wd decent
wont shift out of 1st gear in 4 lo
speedometer works.
also the key trick does not work to read codes?? just shows mileage still.
so i have a sensor on the back of the trans and one on the rear diff. what do these 2 do differently??

to shift wouldnt the truck read the one in the trans since it has no clue if I am in 4 lo or a high gear?

Thanks in advance!
Chris
 

dudeman2009

Senior Member
Joined
Feb 9, 2016
Posts
1,562
Reaction score
208
Location
Arizona
Ram Year
2001 1500 Sport with enough electrical modifications to make my brain hurt
Engine
Magnum 360
Thats incorrect, you should have all gears minus overdrive in 4 lo (shouldn't be going 40mph in low range). All 4Low does is reduce the transmission output to the differentials from 1:1 to 2.72:1. That being said, in 4 low in first gear you'd max out at about 18mph, thats bouncing off the redline and guessing that you have the 3.55 rear end. If you have the 3.792 rear end you'd only be able to go about 16.5 ish.

Because 4 low is basically a 10:1 reduction for the transmission instead of the usual 3.55/3.92:1 reduction in 2wd or 4HI, you might not feel the shift as the slight jerk is lost in the reduction.

If you cant surpass 20mph, you might have an issue, but i'd start with a fluid and filter change first.
 
OP
OP
F

fastang87

Junior Member
Joined
Jan 28, 2017
Posts
3
Reaction score
0
Ram Year
99
Engine
5.2
Thanks Dudeman. I will check for those speeds asap. yes it is a 3.55 ratio truck. I ran it until 3000-3500 rpm and didnt feel a shift. will re check and do a fluid /filter change. it has been a while.

How picky are these trannys ? do they absolutely need atf +4?

Thanks again
Chris
 

dudeman2009

Senior Member
Joined
Feb 9, 2016
Posts
1,562
Reaction score
208
Location
Arizona
Ram Year
2001 1500 Sport with enough electrical modifications to make my brain hurt
Engine
Magnum 360
Some guys will tell you that regular ATF or even Dex/Merc is ok. I'd call that a big fat NO. ATF+4 is a must, anything else and you're asking for trouble, these transmissions are very picky.
 
OP
OP
F

fastang87

Junior Member
Joined
Jan 28, 2017
Posts
3
Reaction score
0
Ram Year
99
Engine
5.2
Thanks guys! I will drain and replace with atf+4.
 
Top