Here's the deal. The first snow storm of the year has fallen, so on my way to to work I tried putting my Ram into 4hi. The stick on the floor seems to go, but 4hi will not lock in and the light 4wd light doesn't come on. 4lo works, but the dash light doesn't light up. When I try turning 4hi on while rolling down the road I do hear some sort of electrical hum, but dont here while sitting still. Anybody know whats up?

 

Your front axle isn't engaging. Check all the vacuum lines going to the CAD on the pass side of the axle.

When you say it goes into 4 low its really 2 low because like I said, the axle isn't engaging.

 

I agree, check the vac lines first.

That's one of the reasons I engage my 4x4 at least once every couple weeks all year 'round. Just to make sure everything's working when I really do need it.

 

check vacuum lines un front axle, if unplugged, this happens

 

Where in Maine are you? I am down in Wells. Had to drive up to work in Portland this morning. 95 was a mess.

 

yea check the cad housing, theres 2 lines, one black and one red, both go into a diafram on the side of the cad housing. shift it into 4H with the motor running, get under the truck and pull one of the lines off. you should hear the air rush out. if you dont here anything most likely its the vacume switch on top of the transfercase.

 

Hey guys I'm having a similar issue with my '98 extended cab ram. The light won't come on when I pull the lever back. I checked the red and black vaccum lines to the front axel and to the T-case and they appear to be ok, I did however find a pair of white and green vacuum lines that were burned off from the exhaust or something like that. I'm guessing these go to the switch on top of the transfer case? I was able to trace them to the top of the case but I can't be sure since its snowing like crazy and I was laying in the driveway. If these are vaccum lines to the T-case where do they connect to on the other side? I looked briefely but couldn't find the other end. Could this be the source of my malfunctioning 4wd? Thanks for the help!!

 

hey boys, iv got a 99 ram 1500 5.9 4x4 sport, iv got a similar problem, i throw it into 4HI and it feels like it goes, but the light doesent come on, put my foot to the floor and iv got traction but anything over like ten KM/H and it feels like my trucks gonna implode, its realy rough and vibrates alot and makes noise, not grinding noise but noise not the less, i threw a vac guage on the axle and t-case vac lines and i got like 30PSI so iv got no ideas, i was thinking hubs but arent they shifted through vacume? and if iv got the pressure..... im lost, plus no heat. peace JJ

 

zilla24: Do the lines look like this: https://dodgeforum.com/m_705405/tm.htm ?

justincredible5: Check your u-joints on the front driveshaft. The 4WD light not coming on could be completely unrelated to your vibration.

 

I'm pretty sure that was the line, there was a white one with it though and it was wrapped in a burnt foam cocoon. Where is that supposed to plug in? And am I right by thinking it connects to that vacuum switch on top of the T-case?