sheriffav8r

My 4WD light wasn't working so I have been troubleshooting it. The light itself works, the sensor works, and I just replaced the vacuum motor (1AAuto $100), which now can turn on the 4WD light when I put vacuum on the vacuum motor manually.

My question is this: There are 4 lines on the transfer case vacuum switch. The green one seems to be vented to the transmission and has a valve like end on it in the engine bay (is it a one-way check valve????). The white one has continuous suction on it when the motor is running. The black one engages the 4WD fork and the red one disengages it. Should the red one have suction always on it when the truck is running to keep the fork disengaged? I get no suction from the red or the black no matter what position the transfer case is in so I'm just trying to figure out what lines should always have suction.

I ordered a "4WD vacuum switch" from 1AAuto and got a small vacuum switch with only 3 outlets on it. Any idea where I can get the big transfer case switch since that seems to be my problem? I need the 1 1/16" diameter one.

Cougsfan

I think that either the red or the black (one or the other) should have suction on them at all times. If it doesn't it is probably either a broken or plugged vacuum line, bad switch or bad rubber connector plug. The whole vacuum 4wd actuation system on Dodge trucks sucks (in more ways than one). I have replaced mine with a manual engagement linkage (Posilok) after I got tired of troubleshooting the vacuum system, and have been quite happy since.

carl48

i also like the posilok, geno's garage has a kit if you want to keep the vacuum motor , just run the suction line to it and disconnect all lines to the transfer case with either one you will really like your new 2wd low reverse

sheriffav8r

Does anybody know about Bob Verhoeff's 2WD low kit? Sounds like a manual vacuum actuator, but I can't find any more info on it....

On another note, can I just plug the txfr case switch and run solenoids off the white vacuum line to manually control the vacuum motor? I am thinking of 2 separate 12V solenoids teeing off the white vac hose controlled by a 12V Bosch relay. When the cab switch is off the solenoid to the red (2WD) vac line is getting suction. When the switch is on the red-line solenoid is de-powered and the black-line solenoid is powered. Does this hurt the transfer case? Then I will get a 2-Low and in effect, have a manually controlled front axle....

carl48

that is what is in the kit from geno's it would take four seperate solinoids two normally open and two normally closed to do it the kit has all four using one coil , compact with all pieces i just connect it up different than the directions to eleminate all of the vacuum lines and switch on the transfer case

sheriffav8r

I'm going to try a solenoid from Grainger. It is a 2-way, 4-position switch. It will remove my transfer case from the picture altogether. It is part number 6JJ43 and runs $41. I can run it straight from my main vacuum line down close to the front axle. Vacuum should be present only inches from the motor so engagement/disengagement will be quicker than stock.
This switch will run vacuum to the red/2WD side of the vacuum motor when the power is off while venting the black/4WD side. When I hit a push button lighted on/off switch it will then run vacuum to the black/4WD side while venting the red/2WD side. This way I can get the "2 LO" effect if I need it and basically have manually activated front axle engagement.
I plan on taking the vacuum off the stub next to the white line on the firewall. All told, this should cost me about $50-60 depending on the switch. I'm planning on mounting the switch on the transfer case shifter stalk so I can hit it when I need it. We'll see how it goes....

01RAMer

Using a 4-way, 4-port, 2-position with spring return and 12 VDC solenoid allows you to install the unit inline and forget it. Two lines go in and two lines come out. When switched off, the two lines basically go straight through. When switched on, the lines reverse dropping the 4wd setting 2wd. Easy to install and works anytime.
Cost was 43.84 from Numatics (AIROIL), P/N: L01SA459B000060. Might want to consider this.

Stamey

I got a new rubber grommet for the vacuum lines on my 96. This is the 4-hole rubber plug that goes on the switch. I found, when testing, that the rubber was fatigued and vacuum was escaping around the rubber. The actual switch was fine. I found this by squeezing the rubber grommet different ways while applying vacuum, and I heard the vacuum motor on the axle move, so I knew I had found the leak.
I wiggled the 4 lines out of the old one (plastic nipples connect the rubber lines to the grommet) and plugged them into the new one and it works great again.

Chris

sheriffav8r

I put the Grainger solenoid on with a Radio Shack covered lighted toggle near the transfer case shift lever. Now my front axle locks when I throw the switch and I have 2WD Low to boot. All for about $50. Works like a charm....