I have a 2001 1500 Ram mag v-8 (360) that the cruise control doesn't work- all of the dash lites come on as if it was working, it just doesn't "grab" and maybe related- the air in the cab(fresh and a/c goes off when the engine is under a load ie: when passing, going up hill ext. I read another post where a gentleman said he had a vacuum leak in a corroded line that runs under the battery that caused those 2 problems. I went out and checked and I don't have any vacuum lines running under my battery box. If a vacuum leak is in fact the problem could someone please tell me where and what lines I should run down? Like where the line should start and finish and a good testing method? I read 2 hours of posting this morning and this is my first post, I have yet to learn how to search this forum for related topics so if this has been addressed I'm sorry and please leave me a link to the answers. Thanks all
Dan

 

The cruise control module is behind the left headlight near the battery. I would start there it's a tough spot (thats where mine was leaking. Just cut the bad kinked piece out and there was enough slack the reconnect) and trace it back to the motor.

 

welcome to df. there is a search item up at the top of the screen, in red. you can put in keywords like 'cruise' and 'vacuum' and you can limit the search to a single forum like 'dodge ram 2nd gen'.
here's a collection of interesting pics. https://dodgeforum.com/m_735291/tm.htm

the vac line that goes to the cruise comes off the passenger side intake manifold. there are some t's. and some go towards firewall for heat/ac/etc and one comes toward front of the truck and across the top of the motor over AC compressor and PS and goes over to drivers side front corner, under the battery where there is some cruise stuff.

also do a search on ac controls check valve for an explanation about 1 or 2 check valves in the vac lines that near passenger side firewall. the front vents require vac to operate, when vac is low the door will close and change the air flow to the defroster.

here's a pic of the cruise vac line. dead center of the pic.

 

an old post from year 2000 that might be of interest:
----
I had ordered a replacement part from Dodge that is supposed to correct the
'Wild Vents' problem. This is where AC/Heat air blowing out vents
mysteriously changes and comes out other vents. It is most prone to happen
when accelerating. I read that the cruise control can suddenly 'pop out' of
setting too.

I haven't had the vents change wildly like that myself, but I have had the
'Defrost' setting refuse to work, then come on suddenly 10-15 minutes later.

Chrysler's 'Fix' is replacement part number 04677204.
I think there is a TSB on this.
I had seen the description of the problem in some automotive service
magazines.
My local Dodge dealer told me they now had the part, and I went and picked it
up (plus a broken passenger side sun visor clip). Cost was $7.84


The replacement part turns out to be about the size of a 35 mm Film can and is
a small vacuum reservoir with a built in check valve.
The original part (4306923) was a tiny check valve about the size of the tip
of my thumb. These check valves are in the vacuum line connected to the
nipple just rearward of where the PCV valve hose connects on the passenger
side of the engine. Just behind this check valve the vacuum line T's off that
goes to the cruise control mounted underneath the battery.

But when I went to put it on, I found that the new part lacked the proper
rubber hose fittings to install it. The new valve 4677204 has 3/16 nipples.
The new valve comes with only one rubber reducing elbow which has a female 3/8
end, and the other end 3/16 female.

The original check valve 4306923 has 1/4 plastic nipple ends and has a 1/4
rubber female elbow on one end, and short length of 1/4 rubber hose on the
other. The new valve's 3/8 rubber elbow is wrong - too big to seal to the 1/4
nipple at the intake manifold.

I went back to the Dodge parts counter to ask for the proper rubber fitting to
make it work, but they said they didn't have them and suggested I would have
to go to a parts store. At the local Advance Auto I could not find exactly
the right fittings, but was able to put the new check valve on using slightly
smaller fittings:

Motormite Mfg. Vacu-Tite! pn 47411 rubber elbow with 9/64 and 7/32 id ends,
and Motormite Vacu-Tite pn 47411 rubber straight with 9/64 and 5/32 id ends.

Seems sloppy on Chrysler's part - but maybe later model Rams than a 1995 have
different sized vacuum hoses and manifold fittings ?

 

what they said, but i also had a leak in my 4wd harness that runs to the transfer case from the vacuum harness on the engine. leaking portion was the rubber block that fits onto the vaccuum switch on the t-case. replaced the switch also as it was stickey, both from chrysler (switch can be had other places, harness not so much) was around $60. worth a shot. my line to my CC was also worn through on the ps pulley, although that may have been a mechanic misrouting the line (ok, it was me...)

 

Thank you all for such good information, not only about my truck but how to find stuff in the future. I went out this AM. and in less than 30 seconds found the bad vacuum line, it litterally fell apart in my hand and was a result of knowing where to look, thank you again. My Dodge dealer doesn't stock the replacement line so I guess I'll switch over to copper and 2 pieces of rubber. I can't say enough about the quality of the gearheads on this forum. Dan

 

One last simple question and I'll put this thread to bed. On the termial connections at the tee and at the cruise control module, the rubber boot that the vacuum line goes into, is that a simple push pull assembelly? Say at the tee by the manifold(see pic supplied by dhvaughn, thanks) do you just push the line in to install and pull to remove? If I pull the old bad line out do I have to replace the tee so the new line will seal? Both ends are hard enough to get to that I don't want to use the trial and error method. Any hints on hooking up the cruise controll end would be gratefully accecpted also, should I just pull the battery and box and then the cruise control mod so I can make up that end? I am so impressed with this forum that a newbie neophite can ask questions and get intelllegent replies without anyone calling him stupid. Please everyone who replied take my thanks in the spirit they were given.
Dan

 

yes they just push/pull. if they are dry and hard you might try some wd40 to loosen them up and prevent cracking. you were saying the dealer didn't have the small 1/8 lines in stock, but i'd think vac is vac and any standard size line and T's would work as long as you can rig/fit it to not leak. i've even stuck small lines inside bigger lines as 'adapters' - as long as it doesn't leak.

 

I could only find a 3' stick of the hard plastic vacuum line in town so I replaced the 3' from the cruise controll mod towards the engine with the aid of a coupling made of slightly larger rubber tubing and all is well, both the cruise and air work fine. Thanks again for all the very good info, without it, it would have been a trip to the dealer to get it fixed.

 

I was having the same dreaded problem with the phantom flapper, but to those of you who replaced the check vale, did you check it manually? (By that I mean sucking in or blowing to see if it effectively shut off the flow of air one way or another? The check valve closest to the firewall seemed to work just fine via that method, but the one closest to the manifold seemed to leak. I found this odd because the 4WD and cruise works perfectly (knock on wood), but my A/C flapper keeps flipping. Theroretically the second check valve (one closest to the firewall) should negate any vacuum.loss that escapes by the first one and the 2 accesories that should fail because they don't have their own independant secondary check valves are the two that in real life work. I went ahead and bought the upgraded version ( the dealer didn't realize you could put them on rams, he said they had been putting them on Caravans and Stratus as upgrades). I have yet to buy the adapter rubbers but I was just wondering what results ya'll came up with???