AZJeff

I don't know for sure what year the original buttons came from (either 2000 or 2001). The replacement buttons I put in came from a 2000, and changed nothing about the behavior. The PCM came from a 2001, but has been refurbished by an independent shop in the past, so I assume it was from a 2001 originally. Here are the exact behaviors: · When the switch on the steering column is pressed to turn the cruise control “on”, the light on the instrument panel saying “cruise” comes on. · However, as soon as any controls are touched (including brake or accelerator), the cruise light goes out, and of course, there is no cruise control function. I have used the FSM to chase down the cruise control system wiring. Here is what I have done so far: 1. checked all wiring between PCM and servo. Checked all wiring between PCM and buttons on steering wheel. Checked all wiring to brake light switch. 2. replaced servo with new Mopar unit 3. replaced clockspring (due to horn issues, but it also feeds cruise signals down column) with new Mopar unit. 4. replaced switches in steering column (used, but checked out the same as old ones with ohm-meter) 5. sent PCM back to original repair shop, who reports "no trouble found" What's next?

As my sig. line shows, my MJ actually has a 2001 XJ engine control system in it. I have been struggling to figure out why the cruise control does not work, and have been chasing wiring and replacing parts with no sucess. I need the help of an "jedi master" on the cruise control systems used in the later XJ vehicles. Can anyone recommend someone either here, or on one of the XJ forums, that I can talk to and pick his/her brain about how to diagnose my issue correctly?

About 3 gallons of crazy glue should hold it down.

Dielectric grease also has another function, one that is common to many low-current or low voltage connections: it prevents "fretting corrosion". This type of corrosion can happen on almost any connector that does not have silver or gold or platinum plating on the contact points (fat chance of that on most auto connectors.) The grease seals out oxygen at the interface point between the two contact surfaces (at the almost microscopic level) and prevents increase in impedance (resistance) across the joint over time. Lots of different greases will work, as long as they do NOT have any metallic components in them (like molybdenum, lithium, or such). Silicone greases are the most common dielectric type, but polyethylene greases work well, too.

How does one use a bubble angle finder to determine caster? I know the principle of caster, and how it is set, but I don't see how you can attach a level to anything that is parallel to the centerlines of the two balljoint studs to measure the angle. Can you explain, please?

My bad. I misunderstood. How clean and smooth is the bore of the MC where the reservoir is inserted? I ask because if you used new o-rings when you got the new reservoir, the only other possible source of leakage would be a corroded bore....

Fluid leaking between the MC and the booster means a leaky, defective master cylinder. Replace it.

I will affirm Eagle's thoughts. Ground temperatures down 10 feet are going to be 60 degrees, even here in AZ. If the gas station tank has not been refilled recently, that is the temperature of the fuel you put into your tank when you refueled. Now let that gas sit in a tank in 110 degree air, and where the pavement under the truck is probably 140 degrees. That fuel is going to heat up a bunch, probably close to air temperature. And it will expand--a LOT. Fix your vent lines, and all should be normal again.

The small hole in the thermostat is supposed to help with "burping" the system to remove air upon refilling. It DOES help. Since only OEM thermostats have those, I always add two holes to my replacement thermostats before installing. I drill a 1/16" hole 180 degrees apart on the flange, and then install the thermostat with one of the holes at the "12 o'clock" position.

I just went thru this issue. To avoid spring rubbing, three things have to be set correctly: 1. The axle must be centered under the chassis by adjusting the track bar so that distance from the outside of the wheel to the outer edge of fender flare is equal on both sides. On a lifted MJ/XJ, this will require an adjustable track bar. 2. The axle spring seat must be centered under the spring seat on the chassis. On a lifted vehicle, this usually means extended control arms are needed if the lift is over about 2 inches. 3. The axle spring seat must be PARALLEL to the one on the chassis. This keeps the front spring from bowing in a manner that will cause it to hit the track bar bracket on the chassis. The only way to control this parallelism is with adjustable control arms. (This will also control your caster angle as well.) It sounds like you have tried to control all of the above, but the one variable that seems unknown is if the springs are really intended for an MJ/XJ. If their OD is too large, no amount of adjustment will compensate.

Do you have the wiring diagrams for both an 89 MJ and a 2000 XJ? That’s the first thing I would get before even STARTING the conversion. This is NOT a plug and play upgrade.

Agreed. Try this to confirm: Start the engine, and while it's still stationary, run the throttle up to about 2000 rpm for about 10 seconds, and then idle back down. Then put it in gear and drive away. If the problem is gone (or substantially reduced) it's your fuel line that is filled with percolated fuel due to heat soak. Fixing heat soak requires shielding/insulating the fuel line in the vulnerable areas (near the exhaust)

These are VERY good points that I did a less eloquent job of describing. Making this kind of stuff isn't cheap or easy. Look at how much suppliers charge for the fender flares for an XJ/MJ, and the demand for that part is MUCH higher.

I am a retired mechanical engineer who worked with LOTS of plastic molded parts in my career, so here are my two cents: Owing to their size, the original parts were probably created by some short of sheet forming compound. This is a plastic sheet resin that is heated, and placed into a mold where it is pressed into shape and then allowed to cool. Sometimes the material has glass or mineral strands added to increase stiffness of the finished product. Making a duplicate of this part would, of course, involve first making a die (mold) that is essentially an inverse image of the part, both inside and out. Of course, the mold has to be "tweaked" so that the softened plastic does not pull too sharply in corners and whatnot, and thus tear, so an exact inverse image is not usually the shape of the final die. Believe it or not, in low volume production, this could actually be made from hardwood, like maple. Once a die is made, then a suitable material must be found. Sheet forming compounds in large sizes and thicknesses can become pretty expensive in low volumes. It might cost a couple of hundred dollars just for a sheet that is 6 feet long and "x" wide. Of course, the compound you choose also needs to be formable in the die you create, as the "stretchiness" of various resins are different. This might mean some trial and errror experimentation might be needed, and you might end up creating several unusable versions before the die is optimized. All of this, of course, would required a facility with a large oven to heat the resin sheet, and a the ability to fixture the mold halves and compress them together once the heated sheet is placed into the mold. Owing to all of this (cost of raw sheet material, cost of die development and fabrication), making a duplicate of the OEM part in low volumes would result in some pretty high piece part costs. This makes creating parts from fiberglass or carbon fiber MUCH more cost-effective. Making the part in fiberglass or carbon fiber would be done similarly to the way boat hulls are fabricated. A wooden mold is still needed, but it's only the inverse of the outside of the part is required, so the mold cost is lower. The actual part is them "laid up" by hand, with sheets of glass or carbon mat soaked in resin, and then applied to the mold (which has been coated in a mold release compound.) This method is tedious from a labor perspective, but does not involve a fancy facility with an oven and mold presses. It also is more fragile, as noted previously. All things considered, unless you are indepenently wealthy, the idea of "tooling up" to make a OEM equivalent to the original "spoiler" is pretty much problematic. Sorry to rain on the parade here.

So where does one get a spring to put into a hose if the old hose did not have one?

I have mixed opinions about those fancy type outboard seals. People who do a lot of driving in deep mud might find those type of outboard axle seals useful. There is, of course a possibility that mud can become trapped between the inner and outer seals if the mud is thin enough in consistency. (The inside of the axle tubes are not particularly smooth, and thus getting a good seal there is problematic) In other words, they may "fix" one issue, and possibly introduce another in its place. If you drive in dust/dirt like I do, the factory plastic seals are just fine, as they keep rocks out of the axle tubes. This is what the factory intended, in that big "chunks" don't get into the tube, yet minor water and dust gets in (and then gets back out). Regardless of the type of seal you choose, it doesn't mean you can submerge your axle housing with great regularity and for any length of time. The inboard seals are designed to keep oil IN, and don't do much to keep water OUT. YMMV.

That's cheap compared to the aftermarket one I bought from Rusty's ($129). The Rusty's part is OK, but certainly not 4X as good as the OEM one.

I have a CSF in my truck, and also used one in my last XJ.

As I said previously, a properly maintained 4.0 does NOT need an expensive, super-whammy Hesco water pump. It WILL provide a bit more flow, but if the vehicle is already overheating, it's NOT becuase of water pump flow, it's because of something else that is more significant. (OEM water pumps either flow or they don't, since the impeller is either corroded away or is not.) DO NOT remove the fan shroud. The fan shroud is NOT just a safety device to protect your fingers. It actually helps channel the air over the propeller blades to improve it's effectiveness. If the fan is rubbing on the shroud, it's because it's broken or installed wrong (or as you say, the motor mounts are bad.)

I got my 18lb cap on Rock Auto. Or you can buy a Mopar. Either way, it’s obvious the Jeep engineers realized the 4.0 was going to run hotter than the average engine, and bumped the cooling system pressure to delay possible coolant boiling issues. The 18 lb is needed in hot climates.

If an MJ is equipped with all the original type parts (OEM or equivalent), and they are all in LIKE NEW condition, there is no reason for a 4.0 to overheat in normal use, even with AC on, and even in places like where I live, Phoenix. Hood vents, dual electric fans, and other suggestions will make a BIT of improvement, but should NOT be needed to meet normal cooling needs. If an MJ/XJ 4.0 is consistently overheating, it is ALWAYS traceable to missing parts (fan or shroud) or worn parts (fan clutch, radiator, thermostat, etc.)

Water pumps are all the same, in terms of performance, except for some of those super expensive, fully machined ones. The only difference between a Mopar and some cheesy AutoZone pump will be in bearing life, NOT in pump flow.

A couple of things to note: 1. the thermostat should have the small vent holes in it to allow the system to "burp" properly on a 4.0 The Mopar brand ones have this, but you can take a quality aftermarket one and drill two 1/16" holes 180 degrees apart just inside the seating surface and create the same effect. (Be sure to orient the thermostat so the holes are at the "6" and "12" o'clock positions when it is installed. 2. the pressure cap for a 4.0 is an EIGHTEEN POUND cap from the factory. Everyone tries to sell you a 16 lb. cap, so beware. 3. The CSF three row (all-metal) radiator is about as good as you can get for the space available. The MJ/XJ cooling systems are sort of marginally designed. When all parts are 'in spec.' the system will cool under even the toughest climates in N. America. But, if one part of the system is not up to snuff, then all bets are off. The system does not tolerate parts that have deteriorated due to poor maintenance.

If you have no lighting at all, you basically have a battery that is not connected to the wiring of the vehicle. I am not as up on the older MJ type wiring, but since they seem to use fuseable links instead of the more modern power distribution block, I am leaning towards what others are saying--one or more fuseable links is blown or disconnected.

It's going to be SUPER low, like under ONE ohm. Any cable that is got enough resistance to prevent even the most basic electrical functions (like a dome light or parking lights) will measure VERY high impedance, in the tens of thousands of ohms.