Gene

Certainly do what Don (hornbrod) says above. He's right about 99% of the time. But I can't understand why removing the system would have caused problems. If wires were improperly spliced together, that would've been done years ago when the system was installed. So I don't understand why problems would start upon removal. Much stranger things have happened.. Let us know how it goes. Gene

Understand completely your belief that it's related, if things were fine before hand, and messed up afterward, that makes sense. However, I can't for the life of me imagine how only disconnecting something could cause this. Is there any chance that any of the wires you disconnected could be shorting against each other? Could you have done anything that would have affected the turn signal switch, even bumping it, during the process? Good luck! Gene

Hi Tylerzap, This is a weird one. As DTA indicated above, bad grounds can cause all kinds of mischief. Typically, though, if it's a ground problem feeding back, the lights will not burn at full intensity, they will be dim. Also, are the front turn signals lighting up as well? I think you indicated they were. This would make ground issue less likely. One by one, pull each of the turn signal bulbs, and see if that resolves the issue. There have been cases where one filament of the dual filament bulb will sag onto the other filament, and this will let current feedback into the other circuits. Also, someone on these forums, several months ago, put a single contact bulb in where a dual filament bulb should have been, this shorted across both contacts in the socket and caused feedback. If you've checked each and every bulb, the only other area I could think of would be in the turn signal switch itself. The brake light switch feeds into this switch, if this switch had failed internally it might direct that current to all of the bulbs. But certainly check grounds, especially if lights light up dimly, and pull all the bulbs. Good luck! Gene

Hi everyone, I think you have to be a little careful doing this... I believe a fusible link is very "slow-blow" so a similar fuse (same amperage) will blow much more quickly. In other words, a 40 amp fuse run at 50 amps will blow fairly quickly. A 40 amp fusible link will take quite a bit longer to burn up. So be prepared to replace more fuses than fusible links! Gene

Hi everyone, Thanks for all the replies. I actually have been watching eBay. The problem there, of course, is twofold. First, you can tie quite a bit of money up in ordering parts. Second, I suspect that whatever I order to have on reserve I won't need, and the things I don't order, I will need. Of course, I suspect guys like Don, Cruiser, and Eagle probably have enough spare parts to assemble three MJ's out in their shed or garage… In thinking about aftermarket, I think FelPro quality is still good. That seems to be one of the few older companies that has not sold out in terms of their quality. Has anyone had experience with any of the online Chrysler dealers? Thanks. Gene

Hi everyone, The issue of replacement parts quality has been kicked around in several threads, and I think there are two parts to this. The first is whether there are any quality aftermarket parts at all. It seems to me that, over the last 10 years, the quality of aftermarket parts has deteriorated greatly. Moog used to be a good name, the stuff I've gotten from them recently has been junk. Timken bearings used to be the standard, I'm not sure that they are anymore. Several members seem to like Napa, I really have not been impressed with the parts I've gotten from them recently. It actually seems like AC Delco might have the best aftermarket quality right now. I've also gotten a few Mevotech suspension parts, I thought that they would be total junk, but they actually seem to be pretty good quality. Anyone satisfied with any brand of aftermarket parts? Secondly, I don't recall this being addressed. Where do you get factory parts? Our local dealership is very very expensive. The parts department is only open during business hours, and it is hard for me to get there. Has anyone found any of the online Chrysler dealers to be better? The other alternative, eBay, seems very very hit and miss for genuine factory parts. Thanks in advance for the accumulated wisdom of this group. Gene

Hi cruiser, I would be very interested in seeing this! Thanks Gene

Hi Don, Thanks for the link. Great writeup! I especially liked step 19! Hi desbennett, Thanks for your experience. Gene

Hi everyone, I've done a lot to my Comanche over the years, but I've never touched the fuel injectors. I've ordered a set of 746s. I'm wondering if there are any tips for replacing these. It looks like there are four bolts securing the fuel rail to the intake manifold. Then the fuel line and return line look like they have a plastic clip, squeeze with a pair of pliers and remove? Then each of the injectors has the electrical connector. I've been warned to be careful with these as they can easily break. My main question involves what comes next. Do you pull the fuel rail and all the injectors together? Or do you disconnect the injectors at the rail, just pull the rail, and remove the injectors individually? Finally, I've also been warned that the O-rings can become very very hard with age, and removal can actually be quite a bear. Advice from the collective wisdom of the group will be greatly appreciated. Thanks so much! Gene

All of the above is right on the nose. But here's another way that might be helpful to look at it… There would be three main causes for lack of heat. One would be the engine is not getting hot enough, the second would be that the heater core is blocked or not receiving the hot coolant, the third would involve the position of the airflow door under the dash. If you run the vehicle for a while, and carefully touch the large hose coming over to the radiator, this should be hot. Too hot to hold, hot enough that you'll only touch it for a second. If the hose is not this hot, then thermostat would be a suspect. If the radiator hose is getting hot, then feel the heater hoses, and see if they feel as hot. Hot radiator hose, but cool heater hoses, would go along with clogged heater core. There's also a vacuum valve on the heater lines, this could have failed shut. Finally, underneath the dash, there is ducting, and and air door to determine how much of the inside air goes through the heater core. The door may have failed. It's operated by a vacuum switch, that could be having a problem too. Hope this helps! Gene

Hi, About a year ago I got this oil pan (88 4.0) https://www.rockauto.com/en/moreinfo.php?pk=877970&cc=1181584&jsn=2 from Rock Auto. Fits well and seems to be decent quality. Gene

How did you check it? Gene

Agree with the concern about coolant in the oil. However, repeated short trip cold-weather operation can do this as well. An oil analysis would be able to tell whether there is just water, or antifreeze as well, in the oil. I have used Blackstone Labs www.blackstone-labs.com in the past. Gene

Dead battery + trickle charge for a few hours= almost dead battery. A dead or defective battery will pull system voltages down. FULLY charge battery, see if it reads about 12.8 volts, then check the rest of the system Gene

Hi crusher, So when you pull the headlight switch all the way out, the headlights will come on. What happens when you pull the turn signal switch lever toward you? Do the low beams come on? Do the high beams stay on? Or do the headlights go out? Gene

Hi everyone, First, I would like to thank Eagle for his very patient discussion above. I think I now understand the MJ rear braking system much better than I had. Second, who has real world experience with this? Anyone eliminate the height sensing valve and just run the brake line directly? Anyone actually running an XJ proportioning valve? If so, any problems with rear wheels locking with an unloaded bed? Thanks Gene

Hi fire797, Confusing is probably a charitable word… Here's my understanding of the situation. With an XJ, the weight distribution, front to back, is essentially constant. It might vary a little, but most of the weight in the back is the weight of the vehicle itself. In an MJ, the distribution of weight, front to rear, can change dramatically. It's a very light vehicle in back without a load, with a full load it becomes much heavier. Ideally, the distribution of braking effort, front to back, should be based on the weight in the front of the vehicle, and the weight in the back of the vehicle. So an XJ can have a fixed proportioning valve, since the weights will not change that much. If an MJ used a fixed valve, it could be set for the unloaded weight, in which case the back would not get the braking that it needs when it's loaded. Or it could be set for a fully loaded rear, in which case the rear brakes would lock up prematurely when not carrying a load. That's the purpose of the height sensing valve in the back, to judge the weight in the back, and to adjust the amount of braking that goes to the back brakes accordingly. But, the problem is, if you lose your front brakes, you want to have absolutely full braking effort going to the rear. That's why the bypass line exists. My system is stock. I have overload springs on the rear, which give it a pretty good lift, so I think I'm basically just stopping on my front brakes, with very little contribution from the rear. I'm actually thinking of eliminating the rear height sensing valve, and putting an adjustable proportioning valve in its place. I would then adjust this to get good braking with the rear unloaded. I rarely carry heavy loads, so this would not be a big deal for me. If I understand your post, and you're just running a line from front to back, I think you'll be having premature lockup of rear brakes when you're not carrying a load. Hope this helps! Gene

Ummmmm.... I do not think that procedure is complete. It will bleed the rear circuit that goes through the height sensing valve. It will NOT bleed the rear bypass "emergency" line. Gene

Good work! Gene

http://comancheclub.com/topic/40428-brake-bleeding/?p=407703 might be the link you referenced. I did not find it necessary to disconnect the link to the height valve. But perhaps things would have been quicker if I did! Gene

Hi Robbie, First thing, before even bleeding the brakes, is to be sure the back brakes are adjusted properly. Self adjusters don't always work. With the parking brake off, there should be very slight drag when you spin the wheel. Improperly adjusted brakes, which may be from a stuck or otherwise not working self adjuster, will certainly cause a low pedal. Here's how you think of bleeding the rear brakes. There are two sets of lines that go to the rear. One, for normal use, goes from the master cylinder, to the proportioning valve under the master cylinder, to the height sensing valve on the rear axle, to the wheel cylinders. When you do a standard brake bleeding, you are bleeding this line. But there's another line that goes to the back. This is the line that bypasses the rear height sensing valve, so that rear brakes will get full braking. This one is used only when there is a failure of the front brake hydraulic system. To bleed that, it has to be activated. And to activate it, there has to be a "failure" in the front brakes hydraulics. So, after finishing the regular bleeding, open one of the front brake bleeder screws, put a rubber or plastic hose on it and put it in the container of brake fluid to try to keep air from getting sucked back in. Now, with the front bleeder valve open, go back and re-bleed the rear brakes. You are now bleeding the second, emergency circuit, that bypasses the height sensing valve. When you're through with this, you then have to bleed the fronts again. And then, probably, bleed the backs again the traditional way. I'm not sure whether the above is the official factory procedure, or if it's what Pete references. This is what works for me. Finally, after this, the brake warning light may be on, because it has sensed the front hydraulic system failure. Usually, stomping hard on the brake pedal several times is enough to equalize this. If not, you may have to rebleed one of the hydraulic systems, to get the plunger to return to center position. Good luck! Gene

Hi Robbie, I have never done this, but believe me, I've done more than my share of stupid things. Don't beat up on yourself for this. Learn from it. I guarantee you, you will never make this specific mistake again! And, remember, you were the one that ultimately solved this. Gene

Hi Robbie, I think you nailed it this time! Look in the socket. If there are two brass contacts, they'll just be little round pieces of metal, then that does use a dual filament bulb, which would be 2057. One filament is the taillight filament. The second filament is brake/turn signal. If you put a single filament bulb in, it would only have one electrical contact in the middle of the base. If this shorted between both of the brass contacts, it could cause all sorts of feedback problems. So (by my memory, I don't have my vehicle here) the top two bulbs should be dual filament 2057 bulbs. And, yes, you were right all along, putting the wrong bulb in could have caused all your symptoms. I've never run into this before, but it makes sense! Gene

Hi Robbie, This really, really sounds like it's a ground issue. Usually when another circuit lights up dimly, it's because the ground of the original circuit is inadequate. I have a link in my signature for a wiring diagram, provided by another member. On page 12 of this is the ground distribution. According to this, there is a separate ground wire from -each left-hand stop/turn lamp -both license lamps -combined right-hand stop/turn lamps -the fuel pump. These all are joined together, and connect to one wire which is the one you checked where it screws into the body. Basically, when there is a bad ground, the current that has gone through the bulb and tries to return to the ground, cannot. So it goes into another ground wire, flows "backward" into that, into the right side bulbs, and eventually completes the circuit this way. I'm not sure just where it is, but there should be a splice point where six ground wires come together, and connect to the one wire, which is connected to the body behind the left tail light. If you are sure that the connection under the screw is clean, and that paint and rust has been scraped off to get a good metal to metal connection, I would try to find that splice point and see whether that may be failing. Good luck! Gene

So remove the bulb in question, just leave it out, and check 4 ways, brake lights, and turn signals. Do they work normally? Gene