Need Help With 96 XJ

[liquidXJ]

Hey, new to this forum and I'm in need of some help with my 96 XJ 4.0 five speed. I bought it strictly for a work vehicle and maybe some fun when it's not being used for that. Anyways.... Ran and drove just fine for about a month or so. What I know about it... Engine has been rebuilt, 2" suspension lift, borla exhaust (no cat), aftermarket stereo, aftermarket temp gauge, additional fan for the radiator nothing serious. It was throwing a CEL so I went and got the codes ran, front O2 sensor. Since I ordered it online it took a little bit to come in, during this time I had the power steering looked at by a local shop because it was whining a bit. Found that one of the lines was routed too close to the fan and it was just a matter of time before it ate through it completely. Had the lines replaced and re-routed. Got it back no problems, no whining. While on the way back from work one day it started sputtering and actually stalled out on me pretty close to my house. Gas gauge read nothing and the light came on. figured it just got low on gas. Ran back to my house and put about 3 gallons in it. Still wouldn't start. Tow strapped it back to my house with my truck and figured it had something to do with the O2 sensor.

Next day I replaced the O2 sensor and it fired right up in the driveway. Ran for a good 2-3 minutes and then died. All this time the gas gauge light was still on and I'm thinking maybe its still low on gas but I couldn't get started again to get it to the gas station to fill the tank. After doing some research all my indicators pointed to the crankshaft position sensor. Went and picked up the sensor. When I pulled the old one out it looked like it was brand new and had just been replaced but I put the new one in anyways. Still cranking but won't turn over and the gas gauge light is still on. I pulled the door buzzer to see if I can hear the fuel pump energizing. Nothing. Replaced the fuel pump, strainer, filter and all the lines/clamps associated with that area. Nothing, still cranking won't turn over. Also I still can't hear the pump kick on. I've read some things about the ECM and it shorting out. I'm open to try anything at this point but not really sure where to start seeing as how it was running and driving less than a week ago. I've swapped around relays with no change in the problem as well.

Any and all ideas are welcome seeing as how I'm somewhat new to the jeep world.

 

[greg92jeepxj]

Hello and welcome to jeeps.com . Before buying any more parts , it's time to do some proper diagnostics . May I also add that over the counter parts like oxygen sensors , cam and crank position sensors , coolant temp and more are a headache that has plagued more jeep owners and probably auto owners too. So where are we supposed to buy our parts ? First , we want to buy known good brands . NGK is a known good brand for oxygen sensors ( wish I had a parts # for you.). Cam and crank sensors are best obtained from the dealer. I know , they're too expensive there. When you consider the agrivation caused , the constant parts swapping ( sometimes for the same part) and the $$ already laid out , it's worth the expense. I would suggest checking the fuel pump pressure and fuel,pressure regulator but you'll obviously have to confirm that the fuel pump is actually working. With the key on , check the resistor on the driver's side under the hood . It's a white square looking thing with two terminals and two wires to it. You'll need a volt meter or at least a 12 volt test light to confirm a reading. A proper check is with the wires disconnected and a ohms check but right now we need to know is voltage getting across it . A good check as well with a test light is the wiring harness connector under the jeep near the fuel tank near the fuel filter. You'll want to know that voltage is carrying there. It's ground should be part of the vehicles continuous ground system but a voltmeter will confirm that it's good by using the meters black lead on the ground and the meters red lead to the hot wire. The rest of the wires are the sending unit to,gas gauge which you can check later if fuel bauge is suspected faulty. There may be a ground bolted to the body which if corroded will give gas gauge errors. Under the hood , open the power distribution center where you were swapping relays . Look for power with the key on from terminal 30 on the fuel pump relay . If good , jump that to terminal 87 and listen for the fuel pump. If good , the problem is with terminal 86 & 85. Check for any fuses that may not be carrying voltage . The fuel pump relay gets power from a fuse but is tied in with the auto shutdown relay. You'll want to check the ASD relay as well as you did the fuel pump relay . DO NOT jump out this relay , just look for voltage . When checking relays , YOU SHOULD have a computer safe test light. Most relays feedback to the PCM ( power train control module ). That is a vehicles computer. You do not want to cause voltage spikes . A 12 volt test light across a computer feedback circuit will attempt to draw 12 when in fact the circuit is only supplying maximum 5 volts from the PCM. A computer safe test light can be used on any circuit up to I believe 28 volts but cannot be used on high amperage circuits like alternator or starter . The computer safe test light had a diode instead of a 12volt light bulb and the diode only consumes about a 1/4 of a volt. That's PCM safe ! Once it is established that current is good to the fuel pump , hoping your starting and running issues are over. But at least you'll have to confirm this before you move ahead. If you've still got a no start , then we'll go to check spark , injector harness connector volts and ground ( computer safe ! ) . Remember , the cam and crank sensors as you may know are what fires the injectors and coil(s) . Your '96 will have one coil but 2000 and newer have distributor less ignition systems ( DIS ). You can check for spark when diagnosing the fuel pump circuit with an in line spark tester . You can pick one up when you get the computer safe test light. If the counter person looks at you funny , Napa may be a better choice of parts stores. I hope . Before faulting the PCM ( not always the case but low on the probably list) , do these checks first . Obtain your results and please post what you've got . Hope this helps . Thank you for your membership here at jeepz.com .

 

[liquidXJ]

Thank you very much for all the diagnostic ideas and support! I will make sure to try these out and be careful as well! I'll be sure to post results and thanks again!

 

[greg92jeepxj]

Your most welcome . I stress the BE CAREFUL part so much since I once too got ahead of myself and committed a blunder which cost me a PCM. Besides , we should be practicing proper diagnostics if we want to really find the root cause. My biggest pet peeve is the auto,parts on the market today. Whenever we try to do right and follow through properly , we end up back to square one when we replace parts . We think we fixed it when we may have just added to the grief by installing inferior parts. Then the symptoms come back or something else appears . Not to bad mouth auto parts stores who are out there for us , but if there going to sell parts that are way down on the quality control list , then expect to be bad mouthed. Ok , this is a post on a thread for a request for help , not a rant column. But you see my point. We just hate when we fix it and end up chasing our tails .

 

[liquidXJ]

ok, went over things and then had some after thoughts as well.. Started with the volt meter and checked just about every wire I could that related to the ignition system and the fuel system. Then I just checked for shorting out wires, bad wires, and bad grounds in general. All of my tests indicate that there is power going to the fuel and ignition system when/where it should be. I tested the relays, checked all fuses in the power distribution center as well as under the dash. The only suspicious wire that I found was the fuel pump ground wire (located under the rear drivers side quarter panel). It appeared to just be a self tapping 8mm bolt right through the body, so i took it off, got out the grinder and took it down to the bare metal then re-attached it. Low and behold she actually started for about 5 seconds then died again. I also added 2 more gallons of gas to the tank after this starting incident. Add these 2 gallons to the initial 3 that I put in when I figured it may have just been low on gas and it should have plenty in there to start unless thats an incorrect assumption. It continues to crank and almost start at this point. I disconnected the CPS for a few seconds and then plugged that back in and tried again. Same thing almost starts but just won't. I'm starting to suspect the CPS again and would like to get my hands on a MOPAR one and spend the money for it. I've also considered junk yarding it as there is a sizable junk yard close by and has several Jeep Cherokees in it, a couple even in my same color which I have nipped many interior parts from since its a nice match.. I digress... My next question is does the CPS differ from a manual trans to an auto? If thats the case then junk yarding is out because none of the cherokees there are manuals. In which case whats a good site to get some OEM parts from or is it better to just go to the dealer at that point? Thanks again for all the troubleshooting tips, help, and suggestions! Also I cannot seem to locate the fuel pump resistor and I'm wondering if it was bypassed at some point and then taken out? Or am I looking for the wrong thing? Bahh! It's frustrating but fun at the same time! I'm determined to get this XJ back on the road!

 

[greg92jeepxj]

Thank you for the update . The ballast resistor could be on the firewall , along the fender well , or by the PDC . Incidentally , I believe there is also a relay outside the PDC called a ballast resistor relay. Just more parts in the equation for more diagnostics but equally important . The resistor should be white with two 12 gauge wires plugged into it but since I don't have a reference to a 1996 so I cannot confirm exactly. To my knowledge , the CPS for auto and manual are the same . They are mounted in the same location as well. Both a pain to get to. Glad you mentioned you've got a manual transmission , that brings up another thing to check. In addition to any other contaminants that may find their way to the CPS , debris from clutch wear will coat the sensor as brake dust coats the front rims . Go ahead and pull the CPS and inspect it. If it is debris covered , clean it off with some brake cleaner ( applied to a rag , don't spray directly) and reinstall. Try this to see if it will start and run. I've got the original CPS in my jeep and it still works . OEM parts are the best but for how long is anyone's guess. Hope this helps . Looking forward to your post and looking forward to success.

 

[liquidXJ]

Well I was poking around the coil and found this connector. It supplies power and ground directly to the coil. I removed the battery, disconnected the grounds associated with the area as well as the wires connected to the alternator coming off the same harness to make removing it easier and I was able to get the wiring up to a level where I can easily work on it. I would like to just take the pins out and cut into some fresh copper further down the line but k can figure out how to remove the pins to do so. If that's not an option then I was planning on heading to the junk yard in the morning and cutting out a connector and the wires and just soldering them together but if someone has a better suggestion I'm all ears.. Also I noticed that there is a nut missing on the bottom of that same connector on the alternator so I will grab one of those as well. I'll post the results tomorrow thanks again!

 

[greg92jeepxj]

Wow ! Those wires got pretty beat up ! A repair here is well worth the effort since it is likely that voltage leak and grounding most certainly will contribute and likely be the cause of ignition miss . On small terminals like these it is difficult to open the crimps and effectively reuse them so the best option is either to replace with the same terminals if they can be found easily and timely or just clip a replacement as you plan to. I like solder and heat shrink connections for security too. I go overboard on these connections just to be sure . I out liquid tape once the heat shrink cools in the event the heat shrink isn't good quality and fear the insulation isn't durable. You can hang on to the old connector for prosperity ( I do ) in the event that replacement terminals are found for a quick fix another time ( this jeep or another ). Would save the trip to the boneyard and hasten a repair. Since the wire has suffered damage in several places , it's definately a good idea to replace all the questionable length of wire to be sure of a solid repair. After all , your objective is to cure this no start and this is definately the right place to inspect and repair. Since the engine is almost starting and almost running , I'm as anxious as you to see what effect this repair will have on the problem. Your doing a fine job inspecting and found a viable possible cause . Good job. If you can put a heat sink in to the wiring while doing the solder job , that will help greatly to prevent heat traveling up the harness which possibly causes harm to sensitive components. The distance between the connector and the PCM where the voltage signal originates from will dilute the heat but we should never take chances . Since radio shack has closed its doors , I hope you can get something adequate for a heat sink if you need. But I do recommend using one to be safe. As far as the connector you mentioned on the alternator , I believe your talking about the field connector ? I think there are five nuts that hold it on . Three diode conmections and two mounts ? Well worth making a proper repair here . Again , good detective work. Inspection is key in every repair since we don't know what amount of harm is inflicted on our vehicles and must be on top of these items every time we pick up,the hood or climb under them. Looking forward to up coming posts and thanking you once again for your sharing with us as these kind of problems are valuable to diagnostics to everyone. Your determination is admirable and we know you'll succeed .

 

[greg92jeepxj]

BTW. , something worth mentioning is if here is intermittent conductivity in this connection and causes the no start , the ASD could and will go into mode which causes fuel pump to shut down . This is a feature that is incorporated into the electrical system . If any problems are detected , the PCM shuts down ignition to kill the engine to prevent damage. This of course means fuel system as well. Oil pressure , coolant temperature etc. are what triggers ASD . If there is a loss in amperage to the ignition , the ASD relay will feel the back feed and it's possible the energizing circuit of its relay will trigger a shut down either intermittently or set totally until the key is recycled. A no start drove me crazy once until I found poor connections due to broken harness clips on the ignition coil of a GM 4 cylinder which was similar in design as this ignition system is. After replacing an ignition module , there still was intermittent hesitation and a stall or two or even some rough starting . After fixing the connections , problem was solved . Hoping the repair will make substantial headway on this repair overall.

 

[liquidXJ]

well I soldered in the new (used) junkyard ignition control module harness that I nipped out of the same year XJ and still crank no start.. I picked up a brand spanking new crankshaft position sensor from the dealership as well which is about to be installed here in a few minutes. I won't lie though I am a little hesitant to install the sensor because when the chrysler dealer pulled my VIN there were several different CPS models and I stressed to them that it was a manual, 4.0 because I've heard conflicting reports on wither this makes a difference or not. They seemed a bit confused by the part request and it took a couple of guys in the parts department to figure out which one to order. Based on the fact that I have a no start problem and I feel like I've addressed all the other obvious signs if this doesn't work then I'm going to be even more suspicious of wither or not it's the right part. For a 100 bucks it had better be... Anyways I'm also going to have the battery load tested at this point since I've been cranking it a lot and it hasn't been charged. However I have been checking the voltage constantly on the battery throughout this whole process and it is also a damn near brand new Optima yellow top. I'll report back with my findings.

 

[liquidXJ]

oh also real quick.... found a 93 cherokee just up the road from my house (better body condition than mine), 150K miles, 4.0 auto, pretty bone stock. Guy is asking 1K for it, he states that it has a problem with the ignition circuit. In the fact that you have to bridge the starter solenoid and once it starts everything is fine... I'm assuming that he means bridging the relay at the PDC, I doubt he is crawling underneath and bridging the actual solenoid nuts. I've done some reading on this and just wondering what your opinion is on fixing it. Replace the solenoid and see what happens? I shot him an email to get some more details but if its something lame or quick fix maybe offer him a little less, fix it and sell it? While I don't need 2 cherokees and I'd much rather keep the manual it seems like an opportunity to make a few bucks and jeeps seem to go quick around here, if it can be fixed of course... Thoughts?

 

[greg92jeepxj]

Ok , this Cherokee that you've got your eye on has a cranking problems . You'll want to put a volt meter on ground and the small gauge wire on the solenoid that is a trigger wire that is live in START position only . If it gives a reading when key is in crank , that would indicate the solenoid is not working. If the wire dosen't read voltage in start position , the ignition switch under the dash on the column is bad.
So now there is no spark from any plugs ? No signal on a ground wire on an injector harness plug either ? Must read that with a computer safe test light . Then the harness plug for the CPS will have to be checked with a voltmeter ( computer safe ) for reference 5 volts , ground and signal . That's three separate wires to be checked . It is best checked by back probing when cranking . The CMS ( cam position sensor ) is checked similar . Of no spark and no ground is found on the ground side of the injector harness plugs , both cam and crank sensors should be checked since both can produce a no start condition.

 

[liquidXJ]

SOLVED! My XJ is alive and kicking again. After much poking around, ignition, wires, plugs, etc.. We thought the ground on the fuel
sending unit looked a bit rusty and questionable. After taking a closer look it was hardly connected, hanging on by a thread masked by a small washer. Long story short pulled the whole unit out, disconnected the wires from the sending unit, cleaned it up reinstalled with a new o-ring and bam! She fired right up. It also doesn't start as hard as it used to which would make sense if there was a shitty ground. But it is working again and running great! There is a new problem of course but it's nothing serious, the fuse I suspect for the radio and interior light keeps coming loose which I don't care about the light but the radio now that's just annoying! Anyways I'll dig into that more tomorrow.

 

[greg92jeepxj]

Thank you so much for the update and very happy you've found the cause and corrected it. Your post will be very helpful to anyone who may have a similar problem and have a realistic item to look for that may be causing their problem as well. It really helpful when we post our success and solution but most of all very happy your jeep is running well . Sorry if I was off base but am happy that you've been able to continue on the right track . My suggestion on,y would have been a starting point but you got right to the problem and found the solution . Thank you again and your posts will always be welcome . Really , thanks for your help in what's needed so much in our forum , diagnostic repair and what to search for . Thanks

 

[volaredon]

you say "cranks but does not turn over" If it cranks, that IS "turning over" All "turning over" means is that the crankshaft spins when starter is engaged. Turning over has NOTHING to do with whether the engine fires, spits, sputters or anything of the sort.....

 

[money pit]

where exactly IS the CPS on a '96 ?

 

[JPNinPA]

On 4.0

 

[money pit]

Thanks.....so far mine is OK but I dread that thing going south on me !!!!