LoTGoD Posted November 30, 2009 Share Posted November 30, 2009 Will an ECU from an 88 auto work to at least get my 90 manual started? I have access to a friend's MJ that was originally a manual, but was converted to an AW4. All I am looking to do is get it to fire up and verify that my ECU is bad. Will this be an issue if I put his ECU in my MJ? Thanks! Aaron Link to comment Share on other sites More sharing options...
mjeff87 Posted November 30, 2009 Share Posted November 30, 2009 I'm running an 89 auto ECU in my 87 with an AX15.....no problems here. Jeff Link to comment Share on other sites More sharing options...
LoTGoD Posted November 30, 2009 Author Share Posted November 30, 2009 I'm running an 89 auto ECU in my 87 with an AX15.....no problems here. Jeff That is VERY good to know Jeff. So if that is the case, then the auto ECU's are backwards compatible with the manual tranny, but not the other way around? I'm confused now as to why there would 2 different ECU's.... Link to comment Share on other sites More sharing options...
mjeff87 Posted November 30, 2009 Share Posted November 30, 2009 I imagine it has something to do with the TCU in the auto harness and the extra TPS output.....I'm actually running the entire auto engine bay harness (swapped it in when I converted to a 4.0L). I have the extra TPS output hooked up, but it does nothing......and I jumped the NSS wiring as well. Jeff Link to comment Share on other sites More sharing options...
Wildman Posted December 1, 2009 Share Posted December 1, 2009 :agree: Just to try to get your MJ fired up, I'd think a automatic ECU (#5428) should work :hmm: The auto ECU gets input thru the TCU, the NSS is not there, and should not hamper the engine starting, and the only other thing that would make a big difference is the brake switch, tied into the TCU to 'slow down' the tranny. Give it a try and see where it gets you :D It's not like your going to be putting a couple hundred thousand miles on it.......are you??? Link to comment Share on other sites More sharing options...
LoTGoD Posted December 1, 2009 Author Share Posted December 1, 2009 Nope...no miles...and still no start! I pulled his ECU out, and swapped it in. Nada, zip, zilch, nothing! Mine in his and his fires right up. That lets me assume my ECU is good. Sorry Wildman...looks like I won't be needing that one from you after all. I'm stuck again. Let's recap what I've done so far:[*:b21eiqep]Replaced CPS (original one was melted a bit from contact with the header)[*:b21eiqep]Tested and verified new CPS (read 202 Ohms)[*:b21eiqep]Removed coil and verified in another MJ[*:b21eiqep]Removed starter solenoid and verified in another MJ[*:b21eiqep]Verified voltage in sync signal in distributor[*:b21eiqep]Verified fuel pump, B+ latch, and O2 heater relays[*:b21eiqep]Tried both (good) engine and ECU harnesses Let me pose 2 questions now: 1. Does it matter in the least that the steering column in it is out of a an auto? I removed the kick-down cable that attached to the column that allows the key to be turned back when the auto was put in park. I now have to manually push that rod back up in towards the steering wheel to get the key to release from the run position to the off position. Is there something missing here that would cause it not to start? 2. What is the minimum in-cab wiring that I need to have it fire up? I currently have the 4 connectors on the steering column (2 connectors that I believe are the power that goes to the starter, 1 is blue, and one is black, and connect to the top right of the steering column) The other 2 on the column are the very wide connector at the right most portion, and the headlight hi-beam connection. I also have the fuel pump wiring and rear lights connected. I have no gauges, nor any other connector attached. I have a ground wire connected directly from the battery to the mounts of the ECU to make darn sure it is grounded. Is this minimal setup good enough for it to fire up? Again, I appreciate all the support I've had on this. I'll get it, as I am slowly eliminating everything under the sun! Link to comment Share on other sites More sharing options...
aerocorey Posted December 1, 2009 Share Posted December 1, 2009 I haven't been following your no start thread, but I've been where you are. Have you tried pull or roll starting it? If you haven't, try it. Mine wouldn't fire itself off from the starter, and the starter was fine, but it would roll start everytime. There's a TSB that fixed my truck. I suggest you give it a shot, and see if I can find the TSB and post it up if you roll start okay... Link to comment Share on other sites More sharing options...
LoTGoD Posted December 1, 2009 Author Share Posted December 1, 2009 I haven't been following your no start thread, but I've been where you are. Have you tried pull or roll starting it? If you haven't, try it. Mine wouldn't fire itself off from the starter, and the starter was fine, but it would roll start everytime. There's a TSB that fixed my truck. I suggest you give it a shot, and see if I can find the TSB and post it up if you roll start okay... Were you getting any spark or fuel? I'm getting neither, so I doubt a roll start will help me. Link to comment Share on other sites More sharing options...
mjeff87 Posted December 1, 2009 Share Posted December 1, 2009 this is a 2.5 -> 4.0 swap, right? using the cab harness you got from Pat? What engine harness are you using (manual or auto)? if it's an auto harness, you have to jump the NSS (jumper wire between pins A and E, or splice the two wires together). Are all of the grounds hooked up under the hood, especially the ones behind the dipstick and the one @ the back of the head to firewall? Jeff Link to comment Share on other sites More sharing options...
LoTGoD Posted December 1, 2009 Author Share Posted December 1, 2009 this is a 2.5 -> 4.0 swap, right? using the cab harness you got from Pat? What engine harness are you using (manual or auto)? if it's an auto harness, you have to jump the NSS (jumper wire between pins A and E, or splice the two wires together). Are all of the grounds hooked up under the hood, especially the ones behind the dipstick and the one @ the back of the head to firewall? Jeff Jeff, No engine swap. Mine had the 4.0 Renix in it when I got it. Engine harness and ECU harness are from Pat's 89 manual trans parts Jeep. Interior harness is also the new one from Pat. All engine side grounds are hooked up and connecting bolts are tight. Link to comment Share on other sites More sharing options...
mjeff87 Posted December 1, 2009 Share Posted December 1, 2009 just to clarify.....you are getting cranking but no run? or is the starter not even engaging? Link to comment Share on other sites More sharing options...
LoTGoD Posted December 1, 2009 Author Share Posted December 1, 2009 just to clarify.....you are getting cranking but no run? or is the starter not even engaging? Starter is good. Plenty of cranking going on, just no spark and no fuel :D Link to comment Share on other sites More sharing options...
aerocorey Posted December 1, 2009 Share Posted December 1, 2009 Were you getting any spark or fuel? I'm getting neither, so I doubt a roll start will help me. No, I was not. The TSB I'm referring to has to do with the CPS wiring. Your CPS may ohm good, but these trucks have too much resistance in the wiring between the ECM plug and the CPS plug. Replacing just the CPS does nothing for this defect. I'm not sure why roll starting worked for me, but I SUSPECT the reason it worked is because during a roll start my crank was turning faster than during a regular start. Perhaps this faster crank rotation provided a readable signal for the ECU to work with to get the truck breathing on its own. In any case, it wouldn't start with the starter, no fuel, no spark, but it would roll start every time. I had a dealer perform this TSB, and now my mother is DDing the MJ while I'm overseas with no issues. I won't push the issue any further if you think it's a waste of your time, but a roll start is free. Give it a shot... EDIT: Here's a link to the TSB. http://wagoneers.com/XJ/tech/WIRING/CrankPositionSensor/CPS-87-90-update.pdf I did a home-brewed version of this that made the truck behave for a few weeks before it fell victim to the cheap crappy connectors I used. I just drilled a hole in the firewall, cut the CPS wires, cut the ECM wires, and spliced them together. Link to comment Share on other sites More sharing options...
LoTGoD Posted December 1, 2009 Author Share Posted December 1, 2009 Were you getting any spark or fuel? I'm getting neither, so I doubt a roll start will help me. No, I was not. The TSB I'm referring to has to do with the CPS wiring. Your CPS may ohm good, but these trucks have too much resistance in the wiring between the ECM plug and the CPS plug. Replacing just the CPS does nothing for this defect. I'm not sure why roll starting worked for me, but I SUSPECT the reason it worked is because during a roll start my crank was turning faster than during a regular start. Perhaps this faster crank rotation provided a readable signal for the ECU to work with to get the truck breathing on its own. In any case, it wouldn't start with the starter, no fuel, no spark, but it would roll start every time. I had a dealer perform this TSB, and now my mother is DDing the MJ while I'm overseas with no issues. I won't push the issue any further if you think it's a waste of your time, but a roll start is free. Give it a shot... EDIT: Here's a link to the TSB. http://wagoneers.com/XJ/tech/WIRING/CrankPositionSensor/CPS-87-90-update.pdf I did a home-brewed version of this that made the truck behave for a few weeks before it fell victim to the cheap crappy connectors I used. I just drilled a hole in the firewall, cut the CPS wires, cut the ECM wires, and spliced them together. Hmmmm....interesting point. I would give that TSB a shot, if I didn't already verify Ohm readings at the ECU connector. There was barely a 5 Ohm loss from the connector to the ECU, and that is well within spec. I'll try the rolling start as soon as I can get it out of the garage! Link to comment Share on other sites More sharing options...
aerocorey Posted December 1, 2009 Share Posted December 1, 2009 Aaahhh, I didn't catch that you ohmmed it from the ECM. I'm probably wasting your time if that's the case, but it may still be interesting to try the roll. Good luck with the no start! Link to comment Share on other sites More sharing options...
LoTGoD Posted December 2, 2009 Author Share Posted December 2, 2009 Ok...this is going to be a really stupid question, and I hesitate to even ask... Do I HAVE to push the clutch in to start the MJ? Since I have no seats in, I've not been getting inside the Jeep to try and start it...just making sure it is in neutral and then turning the key. I don't see any wiring connectors on the clutch pedal/mechanism that would tell me I had to depress the clutch pedal to get it to start.... Obviously I could try it, but I just thought about it this morning, and I am at work now. Link to comment Share on other sites More sharing options...
mjeff87 Posted December 2, 2009 Share Posted December 2, 2009 no, no ignition interlock on the early models (my TJ has one, but I bypassed it :D ) Link to comment Share on other sites More sharing options...
mjeff87 Posted December 2, 2009 Share Posted December 2, 2009 shot in the dark here, but do you have all the fuses installed in the fuseblock? Specifically, IIRC there's a 25 or 30 amp ignition fuse there....see if it's good or not (or missing) Jeff Link to comment Share on other sites More sharing options...
LoTGoD Posted December 2, 2009 Author Share Posted December 2, 2009 shot in the dark here, but do you have all the fuses installed in the fuseblock? Specifically, IIRC there's a 25 or 30 amp ignition fuse there....see if it's good or not (or missing) Jeff I checked them before I put that fuse block in. I'll re-check them tonight. Link to comment Share on other sites More sharing options...
LoTGoD Posted December 3, 2009 Author Share Posted December 3, 2009 Spent the better part of an hour on the phone with a good friend and very knowledgeable Jeep guy last night. After explaining in detail everything that I have done so far, he had 3 suggestions: 1. Replace ignition module 2. Replace CPS again 3. Replace sync signal generator in distributor. Looks like I have a plan...again :headpop: Link to comment Share on other sites More sharing options...
Wildman Posted December 4, 2009 Share Posted December 4, 2009 :hmm: I'd vote for #2 Because of this.......... viewtopic.php?f=2&t=17900&hilit=no+start+xj Your getting an Ohm's reading on the CPS, right :hmm: But........your still not getting fuel, correct???? Did you pull out a plug to check if it wet?? Want me to stop on my way by next week??? Too many questions for you??? Link to comment Share on other sites More sharing options...
LoTGoD Posted December 4, 2009 Author Share Posted December 4, 2009 :hmm: I'd vote for #2 Because of this.......... http://www.comancheclub.com/forums/view ... o+start+xj Your getting an Ohm's reading on the CPS, right :hmm: Yep...Ohm reading was 202 last time I checked it (last week). I'll swing by the dealer today at lunch for a new one. I used a Crown Automotive one last time, so I might as well get an OEM one this time. But........your still not getting fuel, correct???? Correct Did you pull out a plug to check if it wet?? Yep...all 6 plugs...visually they are not wet...nor do they smell of fresh fuel Want me to stop on my way by next week??? If you are going to be anywhere near me and have the time, I would appreciate it more than you could ever imagine! If you really can stop, send me a PM and we'll get the day and time setup, along with my address. Heck, I'll even take an afternoon or day off of work! Too many questions for you??? I've been answering everyone's questions on this for the last month, so a few more will never be a problem! Aaron Link to comment Share on other sites More sharing options...
Wildman Posted December 5, 2009 Share Posted December 5, 2009 PM sent with the info. The spark, yea, might be a brand new CPS. The not getting fuel.........has me stumped :hmm: Unless........you have more than one major problem there. Bad right hand shock tower :hmm: You checked the fuseable links there, correct? Did you ever check the relays on the shock tower, for the fuel pump......the 2nd one from the front? Did you try to jump the fuel pump yet? I'm thinking........get fuel to the rail first, then work on the spark issue. Link to comment Share on other sites More sharing options...
aerocorey Posted December 5, 2009 Share Posted December 5, 2009 The not getting fuel.........has me stumped :hmm: Unless........you have more than one major problem there. I disagree. The ECU controlls spark and fuel. It times the firing of each plug and each injector using crank and cam position sensors. Why would it fire any of the injectors if it doesn't know when to fire? I think whatever is killing your spark is killing your injection as well. A bad coil pack or a bad module or any of the other spark specific components aren't going to kill both spark and fuel. Google "renix fuel injection" and you'll find a link to a FSM that lists the crank and cam position sensors as input sensors for injection, and those will kill spark too... I realize it doesn't make sense sense to you, and I said I wouldn't bring it up again, but did you try a roll start yet? It's cheaper than throwing another crank sensor at it, and if it works OR doesn't work it will tell you something either way. If you've got your heart set on replacing a part, I like the cam position sensor before another crank sensor. Cam sensor is easier to replace and you haven't changed it yet. Link to comment Share on other sites More sharing options...
Wildman Posted December 6, 2009 Share Posted December 6, 2009 I'll agree, but what I was getting at........way back on another topic from Lotgod, he's also not getting any pressure on the fuel rail........correct??? That's what has me stumped. I posted the links from Eric Giordano, which I do think Lotgod did do the test on the CamPS. The problem with roll starting this MJ is, if it's not getting any fuel at the rail, or the injectors for that mater......and no spark what so ever, just what is roll starting going to do???? Maybe what you experienced with your MJ, push starting it just bypassed a bad battery cable, weak battery, or bad starter relay :dunno: If the CPS or the CamPS is bad.........you can push start this for 100 miles, it still will not start. Link to comment Share on other sites More sharing options...
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