ParadiseMJ Posted October 30, 2013 Share Posted October 30, 2013 I finally got fed up with trying to finagle the wiring for my MJ, the AW4 swap, shifting issues, missing switches, lighting etc. etc. So, I scored a complete engine side wiring harness...same year, same set-up, 4.0 AW4... from C101 to A/C to TCU to ECU...I just unplugged it from the donor and plugged it in to my truck after I fixed all grounds, cleaned all the connectors. I kept the injectors wiring from the C101 from my harness intact. So, I got it all plugged in, checked the back-up lights, only starts in P or N, I also replaced the CPS and all four relays (RENIX), checked all the lighting...all good. Fuel pump primes, pressure at Schrader valve good, tested the tranny solenoids at the TCU connector, all good. One problem left...IT WON'T START!!! Cranks fine...no fire. Help me Obi-Wan Link to comment Share on other sites More sharing options...
Geonovast Posted October 30, 2013 Share Posted October 30, 2013 Was it a known good CPS? Link to comment Share on other sites More sharing options...
zagscrawler Posted October 30, 2013 Share Posted October 30, 2013 when you say no fire do you mean you checked for spark and there was none or it doesn't fire the engine up? Link to comment Share on other sites More sharing options...
cruiser54 Posted October 30, 2013 Share Posted October 30, 2013 Test the CPS first. You've got my instructions, right? Make sure your CPS is plugged into the correct connector. If the harness came from a donor that had the cPS wiring mod done, you could be plugging the CPS into a "dead" connector. Link to comment Share on other sites More sharing options...
zagscrawler Posted October 30, 2013 Share Posted October 30, 2013 paradise I feel for ya man. I should probably tell you I am no longer in the same boat as you. I went ahead and picked up the Rail II switch and am now running my trans in manumatic . soo I have a 92 HO aw4 comp and unmolested harness, accept for the trans plug of coarse, if you need anything out of it or the whole thing. Just let me know. I admire your drive to make this happen. I gave in and took the easy way out. keep at it man and let me know if you need anything. p.s. I really love that shifter, so do all my buddies, my wife will be on board soon also..... I hope lol take care bud. Nate Link to comment Share on other sites More sharing options...
kolton Posted October 30, 2013 Share Posted October 30, 2013 Check the grounds that connect to the Oil Dipstick Tube... Don't ask how I know... Link to comment Share on other sites More sharing options...
ParadiseMJ Posted October 30, 2013 Author Share Posted October 30, 2013 The CPS is brand new from the dealer. I will test it and the wiring again, as well as testing the wiring coming IN to the CPS. Replacing the CPS is/was a total B%$@!. I've done it before and it's only taken me about 30 minutes...this time was contortionism gone awry, in the rain, on a gravel driveway. I'm gettin' too flippin' old for this. Fire means it won't "fire up". I'm sure I have NO spark as I can hear the fuel pump prime and I tested the fuel pressure, with a gauge. I ran out of light (and patience) last night. I will test for spark today. My battery is suffering for all of this so it's on a charger as I type until I get home from work today. Don't know if that'll make a difference. The grounds on the dipstick are brand spankin' new, new bolt, new connectors, soldered. Tight and right. As far as the donor harness. I spent about 4 hours cleaning it, checking every connector, no bent pins, repaired all the "bubble gum" grounds with solder, shrink wrap AND tape. I was really meticulous about it . I super cleaned the C101 connector (both sides) and shined up every single thing I could find to shine. Link to comment Share on other sites More sharing options...
zagscrawler Posted October 30, 2013 Share Posted October 30, 2013 I don't mean to keep at it but you can have all the fuel pressure in the world but without injector pulses it won't fire either. If I remember right the same era ford efi wouldn't spark or pulse injectors if the distributer pickup or crank sensors were goofing up. Its been a while since I had to mess with them so I could be wrong. If you know someone with an injecter test light you could see if they are getting voltage properly. Good luck dude. Link to comment Share on other sites More sharing options...
ParadiseMJ Posted October 30, 2013 Author Share Posted October 30, 2013 CPS reads 241 on 2K ohm scale. .01 on VDC No spark at coil By the way...what CPS mod? The plug I'm plugging in to is the same plug I've been using all along. I kept that side of the C101 connector, I kept all the injector wiring as it was. Link to comment Share on other sites More sharing options...
cruiser54 Posted October 30, 2013 Share Posted October 30, 2013 Click on the following link and go to post 7. It's .5 AC volts minimum BTW. http://www.cherokeetech.com/VBull/showthread.php?3070-Cruiser-s-Mostly-Renix-Tips&p=103796#post103796 Link to comment Share on other sites More sharing options...
ParadiseMJ Posted October 31, 2013 Author Share Posted October 31, 2013 That's .1 VAC BTW, not .01 unless I'm doing this wrong. It doesn't seem like I did it the right way...since I'm getting such weird readings. Like I said, brand new from Jeep dealer. I'd expect it if I got the thing from AutoZone. So how would I test the wiring from the C101 TO the connector from to see if I'm plugged in to a dead circuit on the vehicle (harness) side. Link to comment Share on other sites More sharing options...
cruiser54 Posted October 31, 2013 Share Posted October 31, 2013 .1 is too low. It won't work me sending you the TSB in email. It's TSB 18-51-88 Link to comment Share on other sites More sharing options...
ParadiseMJ Posted October 31, 2013 Author Share Posted October 31, 2013 I may be starting to sound like a certain BMW/Jeep owner on "another forum" but the TSB (1 page) strikes me as somewhat vague on how the kit connects "directly" to the ECU. EDIT: OK I found the full version of the TSB and the fix. (6 pages) I don't believe this was already done on the donor as I simply unplugged everything and there was no "extra wires" at the ECU, but I'll look at the discarded harness. I'd rather NOT do this fix...but if I have to get this thing going I will. http://wagoneers.com/XJ/tech/CrankPositionSensor-87-90.pdf Link to comment Share on other sites More sharing options...
ParadiseMJ Posted October 31, 2013 Author Share Posted October 31, 2013 After perusing the TSB and checking the old harness and the new harness, the CPS mod has not been done on either Jeep. Wires and connectors are identical, so it should be plug n' play...I'll have to spend a bit more time testing before I give up the ghost on the new CPS. If anyone has another idea, lemme know. So is it at all possible to either INSTALL it incorrectly or a way to test and tell if the CPS is good before I even bring it home?? ... Link to comment Share on other sites More sharing options...
cruiser54 Posted October 31, 2013 Share Posted October 31, 2013 No "pre-test" on a CPS. Got drill? Link to comment Share on other sites More sharing options...
Geonovast Posted October 31, 2013 Share Posted October 31, 2013 Does your old CPS still work? Link to comment Share on other sites More sharing options...
ParadiseMJ Posted November 1, 2013 Author Share Posted November 1, 2013 No "pre-test" on a CPS. Got drill? Yes, got drill...since the thing isn't "testing" right (within spec...and not working, I figure what do I have to lose in tweaking it. Does your old CPS still work? It was still working when I removed the old harness...BUT...when I checked it out, I realized the insulation had melted (but it WAS working)...which is why I endeavored to replace it. When I replaced the harness it did NOT work, I figured it had finally given up the ghost. I actually have a "trail" spare, but what with the PITA in replacing the sensor itself, I want to be somewhat sure that I have a GOOD one. Link to comment Share on other sites More sharing options...
cruiser54 Posted November 1, 2013 Share Posted November 1, 2013 Drill that bad boy. Got the instructions? Link to comment Share on other sites More sharing options...
ParadiseMJ Posted November 1, 2013 Author Share Posted November 1, 2013 :thumbsup: Link to comment Share on other sites More sharing options...
ParadiseMJ Posted November 2, 2013 Author Share Posted November 2, 2013 OK... Here we go again. All the testing of the CPS has been done. Still get only .1 or .2...I also verified that the cylinders are getting fuel. Then I drilled it out and pressed it into the bell housing and tightened up the bolts. Tested the VAC again...got either 0.00 or an intermittent .1. So that CPS is toast, can't return it. Since the CPS seems to be the issue and not necessarily the new wiring bundle since the CPS is independently testing bad...right?? If the CPS tested good, and I still wasn't getting a spark, I'd go to the coil or ICM. Is there any other reason the CPS would test bad. I even took a look at the flexplate when I was recovering a lost CPS bolt :shake: . The flexplate is clean as a whistle. Remember, this is a Jeep Dealer CPS I'm really tempted to just go to AutoZone and get a cheapo CPS. Link to comment Share on other sites More sharing options...
Geonovast Posted November 2, 2013 Share Posted November 2, 2013 I would have thrown the original CPS back in just to see if it would fire. :dunno: Link to comment Share on other sites More sharing options...
ParadiseMJ Posted November 2, 2013 Author Share Posted November 2, 2013 There is that. Too late, it's at the landfill. After I saw the wire insulation was melted and I had the new Jeep CPS in hand I thought I had the "fix". So into the trash with the melted one. Link to comment Share on other sites More sharing options...
ParadiseMJ Posted November 3, 2013 Author Share Posted November 3, 2013 Resolution: I had done the sensor ground wire upgrade on the OLD wiring harness. When I replaced the harness...I did the same upgrade on the new harness...except I missed one of the ground wires. I tore open the new harness that I had all neat and tidy...and found the wire. I tacked it to the 3 grounds with a dab of solder, and it started right up. So I soldered it all together, shrink wrapped and taped it, put it all back together. Went for a drive. The good: It runs fine, I have a spare CPS (previously thought bad), my NSS and tranny wiring is good and tight (my back-up lights even work). Plus I can now swap out a CPS in about 20 minutes. The bad: I spent a couple days #$@^ing with this for a stinkin' 16 ga. ground wire. The tranny still does not shift quite right. Starts out in 1st, shift at 2K RPM into 2nd, then 3rd all in about 200 ft. So I still need to dial in the TPS and looking at it I've realized it's an Airtex. I might wanna swap that out, or even put the spare back in until I get it figured out. Link to comment Share on other sites More sharing options...
cruiser54 Posted November 3, 2013 Share Posted November 3, 2013 Are you $#!&ting me? It was the sensor ground wire in the new harness? Link to comment Share on other sites More sharing options...
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