Buckey Posted March 11, 2007 Share Posted March 11, 2007 okay I changed the wire harness and engine in my comanche.Hooked up everything today and when I tried to turn it over there was nothing.So I checked battery and conections all good.So I got my test light out and started testing things I have power at the battery,power to the coil but nothing coming out of the coil,and no power at the starter.It is all hooked up properly I triple checked it.Any ideas of this problem???It's an 89 comanche with a 4.0 HO in it now.I had power for a phew minutes cause the lights came on and now nothing,it didn't even make a full rotation.Well help please. Buckey Link to comment Share on other sites More sharing options...
CWLONGSHOT Posted March 11, 2007 Share Posted March 11, 2007 Remove and clean battery connections. Also check condition of battery cables. I had simular problem a couple years back on a XJ. Turned out the batt cables and the connections at the battery that where bad. When I skinned back the insulation it was BLACK!!! One of the things I want to do is a complete new set of cables for my MJ. I am going to custom make the cables out of some very fine stranded high quality, 2/0 cable I aquired. :brows: I am also switching to all cable ends with a marine style battery connector. CW Link to comment Share on other sites More sharing options...
Buckey Posted March 12, 2007 Author Share Posted March 12, 2007 The cables are brand new as well.... Link to comment Share on other sites More sharing options...
CWLONGSHOT Posted March 12, 2007 Share Posted March 12, 2007 The cables are brand new as well.... Got a spare, known good coil?? I am also assuming there where no issues BEFORE this swap? CW Link to comment Share on other sites More sharing options...
BIGMASS Posted March 12, 2007 Share Posted March 12, 2007 I had power for a phew minutes cause the lights came on and now nothing,it didn't even make a full rotation. So you had powa for a while untill you tried to start it??? If so possible relay/fuse popped, don't know the electrics on these to well yet, just a thought. Link to comment Share on other sites More sharing options...
rocketwheels Posted March 12, 2007 Share Posted March 12, 2007 ....other than the relay popped idea....anytime you have juice and then nothing at all, check the ground at the battery and frame/motor 1st, then the next grounds in the system.... Link to comment Share on other sites More sharing options...
Pete M Posted March 12, 2007 Share Posted March 12, 2007 More often than not, the power-then-no-power problems I've experienced have been caused by poor connection at the battery terminals. Even ones that looked just fine would simply not let enough juice flow. A good cleaning with a wire brush usually fixes it. Link to comment Share on other sites More sharing options...
Buckey Posted March 12, 2007 Author Share Posted March 12, 2007 thanks guys if it doesn't snow or rain today I will try all that. Buckey Link to comment Share on other sites More sharing options...
Buckey Posted March 12, 2007 Author Share Posted March 12, 2007 ok I tightened all the grounds,battery,engine to frame and body to engine and then tried it,and it turns over.Now I have no spark to the coil at all.Is there a fuse someplace I can't find or something like that??? Buckey Link to comment Share on other sites More sharing options...
Kenosha Warrior Posted March 12, 2007 Share Posted March 12, 2007 Whoa.. you're in Trenton Ontario? I'm 20km's east of you man, over in Belleville. Its march break man, PM me an email, I may be able to come help you out with this sucker. Link to comment Share on other sites More sharing options...
Pete M Posted March 12, 2007 Share Posted March 12, 2007 The CPS on the transmission matches the new computer right? Link to comment Share on other sites More sharing options...
Buckey Posted March 12, 2007 Author Share Posted March 12, 2007 I used all the wire harness from the other truck and put it in the mj so everything matches up.Here is a question is it possible that the wire harness inside the cab is different??Also is there a sensor or something that the ignition needs to start.I have looked at everything even the CPS. I am runnin out of ideas and patience... HELP Buckey Link to comment Share on other sites More sharing options...
87manche Posted March 12, 2007 Share Posted March 12, 2007 I used all the wire harness from the other truck and put it in the mj so everything matches up.Here is a question is it possible that the wire harness inside the cab is different??Also is there a sensor or something that the ignition needs to start.I have looked at everything even the CPS. I am runnin out of ideas and patience... HELP Buckey if the CPS does not get a correct signal the ECU will not fire the coil. A few questions: Did you transfer over the HO computer, or just use it's wire harness? If you did transfer over the HO computer: Did you keep the HO CPS with the HO harness? Did you change the flywheel/flexplate with an HO variant. I believe the renix and HO flywheels are different. If you did not use the HO computer: Have you checked that the CPS connection is good? Did you use the HO CPS? If so, the Renix ECU doesn't understand it. You need a renix CPS. What you're describing is a classic no start symptom for a 4.0, and it's almost always related to the CPS. The ignition modules are fairly bulletproof, and have a very low failure rate. Link to comment Share on other sites More sharing options...
Scott86mj Posted March 12, 2007 Share Posted March 12, 2007 I used all the wire harness from the other truck and put it in the mj so everything matches up.Here is a question is it possible that the wire harness inside the cab is different??Also is there a sensor or something that the ignition needs to start.I have looked at everything even the CPS. I am runnin out of ideas and patience... HELP Buckey I used the fusepanel and wiring from inside the donor vehicle. I tried to do like you did but I had the same problem. Replace the interior harness and I bet it will crank. Also some of the connections inside will be a little different but if you still have the donor you should be able to figure it out. It is not to hard, label all your connectors and you should be fine. Link to comment Share on other sites More sharing options...
Eagle Posted March 13, 2007 Share Posted March 13, 2007 Okay, I sort of got lost as to what's original and what was swapped in, but here are some thoughts: 1) Is this an automatic? If so, how's the neutral safety switch? If it's a manual tranny and you swapped in anewer harness, somewhere in the early 90's Chrysler added a clutch safety interface -- the engine can't be started unless the clutch peddle is depressed. I don't know where that is or just what it looks like, but it's something to consider. 2) The CPS and ignition for the HO are totally different from the '87 - '90 Renix system. You have to use the CPS that matches the year of the engine and ignition -- the HO CPS won't talk to the Renix ECU, and vice versa. 3) In 1991 Chrysler rewired the entire vehicle, and one of the changes was to reverse the polarity of all the instruments. If you're wiring didn't take that into account, it may be possible that you fried something important, but I don't know enough about your swap to offer any guesses as to what might have been cooked. Best I can think of would be to get yourself the elctrical diagrams for the vehicle, and for the harness you swapped in. Replicate the replacement on paper and see if you can spot any areas where the polarity shift might have an effect on what you swapped in. Link to comment Share on other sites More sharing options...
Buckey Posted March 14, 2007 Author Share Posted March 14, 2007 Ok I will try to explane better. I have an 89 comanche and an 91 cherokee. The comanche engine was toast so I took out the engine in the cherokee(4.0 H.O.) including all the componants,wire harness,computer everything. I put it all in the comanche and nothing.It turns over and thats it. So I then today took out the intire wire harness out from under the dash of the cherokee and put it in the comanche.When I turned the key everything worked,clock,lights and even the fuel pump but still no spark to coil.So I checked the CPS like everyone told me still with nothing.(I even tried cutting the plug off and wiring it solid no luck)Is it possible the CPS in the trans is toast or could it be something else.Like a ground to the block off somewhere.I found a few wires that were not attached to anything just don't know where they go.Help please getting frustrated.. Buckey Link to comment Share on other sites More sharing options...
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