wannabeMJ Posted October 9, 2010 Share Posted October 9, 2010 well I tried to start the truck and I got no power to the fuel pump started checking the wires and they are fine I also check the fuel pump (jumped it) worked fine also then I went to the fuel relay (ceramic thingy on the fender) and it read 1.1 homs as suppose then I check the power to the 2 or/bk that go there and I got nothing I also check many wires at the XJ/MJ connections and I got nothing coming out of there could it be the computer is fried??? 86 MJ 4.0L AX15 I followed the XJ/MJ wirring to the letter I'm sure its fine the battery is good to how can I check the comp.. Link to comment Share on other sites More sharing options...
wannabeMJ Posted October 9, 2010 Author Share Posted October 9, 2010 nobody ?? I'm going nuts here trying to find the prob :fs1: I also found out there is a lot more things with no power........ no whipers no heater motor plz I need hints or info :hmm: Link to comment Share on other sites More sharing options...
Pete M Posted October 9, 2010 Share Posted October 9, 2010 you might have fried one of the fusible link wires near the battery. Link to comment Share on other sites More sharing options...
wannabeMJ Posted October 9, 2010 Author Share Posted October 9, 2010 not sure where it is would that still allow the truck to crank ? Link to comment Share on other sites More sharing options...
Pete M Posted October 9, 2010 Share Posted October 9, 2010 could be. a fusible link is a short piece of wire designed to fail and protect the rest of the harness. there are a few of them all clustered together somewhere over by the battery. maybe at the starter relay? been a while since I've thought about them. they are funky looking compared to the rest of the harness. the way to inspect them is to pull them and check for continuity. Link to comment Share on other sites More sharing options...
wannabeMJ Posted October 9, 2010 Author Share Posted October 9, 2010 ok found them fuze link they are all good anything else? Link to comment Share on other sites More sharing options...
Eagle Posted October 9, 2010 Share Posted October 9, 2010 According to your post, this is a 1986 MJ ... with a 4.0L engine and an AX-15 tranny? Who swapped the wiring harness, and what year vehicle did it come out of? Link to comment Share on other sites More sharing options...
wannabeMJ Posted October 9, 2010 Author Share Posted October 9, 2010 lolll forgot that part 90 cherokee I did the swap unplug and plug that's it BY the way I just redid my battery wire 1 going to the starter 1 going to the power relay 1 ground to engine mount/frame 1 power relay to alt could that have messed it up? seems all good acording to the HAYNES Link to comment Share on other sites More sharing options...
Eagle Posted October 10, 2010 Share Posted October 10, 2010 The wiring is different from '87 to '88, and again from '88 to late '89, so Haynes probably isn't the best possible source. So if you used a '90 harness, you don't have a C101 connector to worry about -- although that wouldn't affect power into the harness. Begin at the beginning, Grasshopper. Power runs from the battery to the main power connector stud on the starter relay. From there, you should have a #8 red going to the starter solenoid, and several fusible link wires. The fusible links should be (according to my 1988 factory electrical manual) a green #18 that transitions to a red #12 feeding the ignition switch, and a #12 blue that transitions to a #8 red and connects to the alternator. The fuel pump relay and the ECM both get power through the same fusible link. That one is an Orange #20 that transitions to a red # 14. It splits into four, a #14 red feeding the fuel pump relay, a red feeding the TCU (note says "with auto trans only" so I don't know if your harness will have it), a #16 red feeding the ECU, and a #14 red leading to connector C106 -- whatever the heck that is. Link to comment Share on other sites More sharing options...
wannabeMJ Posted October 10, 2010 Author Share Posted October 10, 2010 TY eagle will look in to that tommorow but what you said seems right and if my memory isn't f*cking with me that's what it looks like Link to comment Share on other sites More sharing options...
wannabeMJ Posted October 10, 2010 Author Share Posted October 10, 2010 how can I tell if I got power to the cpu? Link to comment Share on other sites More sharing options...
Eagle Posted October 10, 2010 Share Posted October 10, 2010 Terminal B7 on the ECU. It should be a red wire feeding it. It's labeled "BAT" on the schematic -- dunno if it'll be marked that way on the ECU. According to the plug diagrams, B7 is in the smaller, rectangular plug, that has two rows of 12 pins. B7 is the bottom row, with #1 at lower left and #12 at lower right. (Lower refers to the smooth edge, not the edge with the snap fittings on it). Link to comment Share on other sites More sharing options...
wannabeMJ Posted October 13, 2010 Author Share Posted October 13, 2010 just found that on the net http://www.cherokeeforum.com/f2/ecu-help-1694/ will give it a try and see Link to comment Share on other sites More sharing options...
wannabeMJ Posted October 13, 2010 Author Share Posted October 13, 2010 well I'm a idiot :doh: what's the main difference between an electrical pump and a mechanical pump the power that goes to it ........... where does the power come from ...... the ECU where does the ECU take the power..... the ignition switch what is the only part that I kept from the comanche ......... the steering column I just bought the cherokee ignition switch and guess what ......I got power :thwak: Link to comment Share on other sites More sharing options...
Eagle Posted October 13, 2010 Share Posted October 13, 2010 "Power to the people." I love it when a plan comes together. Link to comment Share on other sites More sharing options...
wannabeMJ Posted October 13, 2010 Author Share Posted October 13, 2010 now it starts tanks all Link to comment Share on other sites More sharing options...
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