Appstate97 Posted June 21, 2017 Share Posted June 21, 2017 I.s. Note 32E. I have a copy. Cruiser I checked the manuel that ohm sent and found connector C101 on page 75. Thanks for giving me the pins to check. I'll check pins 2E and 3E with ignition off and on to check volts. I'll post with numbers. Any idea what could be causing the drop in power to the fuel pump? Wha is a resistor retrofit? Link to comment Share on other sites More sharing options...
Ωhm Posted June 21, 2017 Share Posted June 21, 2017 When you jumper the FP relay, pin C216_1(30) to C216_4(87) the vehicle started and ran just fine. That can only mean we did something right. Is that where we are right now, vehicle starts and runs with jumper? No voltage drops at fuel pump with jumper? Not sure about C101, that goes to the INJ harness. cruiser54, I understand Link to comment Share on other sites More sharing options...
Appstate97 Posted June 21, 2017 Share Posted June 21, 2017 When you jumper the FP relay, pin C216_1(30) to C216_4(87) the vehicle started and ran just fine. That can only mean we did something right. Is that where we are right now, vehicle starts and runs with jumper? No voltage drops at fuel pump with jumper? Not sure about C101, that goes to the INJ harness. cruiser54, I understand I am unable to jump the fuel pump from pin 30 to 87. I can jump the fuel when I go from + batt. to pin 87. Link to comment Share on other sites More sharing options...
Ωhm Posted June 21, 2017 Share Posted June 21, 2017 Measure voltage at C216_5(86) with the key on (relay removed). Measure voltage at C107_D2-4 with the key on (relay doesn't matter). Should be the same. Link to comment Share on other sites More sharing options...
Ωhm Posted June 21, 2017 Share Posted June 21, 2017 Add one more measurement. Measure voltage at C216_1(30), (relay removed) should read B+ voltage. Link to comment Share on other sites More sharing options...
Appstate97 Posted June 21, 2017 Share Posted June 21, 2017 Measure voltage at C216_5(86) with the key on (relay removed). ***11.70*** Measure voltage at C107_D2-4 with the key on (relay doesn't matter). RELAY REMOVED *** D2: .02. D3: 10.8. D4: 11.72 Should be the same. Link to comment Share on other sites More sharing options...
Appstate97 Posted June 21, 2017 Share Posted June 21, 2017 Add one more measurement. Measure voltage at C216_1(30), (relay removed) should read B+ voltage. C216 fuel pump relay pin 30: .08 Link to comment Share on other sites More sharing options...
Appstate97 Posted June 21, 2017 Share Posted June 21, 2017 I measured the volts at the red wire splice and got a reading of .08 with the ignition on. - what should it be reading? 12volts? I just tried supplying the bottom of pin 30 on the fuel pump relay 12 volts from a jumper off of the + batt (relay plugged in and ignition on) and was unable to get the fuel pump to turn on. As soon as I touched the + batt jumper to pin 87 the fuel pump turned on. Link to comment Share on other sites More sharing options...
Ωhm Posted June 21, 2017 Share Posted June 21, 2017 Add one more measurement. Measure voltage at C216_1(30), (relay removed) should read B+ voltage. C216 fuel pump relay pin 30: .08 Sounds like were're back to splice E (red). Need to confirm B+ voltage at the following point: Disconnect and measure voltage at C103_B (Engine Harness side). Side note on Diagnostic Connectors (refer to pg 18): C106 is the connector #, also known as D1 followed by pin #. C107 is the connector #, also known as D2 followed by pin #. I'll stop using C106 and C107 and just call them D1-pin# or D2-pin#. So when I ask for D1-5 it mean pin 5, not pins 1 through 5. Just because I understand me doesn't mean others do. Sorry about the confusion. Link to comment Share on other sites More sharing options...
Appstate97 Posted June 21, 2017 Share Posted June 21, 2017 Thanks for the clarification. How many volts should the red wires have with ignition on? 12v? Link to comment Share on other sites More sharing options...
Ωhm Posted June 21, 2017 Share Posted June 21, 2017 Splice E is hot at all times. Key position doesn't matter. Link to comment Share on other sites More sharing options...
Appstate97 Posted June 21, 2017 Share Posted June 21, 2017 I just tried supplying the bottom of pin 30 on the fuel pump relay 12 volts from a jumper off of the + batt (relay plugged in and ignition on) and was unable to get the fuel pump to turn on. As soon as I touched the + batt jumper to pin 87 the fuel pump turned on. ** Any idea why giving 12v of power to pin 30 on the fuel pump relay wouldn't trigger the pump on? Link to comment Share on other sites More sharing options...
Ωhm Posted June 21, 2017 Share Posted June 21, 2017 That's the job of the fuel pump relay to supply B+ from pin 30 to pin 87, when the relay is grounded (picked) through the ECU. That's why splice E is hot. Link to comment Share on other sites More sharing options...
Ωhm Posted June 21, 2017 Share Posted June 21, 2017 Need C103_B voltage (engine harness side), that's what supplies splice E with voltage. Link to comment Share on other sites More sharing options...
Appstate97 Posted June 21, 2017 Share Posted June 21, 2017 Need C103_B voltage (engine harness side), that's what supplies splice E with voltage. The volt meter isn't picking up a reading. None of the engine side pins are showing a reading. Link to comment Share on other sites More sharing options...
Ωhm Posted June 21, 2017 Share Posted June 21, 2017 The harness with both splice E and splice F is called the engine control (EC) harness. Can you measure C103_B on both sides of the connector, when disconnected? We need B+ on the engine (E) harness side. Link to comment Share on other sites More sharing options...
Appstate97 Posted June 21, 2017 Share Posted June 21, 2017 The engine side didn't show a power voltage reading on the B pin. Link to comment Share on other sites More sharing options...
Ωhm Posted June 21, 2017 Share Posted June 21, 2017 Pull the relay out. Take measurements from the pin to any ground. Refer to the following link: http://www.bteventures.com//mj1988electricalmanual.pdf Engine schematic: pg 14 Harness view: pg 89 & 90 Connector view: pg 75 C106_D1-5 is the connector with the yellow cover on it. Thanks for the resource. I cleaned and reinstalled the dipstick ground, 4 relays, connectors near it, and C101 connector. I checked C106 D1-5 and only got a reading on the batt. Pin (5.6 reading). C103 B got a reading of .12. All readings had the ignition on and everything reinstalled. Well way back in post #26, I see your voltage reading for C103_B was 0.12vdc, not 12vdc as I thought. Your problem is Fuse Link G is blown. Don't know much about replacement Fuse Links. Maybe someone can help here. Link to comment Share on other sites More sharing options...
Appstate97 Posted June 21, 2017 Share Posted June 21, 2017 Its like the EC harness isn't getting power from the ECU. Can I check power for the FUel pump relay at C101? Is there away to bypass this set of wires? I was thinking about buying a new relay/fuse and using the extra/leftover hot wire off of the starter relay to create a new relay for the fuel pump. Link to comment Share on other sites More sharing options...
Ωhm Posted June 21, 2017 Share Posted June 21, 2017 EC harness gets power from Fuse Link G for the fuel pump. C101 goes to the Injector harness, nothing to do with fuel pump or the fuel pump relay. I don't want to burn your MJ to the ground. Wait and see if others can chime in on Fuse Link replacement or inline fuse replacement. Link to comment Share on other sites More sharing options...
Appstate97 Posted June 21, 2017 Share Posted June 21, 2017 Will do, Thanks Link to comment Share on other sites More sharing options...
Jeep Driver Posted June 21, 2017 Share Posted June 21, 2017 I'm not going to decipher this thread.......... Are you referring to the fused links that come off the starter relay and run back into the harness? Link to comment Share on other sites More sharing options...
cruiser54 Posted June 21, 2017 Share Posted June 21, 2017 EC harness gets power from Fuse Link G for the fuel pump. C101 goes to the Injector harness, nothing to do with fuel pump or the fuel pump relay. I don't want to burn your MJ to the ground. Wait and see if others can chime in on Fuse Link replacement or inline fuse replacement. Check your email. Link to comment Share on other sites More sharing options...
Ωhm Posted June 21, 2017 Share Posted June 21, 2017 Yep, on fuse links Link to comment Share on other sites More sharing options...
Jeep Driver Posted June 21, 2017 Share Posted June 21, 2017 Any good auto parts store will have the links. You'll need to go back to clean wire, solder and heat shrink, also I would solder the connector end and heat shrink that also. I don't know what the values are, no one I asked knew either, I'm going to guess at 25-30 amps but they are slow burning, I would not replace with a standard fuse. OP, no work around, no by-pass........replace the link. Link to comment Share on other sites More sharing options...
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