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81 xj650 maxim wiring clusterf%*k

Discussion in 'XJ Technical Chat' started by Dstrong77, Oct 10, 2017.

  1. Dstrong77

    Dstrong77 Member

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    OK back again for advice. The bike is a heavily modified 81 xj650 maxim. I have a Clymer manual and a complete spare parts bike. I have access to the minimal wiring diagram and the factory wiring diagram. I left the bike out in 2days of constant rain and have since encountered lighting issues. The previous owner has some "interesting" wiring changes.

    The fuses have been replaced with inline blade fuses. the headlight relay failed a while back and has been replaced by me with a toggle switch which can now be removed and the relay installed with a replacement that I now have. The OEM dash speedo and tach have been replaced with a small set and there are no neutral or indicator lights. I have a mess in the headlight with wires being bypassed and what not.there is a small circuit board that has been removed from the dash (i believe) which just has about 4 or 5 resistors on a small green board. I don't know if it is necessary to have there or not. My problem in trying to diagnose the lighting issues( no brake light or turn signals) is that I have somehow disconnected something that prevents the bike from starting. I don't want to go much further. The starter does not engage when I push the button. Fully charged battery. I am tempted to pull all the wiring off my parts bike and redo the whole kit and kaboodle.but knowing how much the previous owner modded the wiring I am unsure how many problems that will give me. I am also tempted to just go full minimal and get rid of the factory wiring all together. It is seriously a mess in there and I am wondering if anyone knows what has to be hooked up inside the light for the engine to fire, Obviously the started wires but any other circuits. I would appreciate some advice. I will get some pics tomorrow
     
  2. Rooster53

    Rooster53 Active Member Premium Member

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    This sounds like the diode block. I believe on the 81 Maxim it should contain two diodes and a resistor. One diode is essential for the headlight relay to function as it rectifies the output of the AC Generator and applies that power to the headlight relay coil to energize the coil, which is then latched closed by an internal diode in the headlight relay.

    The other diode resistor pertain to the oil light. The resistor is needed to have a functioning oil light. The diode is needed to illuminate the oil light as a check when the starter button is depressed.

    So, bottom line you need the diode block installed on a stock harness.

    The starter will not engage unless the starter cutoff relay is engaged and applying 12V to the starter solenoid. This is part of the safety circuit. The contacts should close when the bike is in neutral OR the clutch lever is pulled in. The clutch switch wiring would be inside the headlight bucket, the neutral switch wiring should not be affected by wiring in the headlight bucket other than it is routed / spliced to go there for the neutral light.

    So, first make sure the Ignition Fuse is OK, as it supplies power to the safety circuit as well as the TCI / Ignition Coils. The starter will not engage if the fuse is blown.

    Also, the 81 Maxim utilizes handlebar ground for the starter switch, so the right control and handlebars must be assembled and mounted to provide a path to ground for the starter switch. With the stock setup, it is a nice feature having the oil light illuminate when the starter button is depressed as this indicates not only that the switch is functioning, but also that the ignition power is present.

    Did you solve this issue? Does the horn work? If the horn is also not working then all of the signal circuits would be dead (excepting neutral light that you do not have connected). So, look at signal power starting at the fuse.
     
  3. Dstrong77

    Dstrong77 Member

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    Not yet but that is great information. I haven't been back out to work on it, however, I do have some pics of the diode block. I am sure that the starter has lost its ground somehow I first want to get the bike started so I can isolate that issue and then go on to fixing the lights. The right switch has not been removed so it should be grounded there. The horn was removed by PO and all main fuses are not blown. I will trace the starter wires first and figure that out. All turn signals and brake lights are aftermaket put on by PO so I just need to get to the bottom of it but I appreciate the info on the starter selenoid and diode block that at least gives me more info than I have. The wiring digrams help but it is helpful when people can get you going in the right direction. I was worried I would be opening a can of worms by stripping the harnesses of my parts bike
     

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  4. Rooster53

    Rooster53 Active Member Premium Member

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    Well that photo is certainly not the diode block, but something the PO added. It would be hard to guess at what they were doing; maybe some LED lighting or something like that. The diode block is normally a small rectangular block covered with a rubber boot.
     
  5. Dstrong77

    Dstrong77 Member

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  6. Dstrong77

    Dstrong77 Member

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    I have everything working properly now except the turn signals.I cannot get that figured out. I have tried 2 relays, 2 different handlebar switches. I am unsure how to test the relay. Is there anything else besides the relay and the switch that could prevent the turn signals from working? Does anyone know how to test relay?
     
  7. Rooster53

    Rooster53 Active Member Premium Member

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    Need more details on what parts you are using - stock flasher and bulbs, aftermarket etc? It could be as simple as insufficient load for the chosen relay, which normally presents as illuminated bulbs that do not flash. The stock flasher relay requires 27 watt bulbs to work correctly.

    Battery or +12V to "B", a load connected to "L", and load return connected to battery negative and the relay should work. Note as above that many flasher relays are load dependent and will only work with the specified bulbs.
     
  8. Dstrong77

    Dstrong77 Member

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    OK That is helpful. I will look into that. I know I can hear current enter the relay when the key is turned to on.One little click is what I hear. I did have a solid light (non-flashing) condition last week one day, the next day it was flashing. the next day it stopped working and has not worked since. So possibly insufficient current coming to the relay. Does that current come from the switch or what would be a good way to check that?
     
  9. Dstrong77

    Dstrong77 Member

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    all turn signals are aftermarket.
     
  10. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

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    That breadboard makes me think that ether the PO was tying to use the wrong type of resistor to use LED turn signals, or that he was attempting to replicate a missing diode block without knowing what was inside.
     
  11. Rooster53

    Rooster53 Active Member Premium Member

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    And what about the flasher? If you are trying to use the OEM flasher with aftermarket turn signals that have lower wattage bulbs then it is not going to work.

    The flasher relay (B) terminal is wired directly to +12V getting its power from the signal fuse.

    The flasher relay (L) terminal goes to the common input on the turn signal switch, the switch will then select left or right signals. You can temporarily install a jumper on the flasher relay mating connector shorting Br to B/W to test the signals. With those two shorted you should be able to select the left or right signals and verify both the front and rear illuminate.

    The flasher relay (C) terminal goes to the auto cancel unit. When you turn the ignition on this pin should go to 12V to disable the OEM flasher. When the turn signal selector switch is pushed left or right the (C) terminal should go low enabling the flasher relay. If the auto cancel is not reset, either because of a defective auto cancel unit or defective turn signal switch or wiring the flasher will not operate. You can just disconnect the auto cancel unit to verify if it is contributing to the no signal issue.
     
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  12. Dstrong77

    Dstrong77 Member

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  13. Dstrong77

    Dstrong77 Member

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    Everything is working now. After all your thoughts I dug a lil deeper. There was another relay tucked away in the wiring loom. All taped up and hidden. Aftermarket relay. The stock turn signal relays are still on the bike but apparently don't go anywhere. The aftermarket relay was faulty. (and well hidden)! I'm all good now no more hand signals. Thanks, guys I probably wouldn't have dug so deep if you wouldn't have mentioned aftermarket relay and leds. I knew I had aftermarket bulbs but didn't know that 2 of them are LED. I appreciate it.
     
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