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Thread: Hitachi EX60 URG need electrical diagram

  1. #1
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    Hitachi EX60 URG need electrical diagram

    No prior electrical problems but now the starter (key) switch produces nothing. Turning the ignition on lights the dash lights and the fan and other accessories work.

    I can engage the starter by jumping the high-amperage solenoid located just inside the engine door and putting +24v to the white-red wire (running to the starter solenoid) on the same unit. So the starter and it's interconnecting wiring is all functional.

    If I could find a wiring diagram showing the basic pieces and wire colors of the starter circuit I could trouble shoot it much easier. Anyone have a service manual handy, or at a minimum can describe what I should see (i.e., measure) happening at the solenoid when the key is turned to start?

    I also find it odd the heavy red wire which is ultimately switched to the white-red on the small side of the solenoid has no juice in it...so even if the solenoid did engage, it has no _24v to send to the starter. I have a feeling the lack of +24 at the red wire is part of my problem.

  2. #2
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    24 volts?

    Don't catch it on fire or melt the harness mate.
    It's a 12 volt system.
    Did you say there is no power at the main wire at the starter. Should be 12V all the time.
    Get a multimeter and check both ends for a start

  3. #3
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    yes, 24v

    No question it is 24 volts; (2) 12v batteries in series. It's a grey market machine, isuzu diesel, if it matters....

    There is battery power to the starter solenoid, and it'll crank if I jumper the solenoids. Problem is the solenoid has 1/2 dozen low-amperage inputs going to it, so I need to know what to test for to see why the key switch is not activating it.

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    If your unit is the same as the larger Hitachi I believe you are describing what they call a safety relay. It prevents the starter from engaging if the engine is already running. Also it disconnects the starter once the engine starts. It does this by a signal from the alternator. The regulator in the alt. can fail a diode and and the voltage leak will make the safety relay prevent the starter from working. There should be only two wires from the main harness that activate the safety relay. One will be the signal from the key switch. The other will be the signal from the alternator. you can test it with a light or a volt meter. Also be aware that there could be two fuses (fusible links) usually at the electric battery disconnect. One is live with the key off the other is live with the key on.

  5. #5
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    still looking

    my starting problem likely resides in the starter safety relay - I really need a wiring diagram to trouble shoot. Does anyone have a scan of the starter electrical diagram for any similar sized hitachi EXxx? This is a mid-90's machine w/the isuzu diesel engine. there was an ex200 starter diagram posted here earlier but too fuzzy of an image to read.

  6. #6
    Senior Member -3Doc's Avatar
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    Try this it is for an ex100 hope this helps!
    Attached Images Attached Images  

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    thanks -3Doc

    thanks for the ex100 diagram....the basic components and # of wire connections & their letters at each component look equal to mine...from memory anyways. I'll compare it to the machine tonight.

    Kind of curious what's meant by the "load damp relay"? It looks like it's purpose is to keep the battery relay energized (via a signal from the alternator) if the engine is still running even if the key switch is turned to off?

  8. #8
    Senior Member -3Doc's Avatar
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    Quote Originally Posted by allpinball View Post
    thanks for the ex100 diagram....the basic components and # of wire connections & their letters at each component look equal to mine...from memory anyways. I'll compare it to the machine tonight.

    Kind of curious what's meant by the "load damp relay"? It looks like it's purpose is to keep the battery relay energized (via a signal from the alternator) if the engine is still running even if the key switch is turned to off?
    You are right that is exactly what it does, then as soon as the engine stops it "dumps" the load on the electrical system.

  9. #9
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    did you ever figure it out?

    Looks like I have the same problem with the same model excavator. Did you ever figure out what was wrong?

  10. #10
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    I have the same problem with the same model. What was the solution?

  11. #11
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    fix

    Quote Originally Posted by chuck767 View Post
    I have the same problem with the same model. What was the solution?
    In my case the starter solenoid was burnt out. It took me a while to figure out how it got damaged. Here's what I found (with the help of the above ex100 diagram which is close enough for the ex60urg):
    - The excavator hadn't been used for a while and the ignition lock had started to seize
    - I started the engine and drove away, not realizing that the key was stuck in the START position, it hadn't returned to RUN by itself
    - There's a circuit (safety relay, see machine's post above) that cuts off the starter once the engine (alternator) is running but in my case the alternator belt had come so loose the alternator didn't spin and therefore didn't cut the starter
    - I drove the excavator for 20 mins and during that time the starter motor must have been running and the solenoid was engaged the whole time which caused it to burn out and seize

    I got a new starter off ebay (~ $150 iirc) and managed to put it in without dropping the engine but it was still a pita. And yes, I replaced and tightened the belt (batteries are charging now, nice). And lubed the ignition lock.

    Btw, big thanks to everybody who posted information on this thread. It allowed me to fix the ex myself for cheap instead of paying big money to have someone come out and repair it.

  12. #12
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    Thanks Maxa,

    I think my problem has something to do with the safety relay. I have a boat with Hino diesel engines and had a similar problem and it was the safety relay. Ironically my alt is not charging and I need get that addressed too. Wish it was just the belt but I think it is something more serious.
    Regards,
    Chuck

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