Hello I am back again and need some help. I recently employed the services of an electrician to installed a alternator which I gave to him days before in order to make sure that everything was OK with it. After the site visit and he left I notice that I have no monitor lights on start up and cant rev the machine so I disconnect what he did and reinstall the old alternator and fuses that was burnt and was able to rev the machine to move it. There was only three lights on the monitor Alternator indicator, Engine oil pressure indicator and glow plug. the glow plug will remain on for about 30 seconds the out and now the batteries are not charging and the Alternator indicator light stays on. I tried another guy to help me but he too couldn't understand what was wrong all connection seem OK but still no charging, then I read some information on this forum concerning diodes and its only then I was able to locate the CHARGING problem, the Hitachi EX200-2 have five diodes on the harness one at the back next to the fuse-able link which has a long base and four behind the cab seat three short base and one long base. One of the short base diode that seem to be responsible for recharging the batteries and the lights on the monitor is burnt. I was able to switch around and test these three diodes and realized one was bad. I will like to replace this diode but cant seem to find and online information, part number not even an image of it. So here are photos of the short base diode I need. The 4288109 part number seem to be the long base diode. Here is what the short base diode look like. And lastly WHAT could be the reason for the Alternator light being on always despite the batteries are charging
That isn't the type of diode I'm familiar with but I've seen the problem you are talking about. The Isuzu engine has glow plugs that are connected by a metal strip across the tops. Look for one of the cross over strips to be rusted. That is an indication of one of the glow plugs being shorted out. Unhook the strip across the top of the plugs and you can test them in the machine. I've seen that short cause a diode behind the operator seat to burn out and cause the problems you speak of. The diodes I'm familiar with are two legs and the tops can be blue, yellow or black. I've gotten them through the Komatsu and Cat Dealers. Komatsu used a lot of them so they got expensive. I found one for a Cat but I don't have a part number that was about $2 US. I seem to recall the short circuit on the glow plugs causes a surge through the electrical system which blows through the diode. A working diode lets amperage go through it one way and not the other. On a working circuit when you turn on the key, current come through the light bulb and back to the alternator. The diode will let current flow in this direction. When the alternator is charging there is a higher voltage pushing back and the amperage would flow the other way and keep the light on but the diode just won't let amperage flow past so the light goes out.
Thanks John, I didn't paid any attention to that bar which is connected to the glow plugs because after replacing the burnt diode with a good one as shown in the pictures all lights and charging start working again. Now the main reason for wanting to replace this diode is that I will like to have my charging light shutting of and also be able to used my Dr. EX I no longer cant get connection with my Dr. EX and was wondering if all three diodes have to be working in order for me to do so. What I have notice is that the long base diode have two sections one with the two male pins connection and seem to be always white in color and the other part which I call the base comes in colors like yellow, blue or green in my case its gray. Here is what my long base diode look like and also a different view of my short base. I have used a warning light with bulb and wires connected to the alternator to make sure that it sending the signal to switch of the light and everything work fine, so I am asking could there be a problem with a diode in the monitor also
As long as the spade connections are the same a diode is a diode. I don't know that it will make any difference between long base and short base. So as far as I know find a cheap on and try it out. If all the diodes are good then hopefully all the functions should work. I don't know that there is a diode in the monitor panel. The only ones I'm familiar with are the ones behind the operator seat.
Thanks again John but I have already tried a Long base diode where I need the short one but there was no change the batteries wasn't charging and the monitor lights wasn't coming on. Base on you knowledge can you say that all the diodes behind the cab seat were the same to you. I went into my storage shed to have a look at my old harness which I had replaced but it seem that someone wanted it more than me so they stole it so back to square one
Hi guys There is a thread called ( Hitachi EX60 URG need electrical diagram) in it this diagram was posted of an ex100 diagram. If you can confirm your machine is the same as this i can probably help you with some of your questions. Cheers
Hello I have tried to compare the both layout and they are similar in way the ex200-2 just seem to have more. So i have post the layout of the ex200-2 which my help confirm what I am saying.
Here is the charging circuit for the EX200-2
You are correct there are quite a few differences. I have only found 4 loom diodes in that diagram you supplied maybe you can find the fifth and tell me?. The diodes i found will be standard silicone diodes prob around 10a rated. D1 and D2 are used to maintain power on the Monitor Controller logic controller. D1 is used when your ignition switch is in the on position. D2 is used when your ignition switch is in the Glow position. D3 is used to prevent the battery relay from back feeding power to the ignition switch once it has been enabled. D4 is a Flywheel diode to prevent the collapsing magnetic field in the coil of the battery relay from sending a voltage spike back into the system when the relay is disabled. D5 not found? What are your questions or symptoms again?
There are four diodes behind the cab seat and one of what I call short base is burn. I can no longer can get connected to my Dr. Ex. and my alternator indicator light stays on. I am trying to locate this diode that no one seem to have seen hoping that it may solve my problem
Is the machine charging yes/no? i see another thread where you were talking about leaving a wire off the alternator? did that get resolved. it would help if you knew which diode it is in the diagram. Diodes can be generally open circuit or shorted when faulty. The machine will run fine if D4 is open circuit and blow a fuse if shorted. D3 open circuit the battery relay would not energize and machine no start, short circuit the machine would start but not turn off. D2 open no warning lights in the glow position, shorted all your accessory's radio etc come on in the glow position. D1 open no warning lights with key in on position, shorted all accessory's come on in glow position. I think your Dr.EX plugs into PVC unit yes??? if so have it should have nothing to do with warning lights. PVC unit gets power from ignition through fuse 7. I can tell you what i think is happening but i need to know if it is charging ok. If you pop the cap off the diode you think is faulty and post a pick of diode i should be able to identify what sort it is at least. and one which is not burnt also. I know you say its burnt but how did you test it and is it shorted or open?
Thanks 007 my manual seem to be missing a fifth diode. I have located the long base one next to the battery relay and four behind the cab seat, one just as the one next to the battery relay and three short base as shown in the pics above. By switching around the diodes behind the seat I have realized if I disconnect. 1. The long base one the machine will not start. 2. One short base the alternator, oil pressure and glow plug dashboard lights will not come on. 3. Another short base is link to the battery charging system and all the other dashboard lights. 4. And lastly this one cant say exactly what it link to so I used it to get the charging system working so its vacant now. I am asking is their a error with the manual or harness. The manual is showing three behind the seat. I went searching all over the island asking if anyone have seen a diode like and they shook their heads they only seem familiar with the long base diode. One komatsu owner gave me long base one from his replaced harness which I have tried but still wasn't able to achieve much I recently replace all eight pc solenoid pilot valves and need to be able to used my Dr. EX in order to adjust their pressure correctly to achieve smooth muti-functions.
Thank again 007 that alternator was a self excited one which came with the machine and I have replaced it with a Hitachi EX200-2 alternator and yest the machine is charging I got 28 volts. The pics I have posted above showing the diode of what I called the short base is what I am having issues with. When installing the new alternator this issue started some of the lights were of the dashboard and the batteries were not charging and had to recharge them home in order to work the next day and by reading the same tread you suggested above I started looking at the diodes and by switching them around I realized the one will stop the function of the circuit wherever it is placed so I took one from another circuit and place it into that one which I assume bad and whala the charging system work and all lights came back. Since this issue started I cant get access to my Dr. EX. whenever I plug it in my EC. controller stop blinking and get a message say Not connected check controller power or communication harness. The Komatsu diode I have tried when I connected the Dr. EX. I was able to reach as far as selecting the type of machine and it will state that I am connected that size machine but wouldn't go further.
Firstly i do not know your machine or what Dr.EX is. I assumed it was a diagnostic tool and asked if it is plugged into the PVC module. When you say (The Komatsu diode I have tried when I connected the Dr. EX) just confuses me. Can i suggest you work on one issue at a time as the other might resolve itself. The easy one is your lights and charging and diodes should be resolved first. Sorry to be blunt but i think you are going to get yourself in more trouble the way you are going about trying to diagnose this. You really should be using a multi meter to test each diode. You can remove a diode and see what does not work but you cannot go moving them around to different spots. There will be large and small diodes to carry the additional current in the circuit and putting a small one where a big one should be will probably blow the diode. I am guessing the long based diodes probably have a larger diode inside. Carn't you pop the plastic top off and see the diode??? By using my info and the info you just told me you can mark the Diode numbers with a pen on the diodes to help work through it. You said the original alternator was self exciting and you replaced it with different alternator. So is the new one self exciting or have you altered the wiring to accommodate this new alternator, and have you reinstated the original wires????? This is important because your machine used to monitor the excitation circuit of your old alternator and is used in several locations in the loom for different functions. If you have done this correctly with the machine running the excitation voltage should appear on pin 4 of the Monitor Controller Logic Module and if it is there all the other places should be good unless you have altered your loom somewhere. You will need a voltmeter to test that.
Hello 007 I have a 1993 Hitach EX200-2 excavator and yes the Dr. EX is a diagnosis tool. There is a specific plug connection for it on the harness. This tool read information via the PVC and EC controllers. You have interpret me wrongly I said the machine came with a self excited alternator to me it was installed by the previous owner and I now have replaced it with a Hitachi EX200-2 alternator made for my Machine I am trying to get the alternator indicator light of the dashboard and also trying to locate that short base looking diode which I have posted pics of. Now for clarification purposes I have only switched around the three similar short base diodes and just by looking at the long base diodes I can see that they are different no switching took place with those. . I was told that all these similar looking diodes are the same that why I tried the one from a komatsu excavator which was given to me by the owner Now you have mentioned testing the diodes using a multi meter is resistance I should be looking for and in what range. The diodes are solid plastic not like other I have seen where you can peel back the colored rubber housing.
"Now you have mentioned testing the diodes using a multi meter is resistance I should be looking for and in what range." To test a basic diode with a meter use the 'resistance' mode (Ω). Diode resistances vary but the -important thing- is the resistance in one direction will be -many times greater- than the other. Measure the resistance between the two contacts, then reverse/switch the meter leads and measure resistance. In ONE DIRECTION it should read 10-1000 Ω for example. In the OTHER DIRECTION it should read infinity (or hundreds of thousands) Defective diodes will either read ZERO Ω -in both directions- or INFINITY (no continuity) -in both directions-.
Hello Daddieboy, The alternator indicator light is directly related to the excitation of your alternator. If your machine is as per the diagram you supplied it should be using a self excited alternator, so i am trying to find out what you think is different with the right one you have fitted. The Monitor Controller Logic Module is responsible for turning your alternator light on and off and it does this by monitoring the the excitation circuit of a self excited alternator. So as you can see i am concerned you say you fitted the right one for the machine so should i assume they are electrically the same.? This is a horrible thing i am going to suggest but would part way test if your new alternator is wired correctly. There is a starter relay in the loom which also monitors the same circuit and if it senses the alternator is charging it concludes the engine is running and prevents you from engaging the starter when the engine is running. So if you were very quick with the key with the engine idling see if you can engage the starter. If it does come in the excitation circuit is not correct on your new alternator and would explain your light also. Maybe you can take picture of the back of each alternator only showing the wires and plugs will help me. Glad to here you only switched small diodes around. I would not fit any non Hitachi diode as a test unless i checked the polarity of the diode first. Shame you cannot get cover off diodes but if you test and find faulty one i can select one for you from electronic online store and you can buy and solder in to replace old one. Should only be around 1 dollar cost. It sounds to me you are struggling at little so i will suggest the quickest and easiest method for you. Using ohms (resistance) measurement on a multi meter is not a good test for diodes. Some meters have a diode test function which is good and simple audible beep function is not to bad, but all can be miss leading if you are not experienced. I would recommend a couple of wires from your machine battery's with a small dash bulb in the circuit to test all of your diodes. A bulb of around 2watts 24Volt would be fine like the old dash board globes. So before you even start with diodes just touch the two wires together and the bulb should light up. If that works fine get one of your diodes and touch the wires on your diode terminals. The bulb should light up with the wires in one way and if you flip the wires around on the terminals of your diode the bulb should not light up. (Diode Good) So if light does not light up in ether direction. (Diode Bad) If light comes on in both directions. (Diode Bad) This is actually better test than meter because it passes more current through the diode that a multi meter can. Check all of your diodes and see how you go. By the way you can check the Komatsu diode same way and also check the bulb is on with the wires in the same position as the Hitachi ones. Unless you are certain the source and function of the Komatsu part I would be reluctant to assume the diode is a standard diode like the Hitachi ones are. It may in fact be a zenor diode which functions differently and would explain why your Dr.EX not connecting correctly.
Hello 007 the alternator was installed by the previous owner and they modify the harness to fit it. I have a new harness and alternator fitted now. here are pictures of the old and new. The new alternator and harness have plugs to match. I am a Architect trying to repair my machine because of my experience with unreliable repair guys in my area so the method with the bulb seem to be the easier for me so I will go that direction and relate my finding to you. Concerning the starter I dont fully understand the step by step details of what I should be doing to make sure what you have explain is taking place. Please explain further.
Hello Daddieboy, No problem being Architect good to see you are giving it a go at repairs. The pictures are good, I assume the old alt was 130200Pic Can you tell me how many terminals are in the plug on the 130244Pic. The starter test is simple start the machine and then see if you can engage the starter when the engine is running. Only hold the key in the start position for a short period of time. One of two things will happen. You will hear a loud metallic noise from the starter. Or you will here nothing and the starter does nothing. Come back to me and tell me what happened.