wiring problems with 743 bobcat

[superniceguy5687]

Browsing through the thread, to refresh my memory, it occurred to me that there may be some confusion about what "solenoid" is being talked about. I propose that the one mounted to the top of the starter, with the big battery cable attached, be called the "solenoid". The two small ones, mounted up under the air filter, I would like to call "relays"; one for the starter and one for the glow-plugs. That is how they appear on my schematic: (16) is the "Pre-Heat Relay" and (17) is the "Start Relay". My understanding is that when wire 21S (WHT/L. GRN) is connected to the (starter) solenoid you have the "continued cranking problem". And, if 21S is disconnected, then you can jumper at the starter between the big power stud and the small stud (for 21S) and the engine will start and then run fine; no continued cranking (as long as you remove the jumper after it starts!). Is that all correct? If so, then reconnect wire 21S and disconnect Chassis Connector (4). Then try starting it with the jumper and see if it is OK. None of the electricals should work like that, no glow plugs, alternator charging, lights, etc. but it should start. We will be chasing this back one connector at a time. If it works OK with connector (4) disconnected, then I will have you reconnect that and disconnect Harness Connector (1) and try again... If it isn't OK with just (4) disconnected, then try with both (4) and (1) disconnected.

Good day Sir: Sorry it has taken me so long to post. I have done three attempts of your suggestions. First I will say thank you for helping me with this. The first thing I did though was to take the blue/orange wire off of the glow relay. I did this in order to glow the glow plugs separately so I was able to get it started and running. Attempt #1: All wires were put back onto the starter. There was a red and green one tied together from the factory, a red one which went to the other side of the glow plug relay,and the big + from the battery. These all connected to the big top lug on the starter. Then 21S was put back to the little lug. Connector #4 and connector #1 (there is two of them) are still connected together. Key was not in or turned on, the ignition switch. Glowed, turned over and fired up. Seemed to run okay. Put my multi meter on battery posts, battery seemed to be charging. Meter was fluctuating from 14.68-14.69 V. Result: While it was running the hour meter was ticking away. After about 1/2 hour of running, I shut the engine off and the hour meter kept ticking away. Seemed to turn itself off after approx. a minute. Before I had the fire, it would not quit ticking and the only way I could get it to turn off was to unhook the battery. Attempt #2: All wires where hooked up as in attempt #1. No key in ignition and ignition not turned on. Glowed the glow plugs separately as in attempt #1. Both of connector #1 are still together. This time I now disconnected connector #4 as you suggested. Started it up, and let it run again this time for only about 15 minutes. Result: After shutting engine off. Hour meter was ticking again this time it seemed to last for approximately two minutes before it shut off. It was also running while the engine was running. Will have to repost as I am running out of room.

 

[superniceguy5687]

Browsing through the thread, to refresh my memory, it occurred to me that there may be some confusion about what "solenoid" is being talked about. I propose that the one mounted to the top of the starter, with the big battery cable attached, be called the "solenoid". The two small ones, mounted up under the air filter, I would like to call "relays"; one for the starter and one for the glow-plugs. That is how they appear on my schematic: (16) is the "Pre-Heat Relay" and (17) is the "Start Relay". My understanding is that when wire 21S (WHT/L. GRN) is connected to the (starter) solenoid you have the "continued cranking problem". And, if 21S is disconnected, then you can jumper at the starter between the big power stud and the small stud (for 21S) and the engine will start and then run fine; no continued cranking (as long as you remove the jumper after it starts!). Is that all correct? If so, then reconnect wire 21S and disconnect Chassis Connector (4). Then try starting it with the jumper and see if it is OK. None of the electricals should work like that, no glow plugs, alternator charging, lights, etc. but it should start. We will be chasing this back one connector at a time. If it works OK with connector (4) disconnected, then I will have you reconnect that and disconnect Harness Connector (1) and try again... If it isn't OK with just (4) disconnected, then try with both (4) and (1) disconnected.

Attempt#3: All wires remained connected as before to the starter. Blue/orange wire from glow relay is still disconnected as before. Connector #4 is now re connected together. Both of connector #1 as there is two of them are now disconnected. No key in ignition and ignition is not turned on. Glowed it, and it started. Checked with my multi meter on the battery and the battery seemed to be charging. I forgot to post in 2nd attempt, put my multi meter on battery and battery seemed to be charging was at 14.68-14.69V. The same happened in this attempt it was 14.68-14.69V. Let it run for approximately 15 minutes, and seemed to be okay. This time while it was running the hour meter was not ticking. Also, after I shut the engine off, the hour meter was not running or ticking. Don't know where to go from here. Not sure if the hour meter should even be running without the ignition switch not even being turned on. Hope that this is understandable and detailed enough. I was glowing it separately so that I didn't have to use the ignition switch. Don't know if that is right or not but it seemed to. Shall wait for your reply. Sorry it has taken me so long to post. I always seem to be to busy sometimes. You do not have to apologize I have lots of patience. Once again cant thank you enough for helping me out.

 

[billrbg]

Attempt#3: All wires remained connected as before to the starter. Blue/orange wire from glow relay is still disconnected as before. Connector #4 is now re connected together. Both of connector #1 as there is two of them are now disconnected. No key in ignition and ignition is not turned on. Glowed it, and it started. Checked with my multi meter on the battery and the battery seemed to be charging. I forgot to post in 2nd attempt, put my multi meter on battery and battery seemed to be charging was at 14.68-14.69V. The same happened in this attempt it was 14.68-14.69V. Let it run for approximately 15 minutes, and seemed to be okay. This time while it was running the hour meter was not ticking. Also, after I shut the engine off, the hour meter was not running or ticking. Don't know where to go from here. Not sure if the hour meter should even be running without the ignition switch not even being turned on. Hope that this is understandable and detailed enough. I was glowing it separately so that I didn't have to use the ignition switch. Don't know if that is right or not but it seemed to. Shall wait for your reply. Sorry it has taken me so long to post. I always seem to be to busy sometimes. You do not have to apologize I have lots of patience. Once again cant thank you enough for helping me out.

Okay, I'm thinking the Transmission Charge Pressure Switch (7) may be sticking and just takes a while to open its contacts when the engine is stopped. Reconnect both of the connectors (1) and remove wires 35H (YEL/BRN), 32T (YEL/BLK), and 32PT (YEL) from Pressure Switch (7). Put and ohmmeter across those two Pressure Switch terminals and see if it goes from "open circuit" to "closed" when the engine is started. The see if the switch contacts return to "open" quickly after the engine is stopped, or if it take a while. Keep those three wires (35H, 32T, 32PT) insulated well enough so they don't short to ground while you are doing this. IMPORTANT: Is the starter run-on issue gone now, you can crank with the key and then it quits cranking when key is released?

 

[superniceguy5687]

Okay, I'm thinking the Transmission Charge Pressure Switch (7) may be sticking and just takes a while to open its contacts when the engine is stopped. Reconnect both of the connectors (1) and remove wires 35H (YEL/BRN), 32T (YEL/BLK), and 32PT (YEL) from Pressure Switch (7). Put and ohmmeter across those two Pressure Switch terminals and see if it goes from "open circuit" to "closed" when the engine is started. The see if the switch contacts return to "open" quickly after the engine is stopped, or if it take a while. Keep those three wires (35H, 32T, 32PT) insulated well enough so they don't short to ground while you are doing this. IMPORTANT: Is the starter run-on issue gone now, you can crank with the key and then it quits cranking when key is released?

Good day: I will attempt to what you posted. And will re post the results to you. I have not however attempted to have all the wires hooked up to the way the schematics show. I other words I have not attempted to start it up with the key as of yet. Been swamped as usual. Hopefully I will get to it the day after tomorrow. Should I re hook up the glow plug lead back to the relay, and attempt to glow it with the key as well. I have also noticed too that the back up alarm doesn't work with the new harness. Could it be the switch for that? I shorter out the alarm to a battery and it seemed to work. If it goes back to re cranking itself where would one go from there? I could try and take a whole bunch of pictures and try a post them in file where I had the schematics. I could take pictures of the harness from behind the instrument panel and of the starter and the relays, etc. Hope all is well. Will repost after I do your other test. Thank you

 

[billrbg]

Good day: I will attempt to what you posted. And will re post the results to you. I have not however attempted to have all the wires hooked up to the way the schematics show. I other words I have not attempted to start it up with the key as of yet. Been swamped as usual. Hopefully I will get to it the day after tomorrow. Should I re hook up the glow plug lead back to the relay, and attempt to glow it with the key as well. I have also noticed too that the back up alarm doesn't work with the new harness. Could it be the switch for that? I shorter out the alarm to a battery and it seemed to work. If it goes back to re cranking itself where would one go from there? I could try and take a whole bunch of pictures and try a post them in file where I had the schematics. I could take pictures of the harness from behind the instrument panel and of the starter and the relays, etc. Hope all is well. Will repost after I do your other test. Thank you

Darn, I was hoping we were past the starter issue. I would like to focus on that, since it burns up the starter and is far more critical. Go back to my reply on 11/22/2015, that's the procedure I would follow to resolve the starter. If anything isn't clear, let's talk... You can reconnect the glow wire (28B), but it will be inop while you are doing those tests disconnecting (4) and the (1s). Just manually jumper to that stud for 28B on the glow relay to get glow, pretty much like you are doing now.

 

[superniceguy5687]

Darn, I was hoping we were past the starter issue. I would like to focus on that, since it burns up the starter and is far more critical. Go back to my reply on 11/22/2015, that's the procedure I would follow to resolve the starter. If anything isn't clear, let's talk... You can reconnect the glow wire (28B), but it will be inop while you are doing those tests disconnecting (4) and the (1s). Just manually jumper to that stud for 28B on the glow relay to get glow, pretty much like you are doing now.

Good day sir: Hope all is well. For the starter tests they were in previous post with attempt #1- attempt#3. I will try and start it with the key again and see what happens. It seemed to start and run okay by jumping it. When I had #4and#1 both of them disconnected and put my digital multi meter on battery posts did did seem to charge the battery. Would the battery charge without the key turned on? Just wondering. I made 3 attempts to start with out the key in the ignition or turned on ( previous post) that why I was wondering if you wanted me to take pictures of all of my hookups to everything?

 

[billrbg]

Good day sir: Hope all is well. For the starter tests they were in previous post with attempt #1- attempt#3. I will try and start it with the key again and see what happens. It seemed to start and run okay by jumping it. When I had #4and#1 both of them disconnected and put my digital multi meter on battery posts did did seem to charge the battery. Would the battery charge without the key turned on? Just wondering. I made 3 attempts to start with out the key in the ignition or turned on ( previous post) that why I was wondering if you wanted me to take pictures of all of my hookups to everything?

" Attempt #1: All wires were put back onto the starter. There was a red and green one tied together from the factory, a red one which went to the other side of the glow plug relay,and the big + from the battery. These all connected to the big top lug on the starter. Then 21S was put back to the little lug. Connector #4 and connector #1 (there is two of them) are still connected together. Key was not in or turned on, the ignition switch. Glowed, turned over and fired up. Seemed to run okay." *******Okay, I was missing a key element there. You had all wiring connected, but were jumpering for glow and cranking, not using the key-switch. Repeat that procedure enough times that you are confident that starting it that way avoids the "starter run-on" problem. Since there are no "reply numbers" on posts here, it might help if you indicate date/time for previous posts that you want to reference. I'll have to study the schematic some more, but I doubt the alternator should charge the battery when the key is in the "off" position.

 

[mark18mwm]

" Attempt #1: All wires were put back onto the starter. There was a red and green one tied together from the factory, a red one which went to the other side of the glow plug relay,and the big + from the battery. These all connected to the big top lug on the starter. Then 21S was put back to the little lug. Connector #4 and connector #1 (there is two of them) are still connected together. Key was not in or turned on, the ignition switch. Glowed, turned over and fired up. Seemed to run okay." *******Okay, I was missing a key element there. You had all wiring connected, but were jumpering for glow and cranking, not using the key-switch. Repeat that procedure enough times that you are confident that starting it that way avoids the "starter run-on" problem. Since there are no "reply numbers" on posts here, it might help if you indicate date/time for previous posts that you want to reference. I'll have to study the schematic some more, but I doubt the alternator should charge the battery when the key is in the "off" position.

billrbg, I agree with everything your saying, great advise. But, I think ( and I may be wrong though, trust me, it happens. lol) the alt may charge with the key off IF it's a one wire alternator. The reason I say that is the batt post is always hot on a alt. So if its turning it should charge. if its not a single wire alt I would think your right about not charging. Keep up the good work, your coaching him through this well.

 

[billrbg]

billrbg, I agree with everything your saying, great advise. But, I think ( and I may be wrong though, trust me, it happens. lol) the alt may charge with the key off IF it's a one wire alternator. The reason I say that is the batt post is always hot on a alt. So if its turning it should charge. if its not a single wire alt I would think your right about not charging. Keep up the good work, your coaching him through this well.

I'm glad somebody else is keeping an eye on this thread, it would be too easy for us to get "lost in the weeds" with all these wire numbers/colors and connector numbers. It is not a 1-wire alternator, though. The output stud (wire 1B) and one of the small terminals (wire 14F) are "always hot", in fact they both connect to the big "battery" terminal on the starter solenoid. The other small alternator wire (wire 14R) goes to a splice and changes to 12C (nice,huh?) then continues to the Back-Up Alarm (4). There it changes to wire 12B and is powered, I think, from the Ignition Switch (23). As I recall, the OP is also having a problem with the BU alarm, so maybe we are homing in on right area...

 

[billrbg]

I am not upset, we are here to help each other. If a thread does start to annoy me, I'll just back away from it quietly. I am, however, confused! It still isn't clear to me if the starter "cranks by itself" when all wires are removed from the small stud on the solenoid; when there is NO possibility of there being voltage applied there. Yes or No, does it ever crank when there is no wire connected to that small solenoid stud?

How about posting a picture of the "wire side" of both the Ignition Switch and Back Up Alarm?

 

[mark18mwm]

How about posting a picture of the "wire side" of both the Ignition Switch and Back Up Alarm?

Ok, I was hoping it may have been a one wire alt to make it a bit easier for him. I am not familiar with a 743, I was just thinking of some equipment wiring in general. I am down to thinking the ignition switch or switch plug in on the harness might be built incorrectly or may be the wrong switch and be causing the problem. For a ign switch it might look identical to the one removed but might be different internally. The contacts might be different so as the start position is energized when it is in the run position. I say this even knowing they are (switch and harness) are new. They may have been incorrectly assembles or might have been the wrong part in the right box or bag from the dealer. I'm sure you guys will get her straightened out, you are doing a good job working it out.

 

[Bobcatdan]

Ok, I was hoping it may have been a one wire alt to make it a bit easier for him. I am not familiar with a 743, I was just thinking of some equipment wiring in general. I am down to thinking the ignition switch or switch plug in on the harness might be built incorrectly or may be the wrong switch and be causing the problem. For a ign switch it might look identical to the one removed but might be different internally. The contacts might be different so as the start position is energized when it is in the run position. I say this even knowing they are (switch and harness) are new. They may have been incorrectly assembles or might have been the wrong part in the right box or bag from the dealer. I'm sure you guys will get her straightened out, you are doing a good job working it out.

First mistake was rebuilding a burnt 743, should have scrapped it. My guess is the harness coming down from the cab was misrouted and pinched causing stuff to short to one another..

 

[Tazza]

First mistake was rebuilding a burnt 743, should have scrapped it. My guess is the harness coming down from the cab was misrouted and pinched causing stuff to short to one another..

I rebuilt a 743 that was burnt, i did re-wire it from scratch, so i got to wire it the way i wanted to.

 

[superniceguy5687]

How about posting a picture of the "wire side" of both the Ignition Switch and Back Up Alarm?

Good day Mr. Bil lrbg: I will take a whole lot of pictures and get them posted under my folder in the pictures as soon as I get a chance. Have been super busy lately. My apology but will be a couple days.

 

[Madbobcater743]

Good day Mr. Bil lrbg: I will take a whole lot of pictures and get them posted under my folder in the pictures as soon as I get a chance. Have been super busy lately. My apology but will be a couple days.

I'm excited to see the pictures in all honesty . My 743's wiring is hanging by a thread. I know I'll be in it before the winter. Hour meter seized, no fuse I could keep going. Pictures help by so much its not even funny. Hows that saying goes?

 

[Fefanatic]

I'm excited to see the pictures in all honesty . My 743's wiring is hanging by a thread. I know I'll be in it before the winter. Hour meter seized, no fuse I could keep going. Pictures help by so much its not even funny. Hows that saying goes?

Start it and pull the start relay from the socket. If it continues to try to start then you need to look between starter and relay wiring. If it doesn't try to start then connect a test light to the relay wire coming from the ignition switch. If the test light flickers or comes on then start checking wiring back to the ignition switch. Disconnect the start wire at the ignition switch and run the unit again with the test light on the relay plug. If there is no flickering or the light does not light up then you probably have a defective ignition switch. Just because it's new doesn't mean it's any good.

 

[Madbobcater743]

Start it and pull the start relay from the socket. If it continues to try to start then you need to look between starter and relay wiring. If it doesn't try to start then connect a test light to the relay wire coming from the ignition switch. If the test light flickers or comes on then start checking wiring back to the ignition switch. Disconnect the start wire at the ignition switch and run the unit again with the test light on the relay plug. If there is no flickering or the light does not light up then you probably have a defective ignition switch. Just because it's new doesn't mean it's any good.

Can anyone tell me what the Diode trio in the altenator charges/operates? Does it operate anything?

 

[Madbobcater743]

Can anyone tell me what the Diode trio in the altenator charges/operates? Does it operate anything?

Also this is my altenator. Is it a melroe or the other one? I'm Such a noob. Sh!tty cellphone pic I know.

 

[walio123]

Can anyone tell me what the Diode trio in the altenator charges/operates? Does it operate anything?

Аlternator produces alternating current. Diode serve to manage the direction. If there is a blown diode will not have a charge. You can check them with an ohm meter. In one direction must have a conductivity, and as a tester swap cables should not have.

 

[billrbg]

Аlternator produces alternating current. Diode serve to manage the direction. If there is a blown diode will not have a charge. You can check them with an ohm meter. In one direction must have a conductivity, and as a tester swap cables should not have.

Where are you getting the term "Diode Trio"? At one time (maybe still) that was a term Delco used for a smaller rectifier that powered the alternator's internal voltage-regulator. The main power rectifiers (six of them) were called the "Rectifier Bridge". This was a "10-SI Delcotron System", new stuff in 1969. As I recall, the starter on my 743 is Delco, so I wouldn't be surprised if the alternator is too. I'll be near mine later today, I may brave the mud and go take a peek... A picture of the other end of the alternator, the wiring end, may tell me more about yours.