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Old 07-06-2020, 07:48 AM   #1
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I'm in over my head on this 1990 thomas/chevyb60 rewiring project.

Hello there friends. I have gotten myself in over my head in my bus rewiring project. I didn't mean to go this deep! But here we are. I'm all up in there.



My bus is a 1990 thomas body, chevy b60 chasis. I've gotten most of what I believe to be the thomas electrical system sorted out, and am now trying to sort out the chaos near the fusebox. Many things have been torn apart by previous owners. Most of the things I need to work do at this point, but there is alot of loose dangly bits that I would like to finish stripping out while I'm this deep in here, during a pandemic without much to do.



So, first question; is the fuse box that lives under the dashboard on the firewall part of the chevy system? I can't find any reference to it in the thomas wiring diagram that seemed to more or less match my bus.



Question 2; does anyone have a diagram for said fusebox and surrounding area.



Question 3; I have three relays that all have the same main number on them, and same little diagram, (not counting the horn relay). First of all. anyone have any guesses on what they could be?



I am no expert in relays, but every relay I can find online has it's pins labeled with numbers (30,85,86, 87, 87a). This one has A, C, D, E, and F. all of them have what I assume to be a common ground in F. There is a pink wire that I believe to be an ignition hot in all of D. 2 have C wired but not A, and one has A but not C. If I am reading this correctly, which I absolutly might not be, does this mean that when I turn the key to on, E sends power to C? but E becomes disconnected from A?



What would a relay be doing that disconnected when I turn my key on? The wire in A is purple if that helps. I'm still untangling things down there, but it seems as tho the purple wires may have gone to a system of some sort that is obsolete at this point, as I see a few different places to plug things into the purple circuit that are unused.



Thank you so much if you've read this far. I hope y'all can help me, cuz I'm going a little crazy here!
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Old 07-06-2020, 10:08 AM   #2
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Quote:
Originally Posted by Raye View Post
Hello there friends. I have gotten myself in over my head in my bus rewiring project. I didn't mean to go this deep! But here we are. I'm all up in there.



My bus is a 1990 thomas body, chevy b60 chasis. I've gotten most of what I believe to be the thomas electrical system sorted out, and am now trying to sort out the chaos near the fusebox. Many things have been torn apart by previous owners. Most of the things I need to work do at this point, but there is alot of loose dangly bits that I would like to finish stripping out while I'm this deep in here, during a pandemic without much to do.



So, first question; is the fuse box that lives under the dashboard on the firewall part of the chevy system? I can't find any reference to it in the thomas wiring diagram that seemed to more or less match my bus.



Question 2; does anyone have a diagram for said fusebox and surrounding area.



Question 3; I have three relays that all have the same main number on them, and same little diagram, (not counting the horn relay). First of all. anyone have any guesses on what they could be?



I am no expert in relays, but every relay I can find online has it's pins labeled with numbers (30,85,86, 87, 87a). This one has A, C, D, E, and F. all of them have what I assume to be a common ground in F. There is a pink wire that I believe to be an ignition hot in all of D. 2 have C wired but not A, and one has A but not C. If I am reading this correctly, which I absolutly might not be, does this mean that when I turn the key to on, E sends power to C? but E becomes disconnected from A?



What would a relay be doing that disconnected when I turn my key on? The wire in A is purple if that helps. I'm still untangling things down there, but it seems as tho the purple wires may have gone to a system of some sort that is obsolete at this point, as I see a few different places to plug things into the purple circuit that are unused.



Thank you so much if you've read this far. I hope y'all can help me, cuz I'm going a little crazy here!
Not a Thomas guy, but I do understand relays. You are exactly wrong the E-C-A relationship. When the relay is in the resting position, power is flowing from E to C. When D is given power, it closes the loop between D and F, which switches the power flow from E to A, rather than E to C.

I'm not even going to begin to guess what any of the relays are for, it could be a dozen different things.
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Old 07-06-2020, 10:18 AM   #3
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help

the fuse box under the dashboard is chevrolet. It was on the truck when it was shipped to thomas.

I would look look for chevrolet C60 wiring diagrams. I dont have one. A factory service manual might be a good purchase.


Post your location... If you are near enough I could stop by for a day or two and help sort out the spaghetti system

william topeka kansas
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Old 07-06-2020, 10:32 AM   #4
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I have found all the wiring diagrams I need for any passenger vehicle (car, light truck) I work on through the public library's online section. They give me access to Chilton's website. Likely you can find info on the Chevy van there, also. Just get a library card, if your local library offers this.
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Old 07-07-2020, 11:32 AM   #5
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Quote:
Originally Posted by JackE View Post
Not a Thomas guy, but I do understand relays. You are exactly wrong the E-C-A relationship. When the relay is in the resting position, power is flowing from E to C. When D is given power, it closes the loop between D and F, which switches the power flow from E to A, rather than E to C.

I'm not even going to begin to guess what any of the relays are for, it could be a dozen different things.

ahhh thank you so much. I was worried I might have. I'm a beginner in the world of electrical terminology and diagrams.
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Old 07-07-2020, 11:59 AM   #6
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Originally Posted by magnakansas View Post
the fuse box under the dashboard is chevrolet. It was on the truck when it was shipped to thomas.

I would look look for chevrolet C60 wiring diagrams. I dont have one. A factory service manual might be a good purchase.


Post your location... If you are near enough I could stop by for a day or two and help sort out the spaghetti system

william topeka kansas

Vermont's a little far from kansas, but thank you! are the c60 and b60 very similar?
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Old 07-07-2020, 12:01 PM   #7
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Originally Posted by Mountain Gnome View Post
I have found all the wiring diagrams I need for any passenger vehicle (car, light truck) I work on through the public library's online section. They give me access to Chilton's website. Likely you can find info on the Chevy van there, also. Just get a library card, if your local library offers this.

Unfortunately I don't currently have a card, and the tiny library in my tiny town is (I believe) still closed. I just checked my roomates account from his old town, but they didn't have the chiltons access. But this seems like it's probably my best bet.
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