Preexisting Wiring Questions

[Rachology]

Hey there, skoolie family! Just as a preface, this is NOT an "I cut X and now my bus won't start" thread. Lol! I just wanna learn some more about my bus's wiring so I can avoid becoming a cautionary tale.

2002 Chevy 6.5L Turbo Diesel Bluebird Microbus

Following the wisdom of several members here, I made sure to label both ends of each wire before removing it, writing down exactly what order I unplugged each wire, then test to make sure the bus starts after unplugging each accessory from the electric panel. So far, it's been working great, I have only unplugged two things that made the bus stop working and was able to immediately identify the problem thanks to that system. 10/10 would recommend to anyone removing wires lol

As for my questions, I mainly just want to make sure I understand what I'm looking at on the things that I can't unplug. Sorry for the wall of text and pictures! Please spare some patience for me if these are silly questions, I'm definitely learning as I go!

1) Vandalock system: The very rear door had a vandalock system wired to the sliding bolt lock and the handle lock. Here's a picture of it before I unplugged it all:

Unplugging everything went fine! Except for that pink wire. I unplugged it from the rear door lock, and traced it back to this relay:

The red* and purple wire go to the start motor relay. I found that unplugging the relay keeps the bus from starting, plugged it back in, bus runs. So, my question is -- am I correct in assuming it's okay to just leave that pink wire? It won't harm the circuit for the starter motor, even if it isn't attached to anything on the other end, right? My understanding based on the schematic I have is that it's just the accessory that would trigger the relay and keep the bus from starting.
Here's a pic of the diagram I have for it, sorry its crummy quality, I can try to upload a better version if need be:


2) master switch solenoid:

That solenoid is attached to the switch on the driver's control panel that used to operate the stop sign and warning lights. The two yellow wires are connected to the switch itself, the pink one is the ground, and the black ones are spliced and connected to a fuse box in the electrical panel, pictured here:

If I unplug that wire, the bus still starts, BUT it hesitates for a moment. Rather than starting to crank immediately, it pauses, then there is a click sound, then it starts to crank. To be safe, I plugged that wire back in but the bus sometimes still hesitates before it cranks. *Edit: it doesn't do this every time I try to crank, though, so I'm wondering now if the pause before cranking is an unrelated issue...*
Sooo..what is that solenoid about? It seems to be what I thought a starter solenoid looks like? But its inside the bus and not on the starter? Why does it affect the ignition? And should I try to remove it or just leave it be? I really want to remove the big black box that the drivers controls are in, but if it's best not to mess with it, I'll live. With the bus still hesitating to start, despite me plugging the culprit back in, I'm pretty nervous about it. Something I noticed too is that the battery light comes on now when I go to crank the bus. Is it possible I have simply drained the battery from all the stopping and starting? Battery guage is still reading right above 14V, which is normal for my bus.

3) Misc.
I also found two wires going to this thing:

The blue and black wires were already cut. Does anyone know what it is? One of the wires leading to it is spliced into a wire already unhooked, the other one goes to this terminal strip, the left prong of what I labeled 2:

Can/should I unplug that? Its counterpart (attached to the adjacent prong), goes under the bus, but I haven't had a chance to track it down.

Thanks so much in advance to anyone who read all of that and can give me some answers! If there is anymore info you need to answer these questions, just let me know! I've already learned so much from this community and I'm excited to learn more.

[RHOMBUS]

Item (1)
Okay, the pink wire that was attached to the rear door isn't attached to the door now, the other end is attached to the relay, and when the relay is left plugged in, everything works just fine? If all of that is true, then you can remove the pink wire completely. If you are going to cut the pink wire instead of removing it, be sure to seal the end so it won't come in contact with anything.

Item (2)
Not really sure there why it still hesitates after plugging back in. Is the other end of the pink wire from above touching any metal?

Item (3)
I had something similar on my Thomas full-size bus and it went to a camera system, with 2 wires going under the bus into the transmission harness so it could overlay the speed onto the video. It was a mess to trace it.

Check the printed labels on the wires. Sometimes that helps identify what the circuit does.

[BlackJohn]

I am having a time getting oriented without seeing the back door switches in place. Pretty sure the pink wire you see at the start relay is the feed for that particular coil. When energized the relay then sends current thru to the starter solenoid and cranking begins if all is well.
Following GMC diagrams is no fun at any time, what you posted as a schematic is blurry making it unreadable to me. Until you know for sure, put the backdoor switches back and keep that circuitry intact. This is a very hard call to make not seing what is happening in that back JB without testing.


John

[BlackJohn]

The pic of your finger pointing at the 20amp fuse, ok to disconnect as it only worked the stop sign and flashing lights. Should in no way imho effect starting. The delay you are noticing could be many things, mostly connection hygiene in the starter system alone. yes, your battery may be getting a bit low on punching power too. Charge them up to eliminate that simple issue before looking further. Should be fine to remove that master switch and contactor and associated wiring totally or leave the power there for future now that you know where the fuse is.


John

[BlackJohn]

Show a pic of the relay with the blue and black wires, get the make. I may have a diagram but have no clue what it did. Sounds disconnected from what you say. Have you tested for power on it?


John

[Rachology]

Originally Posted by RHOMBUS

Item (1)
Okay, the pink wire that was attached to the rear door isn't attached to the door now, the other end is attached to the relay, and when the relay is left plugged in, everything works just fine? If all of that is true, then you can remove the pink wire completely. If you are going to cut the pink wire instead of removing it, be sure to seal the end so it won't come in contact with anything.

Item (2)
Not really sure there why it still hesitates after plugging back in. Is the other end of the pink wire from above touching any metal?

Item (3)
I had something similar on my Thomas full-size bus and it went to a camera system, with 2 wires going under the bus into the transmission harness so it could overlay the speed onto the video. It was a mess to trace it.

Check the printed labels on the wires. Sometimes that helps identify what the circuit does.

1) Yeah, the only thing the pink wire is connected to is the relay at this point. The bus has started normally for a few days with it like that, so I figured it would be fine to just cut and cap it. I just wanted to make double sure!

2) No, it isn't touching any metal currently, and I believe the pink wire is entirely separate from this solenoid thing, too. Pink wire from above went to the vandalock at the rear door. The solenoid is only connected to the master switch for the stop sign and flashers, and that fuse I'm pointing to in the pic. The pink wire doesn't connect with that circuit anywhere.

3) Ooooh, that would make sense! The printed label on the little black box says "A.T.I. 102024". I looked it up but couldn't find anything, unfortunately. The wires are not marked other than their respective numbers that are stamped on the casings. I guess my main question is would it be safe to trace that wire back and remove it from that terminal strip, but leave the other one that goes under the bus alone?

[Rachology]

Originally Posted by BlackJohn

I am having a time getting oriented without seeing the back door switches in place. Pretty sure the pink wire you see at the start relay is the feed for that particular coil. When energized the relay then sends current thru to the starter solenoid and cranking begins if all is well.
Following GMC diagrams is no fun at any time, what you posted as a schematic is blurry making it unreadable to me. Until you know for sure, put the backdoor switches back and keep that circuitry intact. This is a very hard call to make not seing what is happening in that back JB without testing.


John

Hey! Thanks for your help! Sorry I know that pic was not great. Here is the actual pdf file of the schematic! I was having trouble figuring how to upload on mobile.

Rear Vandal Lock(obsolete).pdf

The red and purple wires seem to be the circuit for the starter. I thought it looked like the pink is what energized the coil and opened the circuit of the red and purple, which causes no start?

[Rachology]

Originally Posted by BlackJohn

The pic of your finger pointing at the 20amp fuse, ok to disconnect as it only worked the stop sign and flashing lights. Should in no way imho effect starting. The delay you are noticing could be many things, mostly connection hygiene in the starter system alone. yes, your battery may be getting a bit low on punching power too. Charge them up to eliminate that simple issue before looking further. Should be fine to remove that master switch and contactor and associated wiring totally or leave the power there for future now that you know where the fuse is.


John

Okay, cool! I was hoping the same. It just didn't make any sense to me that that wire would do something to cause starting issues. I guess I just got really hung up over removing that wire because that's the last thing I did before the bus started cranking weird.

[Rachology]

Originally Posted by BlackJohn

Show a pic of the relay with the blue and black wires, get the make. I may have a diagram but have no clue what it did. Sounds disconnected from what you say. Have you tested for power on it?


John

The little relay with the blue and black wires doesn't seem to have any markings on it other than the label that reads "A.T.I. 102024 030327". Here's a closer pic of that label:

I'll inspect it closer when I go out there tomorrow, but that's all I saw on it earlier when I was looking at it. I will also test again for power. It was disconnected by the previous owners, so I don't think it does, but I'll double check to be safe. The only wires that connect to it that weren't snipped by the previous owners are those two white wires. The one stamped 1260, is spliced with other wires, but already disconnected. The other is 1304 and that is what I traced back to that terminal strip.

[Rachology]

So, I think I may have solved the problem with the bus hesitating to start. I think I was hearing the starter solenoid click when I turned the key. I found that when I went back to that solenoid under the driver control panel and retraced the black wires, I was mistaken when I thought they were spliced. They were actually 2 separate wires that went to two separate places in the electrical panel. I just rewired the one that was unhooked, plugged it back in, and the bus starts cranking normally with no pause. I've tried it a couple of times now and there is no issue with the starter cranking each time.

I'm trying to stop myself from obsessively turning over the engine to make sure it starts up normally! Such a relief to hear your bus fire up like a champ after it gives you a scare! Music to my ears!

So I guess that solenoid under the driver controls does have something to do with the starter? Does anyone have any insight on that? I find it weird that the warning system master switch is tied into the bus starting up, but then again, I'm still real new to this. If anyone can share some insight, I would so appreciate it.

Thank you to everyone who has replied and offered help so far! ❤

[BlackJohn]

A couple of things for you...


You misdescribed the problem yesterday in saying the two blacks were spliced. That changes the whole circuitry we are trying to understand.


So, you hooked up the second black anyway. That could be a bad gamble.
You better find out how that solenoid works for the flashers etc. look for its schematic.
You may have set a firehazard up blindly or made a short nit knowing what that second black connected to.

Not sure what its all abut now when the starting circuit is affected by that power. Might be more safties in the circuit for the starter, or who knows.


Your back door handle when closed isn't supplying the starter relay now?


You are loosing me fast.
The pdf you put up is no help. To simplify thaat drawing, leave the JB as is, close the door handle and you should be in start condition. Open handle, no start.


I'm glad you made notes whatever there, marked wires etc, but then screw up tracing and posting a wrong result....I wonder why I bother sometimes.


John